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An overview of the potential use of plants in oral care products

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An Author Correction to this article was published on 29 November 2024, http://doi.org/10.48130/mpb-0024-0030.
  • Problems such as periodontal disease, tooth decay, and oral candidiasis are common conditions that affect people of all ages and geographical zones. They are often associated with poor oral hygiene. Pathogenic microorganisms, their metabolic activity, and inflammation are considered to be the basis of their formation. The search for active substances, components of oral care products, and hygiene products expands this possibility to include research on plant substances with antibacterial, antifungal, and anti-inflammatory properties. Plant extracts such as Rhamus prinoides, Pongamia pinnata, Myrmecodia pendens, Eichhornia crassipes, or the well-known propolis or coffee can effectively reduce the formation of dental plaque and protect against periodontitis. The effect of reducing tooth decay has been demonstrated in relation to extracts from plants such as: Stachytarpheta cayennensis, Mentha spicata, Piper crocatum, Mentha × piperita, Eucalyptus globulus, Clitoria ternatea, Stryphnodendron adstringens, Carum copticum, Phlomis bruguieri, Marrubium parviflorum and Prosopis africana. Rosmarinus officinalis, Punica granatum, Rosa centifolia, Curcuma longa, numerous essential oils (sage, mint, lavender, thyme, hyssop, oregano, lemongrass and others) and other known aromatic plants (including cloves, cinnamon, or Citrus paradisi) had anti-yeast properties. This study aimed to present an up-to-date review of the literature in relation to the latest research and possible potential sources of biologically active plant ingredients for use in preparations, both in prophylaxis and oral hygiene.
  • Bletilla Rchb. f. is one of the most economically valuable groups of orchids in the world. Due to its ornamental significance, the genus Bletilla occupies an important place in the worldwide horticultural market. Furthermore, in China, Japan, South Korea, and other Asian countries, it is highly valued for its medicinal use[1].

    There are eight species in the genus Bletilla, including Bletilla chartacea (King & Pantl.) Tang & F.T. Wang, Bletilla cotoensis Schltr., Bletilla foliosa (King & Pantl.) Tang & F.T. Wang, Bletilla formosana Schltr., Bletilla guizhouensis J. Huang & G.Z. Chen, Bletilla morrisonensis Schltr., Bletilla ochracea Schltr., and Bletilla striata Rchb.f.[2,3]. The distribution area spans from northern Myanmar in Asia to Japan via China[4]. Five species are native to China, namely, B. foliosa, B. formosana, B. guizhouensis, B. ochracea, and B. striata. In China, people have assigned various names to Bletilla based on its morphology and efficacy, such as baiji (白及/白芨), baigen (白根), baige (白给), baijier (白鸡儿), baijiwa (白鸡娃), diluosi (地螺丝), gangen (甘根), junkouyao (皲口药), lianjicao (连及草), and yangjiaoqi (羊角七)[5]. These diverse appellations highlight the importance of this genus in Chinese folk biological culture.

    The medicinal material known as 'baiji' in traditional Chinese medicine (TCM) is usually the dried tuber of B. striata, which is also the authentic product included in the Chinese Pharmacopoeia[6]. According to the Chinese Pharmacopoeia (2020), TCM baiji is sliced, dried, and crushed into a powder that can be used topically or internally, with a recommended dosage of 3–6 g at a time, offering astringent, hemostatic, detumescence, and myogenic effects. It is often used for conditions such as hemoptysis, hematemesis, traumatic bleeding, sores, and skin chaps[7]. Although only B. striata is the authentic product of TCM baiji, the other four Bletilla species native to China are also used as substitutes, and this practice is widespread[8].

    Modern research indicates that Bletilla contains a variety of chemical components, including benzol, dihydrophenanthrene, phenanthrene, and quinone derivatives. These components confer pharmacological effects on Bletilla, such as hemostasis, anti-tumor activity, and promotion of cell growth[9]. Due to its outstanding medicinal value, Bletilla can be found in nearly every corner of the traditional medicine market (Fig. 1). However, habitat destruction and uncontrolled mining have led to a significant reduction in the native populations of Bletilla, making its protection an urgent priority. Therefore, this paper provides a comprehensive review of relevant research up to August 2023, covering botanical characteristics, resource distribution, ethnobotanical uses, chemical components, pharmacological effects, clinical applications, and safety evaluations of Bletilla. The aim is to raise awareness and promote the protection and sustainable use of this genus.

    Figure 1.  Varieties of Bletilla at the traditional March Medicinal Market in Dali, Yunnan, China.

    The morphology of different Bletilla species is highly similar. The primary taxonomic feature distinguishing each species is the characteristics of the flower, particularly the lip of the flower, including its size, shape, and the number and shape of longitudinal ridges on the lip plate (Table 1, Fig. 2)[1014].

    Table 1.  The morphological differences among five species of Bletilla plants native to China.
    Morphological featureBletilla striataBletilla formosanaBletilla ochraceaBletilla foliosaBletilla guizhouensis
    Plant height (cm)18−6015−8025−5515−2045−60
    Rhizome shapeCompressedCompressedSomewhat compressedSubgloboseCompressed
    Rhizome diameter (cm)1−31−2About 21−1.53−4
    Stem characteristicsStoutEnclosed by sheathsStoutStout, shortThin
    Leaf shapeNarrowly oblongLinear-lanceolateOblong-lanceolateElliptic-lanceolateNarrowly lanceolate
    Leaf size (cm)8−29 × 1.5−46−40 × 0.5−4.58−35 × 1.5−2.85−12 × 0.8−325−45 × 1.2−4.5
    Flower colorPurplish red or pinkPale purple or pinkYellowPale purpleDeep purple
    Flower sizeLargeMediumMediumSmall to mediumLarge
    Inflorescence structureBranched or simpleBranched or simpleSimpleSimpleBranched
    Pedicel and ovary length (mm)10−248−12About 187−913−17
    Sepal shapeNarrowly oblongLanceolateLanceolateLinear-lanceolateOblong-elliptic
    Petal shapeSlightly larger than sepalsSlightly narrower than sepalsObliqueLanceolateOblong-elliptic
    Lip shapeObovate-ellipticBroadly ellipticNarrowly rhombic-obovateNarrowly oblongNarrowly oblong
    Lip colorWhite with purplish veinsWhitish to pale yellow with small dark purple spotsWhitish to pale yellow with small dark purple spotsWhite with purplish spots and purple edgeWhite with deep purple edge
    Number of lip Lamellae5 lamellae5 undulate lamellae5 longitudinal lamellae3 fimbriate lamellae7 longitudinal lamellae
    Column characteristicsSubterete, dilated towards apexSubterete, dilated towards apexSlender, dilated towards apexCylindric, dilated towards apexSuberect, with narrow wings
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    Figure 2.  (a)−(d) Bletilla striata (Thunb. ex Murray) Rchb. f. (e)−(h) Bletilla formosana (Hayata) Schltr. (i)−(l) Bletilla ochracea Schltr. (m), (n) Bletilla sinensis (Rolf) Schltr. (o), (p) Bletilla guizhouensis Jie Huang & G.Z. Chen (Photographed by Wang Meina, Zhu Xinxin, and He Songhua).

    The flowers of B. striata are large and purplish-red or pink, with narrowly oblong sepals and petals measuring 25−30 mm in length and 6−8 mm in width. They have acute apices, nearly as long as the sepals and petals. The lip is obovate or elliptic, predominantly white with purplish-red coloration and purple veins, measuring 23−28 mm in length, slightly shorter than the sepals and petals. The lip disc exhibits five longitudinal folds extending from the base to near the apex of the middle lobe, with waviness occurring only above the middle lobe[11]. In China, B. striata is found in regions such as Anhui, Fujian, Guangdong, Guangxi, Gansu, Guizhou, Hubei, Hunan, Jiangsu, Jiangxi, Shaanxi, Sichuan, and Zhejiang. It also occurs in the Korean Peninsula and Japan, thriving in evergreen broad-leaved forests, coniferous forests, roadside grassy areas, or rock crevices, at altitudes ranging from 100−3,200 m[12].

    B. ochracea's flowers are medium to large, featuring yellow or yellow-green exteriors on the sepals and petals, while the insides are yellow-white, occasionally nearly white. The sepals and petals are nearly equal in length, oblong, measuring 18−23 mm long and 5−7 mm wide, with obtuse or slightly pointed apices, often adorned with fine purple spots on the reverse side. The lip is elliptic, typically white or light yellow, measuring 15−20 mm in length and 8−12 mm in width, with three lobes above the middle. The lip disc is characterized by five longitudinally ridged pleats, with undulations primarily occurring above the middle lobe[13]. B. ochracea is native to southeastern Gansu, southern Shaanxi, Henan, Hubei, Hunan, Guangxi, Guizhou, Sichuan, and Yunnan, thriving in evergreen broad-leaved forests, coniferous forests, or beneath shrubs, in grassy areas or alongside ditches at altitudes ranging from 300−2,350 m[14].

    B. formosana's flowers come in shades of lavender or pink, occasionally white, and are relatively small. The sepals and petals are narrowly oblong, measuring 15−21 mm in length and 4−6.5 mm in width, and are nearly equal in size. The sepals have subacute apices, while the petal apices are slightly obtuse. The lip is elliptic, measuring 15−18 mm in length and 8−9 mm in width, with three lobes above the middle. The lip disc exhibits five longitudinal ridge-like pleats, which are wavy from the base to the top of the middle lobe[15]. B. formosana is indigenous to southern Shaanxi, southeastern Gansu, Jiangxi, Taiwan, Guangxi, Sichuan, Guizhou, central to northwest Yunnan, southeast Tibet (Chayu), and Japan. It is typically found in evergreen broad-leaved forests, coniferous forests, road verges, valley grasslands, grassy slopes, and rock crevices, at altitudes ranging from 600−3,100 m[16].

    The flowers of B. foliosa are small and lavender, with white sepals and petals featuring purple apices. The sepals are linear-lanceolate, measuring 11−13 mm in length and 3 mm in width, with subacute apices. The petals are lanceolate, also measuring 11−13 mm in length and 3 mm in width, with acute apices. The lip is white, oblong, adorned with fine spots, and features a purple apex. It measures 11−13 mm in length and 5−6 mm in width, tapering near the base and forming a scaphoid shape. The lip is anteriorly attenuated, unlobed, or abruptly narrowing with inconspicuous three lobes and exhibits fringe-like fine serrations along the edge. Three longitudinal ridge-like pleats are present on the upper lip disc[17]. B. foliosa typically grows on hillside forests, with its type specimen collected from Mengzi City, Honghe Hani and Yi Autonomous Prefecture, Yunnan Province, China[17].

    B. guizhouensis is a recently discovered species in Guizhou, China. In terms of shape, B. guizhouensis closely resembles B. striata, but it can be distinguished by its ovate-oblong buds, oblong dorsal sepals, obovate lips, and middle lobes of the lips, which are oval in shape. The disc of B. guizhouensis features seven distinct longitudinal lamellae, setting it apart from other known Bletilla species and establishing it as a distinct species[2]. Presently, B. guizhouensis has only been found in Guizhou, China, primarily thriving in evergreen broad-leaved forests at altitudes ranging from 900−1,200 m[3].

    Understanding the morphology, habitat, and distribution of Bletilla species is crucial for the conservation and propagation of these resources. To effectively implement plant conservation and breeding programs, a comprehensive understanding of the specific morphological characteristics, growth environments, and native habitats of these plants is essential, as without this knowledge, effective results cannot be achieved.

    The ethnobotanical uses of Bletilla worldwide primarily fall into two categories: ornamental and medicinal purposes. Bletilla orchids, renowned for their striking and distinct flowers, are commonly cultivated for ornamental purposes across many countries[18]. Valued for their aesthetic appeal, these orchids are frequently grown in gardens and utilized as potted plants. Among the various cultivars, B. striata stands out as the most favored choice for ornamental horticulture due to its ease of cultivation and adaptability to diverse climates[19,20].

    Contrastingly, in select Asian countries, Bletilla assumes a crucial role as a medicinal plant. For instance, influenced by TCM, the tuber of Bletilla also serves as a crude drug for hemostatic and anti-swelling purposes in Japan[21]. Likewise, traditional Korean medicine, deeply rooted in TCM principles, extensively documents the versatile use of Bletilla in addressing issues such as alimentary canal mucosal damage, ulcers, bleeding, bruises, and burns[22]. In Vietnam, Bletilla has been used as a medicinal herb for treating tumors and skin fissures, aligning with practices observed in the ethnic communities of southwest China[23].

    In China, Bletilla boasts a longstanding medicinal history, with numerous classical ancient Chinese medicine books containing detailed records of its medicinal applications[2432]. Even in contemporary society, many ethnic groups residing in mountainous areas in China continue to uphold the traditional medical practice of using Bletilla medicinally[31].

    In ancient Chinese medical literature, detailed records of Bletilla's morphology can be traced back to the late Han Dynasty, around 200 AD[24]. The Mingyi Bielu, a historical source, documented, 'Bletilla grows in the valley, with leaves resembling those of Veratrum nigrum L., and its root is white and interconnected. The ideal time for harvesting is September'. As awareness of the medicinal significance of Bletilla grew, successive dynastic-era Chinese medical texts consistently included descriptions of Bletilla's morphology (Table 2). In the Ming Dynasty, Li Shizhen compiled these earlier accounts of Bletilla's plant characteristics in his work, the Compendium of Materia Medica. He even provided an illustrative depiction of this plant genus (Fig. 3)[25].

    Table 2.  Morphological description of the plants belonging to Bletilla in the ancientChinese medicinal books.
    Dynasty (Year)TitleAuthorOriginal ChineseEnglish translation
    Late Han
    (184−220 AD)
    Mingyi Bielu/白给生山谷, 叶如藜芦,
    根白相连, 九月采
    Bletilla grows in the valley, with leaves like Veratrum nigrum L., root is white and connected. September is the time for harvesting.
    Wei-Jin period
    (220−420 AD)
    WuPu BencaoWu Pu白根, 茎叶如生姜, 藜芦,
    十月花, 直上, 紫赤色,
    根白连, 二月, 八月, 九月采
    Bletilla, stems and leaves like Zingiber officinale Roscoe and V. nigrum. It blooms in October and is purple and red, the inflorescence is vertical and upward. The roots are white and connected. It can be dug in February, August, and September.
    the Northern and Southern
    (420−589 AD)
    Bencao JizhuTao Hongjing近道处处有之, 叶似杜若,
    根形似菱米, 节间有毛
    It is everywhere near the road. The leaves are like Pollia japonica Thunb. The roots are like the fruit of Trapa natans L., and internode are many fibrous roots.
    Tang
    (618−907 AD)
    Su Jing, Zhangsun Wuji, etcTang materia medica生山谷, 如藜芦, 根白连, 九月采Born in the valley, with leaves like V. nigrum, root is white and connected. September is the time for harvesting.
    Song
    (960−1279 AD)
    Su SongCommentaries on the Illustrations白芨, 生石山上。春生苗,
    长一尺许, 似栟榈及藜芦,
    茎端生一台, 叶两指大, 青色,
    夏开花紫, 七月结实, 至熟黄黑色。
    至冬叶凋。根似菱米, 有三角白色, 角端生芽。二月, 七月采根
    Bletilla grow on the stone hill. It sprouts in spring and grows about a foot long. The seedlings are like Trachycarpus fortunei (Hook.) H. Wendl. and V. nigrum. The leaves are two finger-size. In summer, it blooms purple flowers and bears fruit in July. The ripe fruit is yellow-black. The leaves wither in winter. The root is like the fruit of T. natans, with three corners, white, and sprouting at the corners. The roots are dug in February and July.
    Ming
    (1368−1644 AD)
    Li ShizhenCompendium of Materia Medica一棵只抽一茎, 开花长寸许,
    红紫色, 中心如舌, 其根如菱米,
    有脐, 如凫茈之脐,
    又如扁扁螺旋纹, 性难干
    Only one stem per herb. The flower is more than one inch long, red and purple, and the center resembles a tongue. Its root is similar to the fruit of T. natans, possessing an umbilicus akin to that of Eleocharis dulcis (N. L. Burman) Trinius ex Henschel. It has spiral veins and is challenging to dry.
    −, Anonymous.
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    Figure 3.  Bletilla in Compendium of Materia Medica.

    Generally, ancient Chinese medical texts did not make clear distinctions between different Bletilla species. They collectively referred to plants with similar morphological traits as 'baige', 'baigen', 'baiji', 'gangen', 'lianjicao', or 'ruolan'. However, through textual analysis, it has been established that the descriptions of Bletilla in ancient texts before the Ming Dynasty largely align with Bletilla striata in terms of plant height, pseudo-bulb shape, leaf morphology, flower and fruit colors, and other characteristics. While the Bletilla portrayed in attached images may not precisely match B. striata in terms of morphology, considering the textual descriptions, it generally corresponds with B. striata. In writings from the Ming Dynasty and later periods, more specific descriptions of Bletilla emerged, encompassing details about its vascular arrangement, inflorescence, and flower structure, which consistently align with B. striata. Consequently, researchers have corroborated that the original plant of Bletilla described in ancient texts is Bletilla striata[24,33].

    According to the ancient Chinese medicinal books, Bletilla was used to treat a wide variety of conditions, including coughing, bruising, and bleeding, but their most mentioned use in ancient Chinese texts is for skin whitening and freckle removal[25]. Since ancient times, Bletilla species have been used consistently for skin care and whitening, and there are many well-known skincare products related to Bletilla. These Chinese formulae with Bletilla are similar to modern facial masks, face creams, facial cleanser, hand creams and other skin care products[26].

    For example, a prescription for 'facial fat (面脂)' in Medical Secrets from the Royal Library (752 AD) is made by boiling Bletilla with other traditional ingredients, and is applied to the face, resulting in skin whitening, freckle and wrinkle removal[27]. The 'Angelica dahurica cream (白芷膏)' in the General Medical Collection of Royal Benevolence (1111−1125 AD) is reputed to whiten facial skin through a seven-day treatment regiment, and contains Bletilla as the main botanical ingredient along with Angelica dahurica[28]. Jingyue Quanshu (1563-1640 AD) also contains a prescription called 'Yurong powder (玉容散)' for facial skin care. 'Yurong powder' is made of a fine powder of Bletilla, Nardostachys jatamansi (D. Don) DC., Anthoxanthum nitens (Weber) Y. Schouten & Veldkamp and other herbs[29]. Washing the face with Yurong powder in the morning and evening every day is said to make a person's face white without blemishes (Fig. 4)[29].

    Figure 4.  Yurong powder made of Bletilla and other traditional Chinese medicines in Jingyue Quanshu.

    In addition, in ancient Chinese medicine texts, Bletilla is also a well-known medicine for treating hematemesis, hemoptysis and bruises[23]. According to Shennong's Classic of Materia Medica (25−220), grinding the white fungus into fine powder and taking it after mixing with rice soup can be effective for treating lung damage and hematemesis[30]. Among the Prescriptions for Universal Relief (1406), 18 traditional Chinese medicines, such as Bletilla, are used to make 'snake with raw meat cream', which is said to be useful to treat carbuncles and incised wounds[31]. There is also a record of Bletilla powder treating lung heat and hematemesis in the Collected Statements on the Herbal Foundation (1624)[32].

    In ancient Chinese medicinal texts, most Bletilla are said to be useful for lung injury and hemoptysis, epistaxis, metal-inflicted wounds, carbuncles, burns, chapped hands and feet, whitening and especially for skin care. In the ancient medicinal texts, Bletilla is used alone or mixed with other traditional Chinese medicines. It is usually used in the form of a powder. The various medicinal effects of Bletilla described in these ancient texts suggest the great potential of this genus in clinical application, especially in the market of skin care products and cosmetics.

    As a skin care herb praised by ancient medical classics, 11 ethnic minorities in China, such as Bai, Dai, De'ang, Jingpo, Lisu, Miao, Mongolian, Mulao, Tu, Wa, and Yi still retain the traditional habit of using Bletilla for skin care in their daily life (Table 3). In addition to B. striata, B. formosana and B. ochracea are also used as substitutes. Although Chinese ethnic groups have different names for Bletilla spp., the skin care methods are basically the same. Dry Bletilla tubers are ground into a powder and applied to the skin[34], and this usage is also confirmed by the records in ancient medical texts[23, 24]. The various local names of Bletilla by different ethnic groups also indirectly suggests which ethnic groups play an important role in the traditional use. For example, Bai people called B. striata baijier (白鸡儿), goubaiyou (狗白尤), and yangjiaoqi (羊角七) (Table 3).

    Table 3.  The traditional medicinal knowledge of Bletilla in ethnic communities, China.
    Ethnic groupLatin nameLocal nameUsed partUse methodMedicinal effect
    AchangBletilla striata (Thunb. ex Murray) Rchb. F.BaijiTuberAfter the roots are dried, chew them orally or grind them into powder for external applicationTuberculosis, hemoptysis, bleeding from gastric ulcer, burns and scalds
    BaiBaijier, Goubaiyou, YangjiaoqiTuberTreatment of tuberculosis hemoptysis, bronchiectasis hemoptysis, gastric ulcer hemoptysis, hematochezia, skin cracking
    DaiYahejieTuberUsed for tuberculosis, tracheitis, traumatic injury, and detumescence
    De'angBageraoTuberTuberculosis, hemoptysis, bleeding from gastric ulcer, burns and scalds
    DongShaque, SanjueTuberTreat hematemesis and hemoptysis
    JingpoLahoiban, PusehzuotuberFor tuberculosis, bronchiectasis, hemoptysis, gastric ulcer, hematemesis, hematuria, hematochezia, traumatic bleeding, burns, impotence
    MengMoheeryichagan, NixingTuberFor tuberculosis hemoptysis, ulcer bleeding, traumatic bleeding, chapped hands, and feet
    MiaoBigou, Wujiu, SigouTuberUsed for hemoptysis of tuberculosis, bleeding of ulcer disease, traumatic bleeding, chapped hands, and feet
    MolaoDajiebaTuberTreat internal and external injuries caused by falls
    TibetanSanchabaijiTuberFresh chopped and soaked with honey; Powdered after sun-dried, then taken with honey and waterMainly used to treat cough, asthma, bronchitis, lung disease and a few gynecological diseases
    TuRuokeyeTuberAfter the roots are dried, chew them orally or grind them into powder for external applicationTreatment of tuberculosis, hemoptysis, bloody stool, chapped skin
    WaBaijiTuberAfter the roots are dried, chew them orally or grind them into powder for external applicationFor tuberculosis, hemoptysis, gastrointestinal bleeding, scald and burn
    YaoBiegeidaiTuberTreat gastric ulcer, pulmonary tuberculosis, cough, hemoptysis, and hematemesis
    YiDaibaij, Tanimobbaili, Niesunuoqi, AtuluoboTuberTreatment of tuberculosis, hemoptysis, golden wound bleeding, burns, chapped hands and feet
    ZhuangManggounuTuberTreat stomachache and hemoptysis
    BaiBletilla formosana (Hayata) Schltr.Baijier, YangjiaoqiTuberAfter the roots are dried, chew them orally or grind them into powder for external applicationIt is used for emesis, hemoptysis due to tuberculosis, and hemoptysis due to gastric ulcer. External application for treatment of incised wound
    MiaoLianwuTuberThe effect is the same as that of B. striata
    LisuHaibiqiuTuberIt can treat tuberculosis, hemoptysis, epistaxis, golden sore bleeding, carbuncle and swelling poison, scald by soup fire, chapped hands and feet
    YiNiesunuoqi, Yeruomaoranruo, Atuluobo, Ribumama, Atuxixi, Abaheiji, Binyue, ZiyouTuberIt is used for tuberculosis, hemoptysis, traumatic injury, treatment of frostbite, burn, scald, bed-wetting of children and other diseases
    BaiBletilla ochracea Schltr.Baijier, YangjiaoqiTuberAfter the roots are dried, chew them orally or grind them into powder for external applicationFor hematemesis, epistaxis, hemoptysis due to tuberculosis, hemoptysis due to gastric ulcer; External application of golden sore and carbuncle
    MengMoheeryichagan, NixingtuberThe effect is the same as that of B. striata
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    The formation of traditional medical knowledge among Chinese people is often directly related to the specific living environment and cultural background[34]. For example, the Bai, Dai, De'ang, Jingpo, Lisu Yi, Wa and other ethnic minorities live in mountainous areas. The cold weather in winter and year-round outdoor manual work makes it difficult to maintain their skin[35, 36]. In the face of this situation, the ethnic people who are concerned about their physical appearance have long ago chosen local Bletilla species for skin care, and have handed down this tradition for many generations[34]. This important traditional skin care tradition is worthy of further in-depth study.

    The six main classes of Bletilla chemical components, phenanthrene derivatives, phenolic acids, bibenzyls, flavonoids, triterpenoids, and steroids, have been described previously. Almost three hundred compounds have been isolated from Bletilla, including 116 phenanthrene derivatives, 58 phenolic acids, 70 bibenzyls, 8 flavonoids, 24 triterpenoids and steroid and 13 other compounds (Figs 514). Chemical structures of the isolates of Bletilla species most are phenanthrene derivatives, which have been demonstrated to possess various pharmacological activities.

    The prominent opioids oxycodone, hydrocodone, naloxone, and naltrexone are all phenanthrene derivatives[37]. Currently, phenanthrene derivatives (Fig. 5, 1 to 66) were isolated from B. formosana, B. ochracea, and B. striata. In 2022, 17 phenanthrene derivatives (117) were isolated from the ethyl acetate (EtOAc) extracts of B. striata tubers[38]. Then, other phenanthrene derivatives were isolated from Bletilla, such as dihydrophenanthrenes (1841), phenanthrenes (4266), biphenanthrenes (Fig. 6, 6789), dihydro/phenanthrenes with uniquestructures (90112) and phenanthraquinones (Fig. 7, 113116). Thus far, this genus has been documented to include these compounds, which have been shown to exhibit pharmacological actions[3945].

    Figure 5.  Phenanthrene derivatives from Bletilla species (1−66)[3841,4345,47,49,58,7072,7479].
    Figure 6.  Phenanthrene derivatives from Bletilla species (67−105)[41,43,49,5961,70,76,7986].
    Figure 7.  Phenanthrene derivatives from Bletilla species (106−116)[43,49,70,75,84,85,87].

    Phenolic acids are carboxylic acids created from the skeletons of either benzoic or cinnamic acids[4648]. Fifty-eight phenolic acids (Figs 810, 117 to 174) were isolated from B. formosana, B. ochracea, and B. striata.

    Figure 8.  Phenolic acids from Bletilla species (117−134)[1,5,36,4752,54,67,88,90].
    Figure 9.  Phenolic acids from Bletilla species (135−169)[39,45,4854,56,61,68,69,73,76,82,83,8994].
    Figure 10.  Phenolic acids from Bletilla species (170−174)[20,95].

    For example, compounds 121, 126, 139, 141, 148, 149, 154, 155 and 157 were isolated from the rhizomes of B. formosana[1,49,5052]. The structures of these compounds were determined, mostly from their NMR spectroscopy data. Additionally, protocatechuic (136) and vanillin (137) also have been isolated from B. striata[53]. Moreover, some bioactive components such as 2-hydroxysuccinic acid (164) and palmitic acid (165) have been discovered and identified from B. striata[20,5456].

    The bibenzyls were small-molecular substances with a wide range of sources, which were steroidal ethane derivatives and resembling the structural moiety of bioactive iso-quinoline alkaloids[57].

    For example, depending on their structural characteristics, 70 bibenzyl compounds (Fig. 11, 175 to 244) can be grouped into three groups, simple bibenzyls (175186, 233238), complex bibenzyls (189225) and chiral bibenzyls (226-232, 239-244)[5860].

    Figure 11.  Bibenzyls from Bletilla species (175-244)[1,4042,47,49,50,5860,70,73,76,9699].

    Flavonoids are among the most common plant pigments. Eight bibenzyls (Fig. 12, 245 to 252) have been isolated from B. formosana, B. ochracea, and B. striata. Apigenin (245) and 8-C-p-hydoxybenzylkaempferol (249) were isolated from the whole plant of B. formosana[45]. Bletillanol A (250), bletillanol B (251) and tupichinol A (252) were isolated from B. striata[61]. The names and chemical structures of the flavonoids reported from Bletilla are shown below (Fig. 12).

    Figure 12.  Flavonoids from Bletilla species (245–252)[45,61].

    Twenty-four triterpenoids and steroids (Fig. 13, 253 to 276) have been reported from Bletilla (Fig. 13), such as, tetracyclic triterpenes (253259) and pentacyclic triterpenes (189225) and chiral bibenzyls (260)[6264]. Steroids (261276) isolated from the Bletilla and have shown some bioactivity. For example, bletilnoside A (272) was isolated from Bletilla species and displayed anti-tumor activity[65,66].

    Figure 13.  Triterpenoids and steroid compounds from Bletilla species (253-276)[56,6265].

    Thirteen other compounds (Fig. 14, 277 to 289) were isolated from B. formosana, B. ochracea, and B. striata. These compounds included amino acids, indoles and anthraquinones[67,68]. For example, syringaresinol (285) and pinoresinol (286) have been described in the methanol extract of the tubers of B. striata[61].

    Figure 14.  Others compounds from Bletilla species (277−289)[50,54,61,62,67,68,94,97].

    Based on the information about the chemical constituents of Bletilla species, it appears that there is a substantial body of research on these compounds. However, there are some areas that may warrant further investigation and research. At first, it would be valuable to investigate potential synergistic effects and interactions between the different classes of compounds within Bletilla species, as some of the compounds may work together. Besides, it is worth considering the improvement of compound yield. Optimizing extraction methods and finding the most efficient and environmentally friendly techniques are vital for both research purposes and potential commercial applications. It is also important to take into account the variability in chemical composition among different Bletilla species and even within the same species from different cultivars.

    The rich and varied chemical components make the plants of Bletilla have a wide variety of pharmacological activities (Table 4). Many studies have shown that the plants of this genus have anti-inflammatory, antineoplastic, antiviral, antioxidant, hemostatic, antibacterial, and other biological activities, which help to support the traditional medicinal practice of Bletilla in folk medicine.

    Table 4.  Summary of the pharmacological activities of Bletilla species.
    Pharmacological activityTested substance/partTested system/organ/cellTested dose/dosing methodResultsRefs.
    Anti-inflammatoryEthanol extract of Bletilla striataRAW264.7 cells RAW264.7 cells were pre-treated with ethanol extract of B. striata for 1 h and then stimulated with LPS (200 ng/mL) for 12 h, 0.05% DMSO was applied as the parallel solvent control. The culture supernatant was collected for IL-6 and TNF-α detection.Ethanol extract of B striata significantly inhibited LPS-induced interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) expression at 2.5 µg/mL.[41]
    The ethyl acetate-soluble (EtOAc) extract of tubers of B. striataH2O2-induced PC12 cell injury modelPC12 cells were seeded in 96-well multiplates at a density of 1.5 × 105 cells/mL. After overnight incubation at 37 °C with 5% CO2, 10 μM test samples and H2O2 (final concentration of 450 μM) were added into the wells and incubated for another 12 h.It protected the cells with the cell viabilities of 57.86 ± 2.08%, 64.82 ± 2.84%, and
    64.11 ± 2.52%.
    [98]
    Ethanol extract of tubers of B. striataRAW264.7 cellsCells were treated with ethanol extracts (25 μM) dissolved in DMSO, in the presence of
    1 μg/mL lipopolysacchride
    (LPS) for 18 h
    The anti-inflammatory activity with IC50 of 2.86 ± 0.17 μM.[54]
    PE extract of the tubers of B. striataLPS-stimulated BV2 cellsCells treated with extract
    (0, 1, 10, 30, 100 μg/mL) and dihydropinosylvi (0, 1, 10, 30, 100 μM) in presence of LPS
    (1 μg/mL)
    The anti-inflammatory activity with IC50 values of 96.0 μM.[96]
    Ethanol extract of the roots of B. striataCox-1 and Cox-2Treated with the ethanol extracts at various concentrations
    (0, 1, 10, 100 μM)
    The compounds with sugar moieties displayed selective inhibition of Cox-2 (N90%).[38]
    B. striata polysaccharide (BSPb)Human mesangial cells (HMCs)HMCs were pre-treated with BSPb (5, 10, 20 μg/mL)BSPb efficiently mediated expression of NOX4 and TLR2, to attenuate generation of ROS and inflammatory cytokines.[12]
    Compounds extracted from the rhizomes of Bletilla ochraceaRAW264.7 cellsAfter 24 h preincubation,
    cells were treated with serial dilutions in the presence of
    1 μg/mL LPS for 18 h. Each compound was dissolved in DMSO and further diluted in medium to produce different concentrations. NO production in the supernatant was assessed by adding 100 μL of Griess regents.
    It showed the inhibitory effects with IC50 values in the range of 15.29–24.02 μM.[76]
    Compounds extracted from the rhizomes of B. ochraceaMurine monocytic RAW264.7 cellsAfter 24 h preinubation, RAW 264.7 cells were treated with compounds (25 μM) dissolved in DMSO, in the prenence of
    1 μg/mL LPS for 18 h. NO production in each well was assessed by adding 100 μL of Giress regent
    It showed the inhibitory effects with IC50 2.86 ± 0.17 μM.[86]
    Compounds extracted from the rhizomes of Bletilla formosanaElastase Release AssaysNeutrophils (6 × 105 cells/mL) were equilibrated in MeO-Suc-Ala-Ala-Pro-Val-p-nitroanilide (100 μM) at 37 °C for 2 min and then incubated with a test compound or an equal volume of vehicle (0.1% DMSO, negative control) for 5 min.Most of the isolated compounds were evaluated for their anti-inflammatory activities. The results showed that IC50 values for the inhibition of superoxide anion generation and elastase release ranged from 0.2 to 6.5 μM and 0.3 to 5.7 μM, respectively.[49]
    Anti-tumorTwo compounds from Bletilla striataA549 cellsCompounds were tested for their ability to induce ROS generation in A549 cells at concentrations of 20 two compounds for 24 h, the cells were harvested to evaluate the ROS production.The two compounds exhibited antiproliferative effects using the MTT test; these effects may be due to cell cycle arrest and inducing ROS generation.[87]
    Stilbenoids from B. striataBCRP-transduced K562 (K562/BCRP) cellsIt showed antimitotic activity and inhibited the polymerization of tubulin at IC50 10 μM.[78]
    Compounds extracted from the rhizomes of B. ochraceaThe human tumor cell lines HL-60 (acute leukemia), SMMC-7721 (hepatic cancer), A-549 (lung cancer), MCF-7 (breast cancer), and SW480 (colon cancer)100 μL of adherent cells were seeded into each well of 96-well cell culture plates. After 12 h of incubation at 37 °C, the test compound was added. After incubated for 48 h, cells were subjected to the MTS assay.All isolated metabolites except 7 were evaluated for cytotoxic activity against five human cancer cell lines (HL-60, SMMC7721, A-549, MCF-7 and SW480).[76]
    AntiviralThe tuber of B. striataMadin-Darby canine kidney model and embryonated eggs modelAs simultaneous treatment with 50% inhibition concentration (IC50) ranging from 14.6 ± 2.4 to 43.3 ± 5.3 μM.Phenanthrenes from B. striata had strong anti-influenza viral activity in both embryonated eggs and MDCK models.[107]
    The 95% ethanol
    Extract of B. striata
    BALB/C miceIt has significant anti-influenza
    virus effect in mice, which may be related to the increase of IL-2, INFα, INF-β and thus enhance the immune function of mice.
    [12]
    AntioxidantCompounds extracted from the rhizomes of B. formosanaDPPH radical-scavenging assaySolutions containing 160 μL of various concentrations of sample extract, 160 μL of various concentrations of BHA, 160 μL of various concentrations of ascorbic acid, and the control (160 μL of 75% methanol) were mixed separately with 40 μL of 0.8 mM DPPH dissolved in 75% methanol. Each mixture was shaken vigorously and left to stand for 30 min at room temperature in the dark.Tthe seedlings grown by tissue culture of B. formosan collected in Yilan County had the best antioxidant capacity. In addition, B. formosana collected in Taitung County had the best scavenging capacity in the tubers, leaves and roots.[93]
    Fibrous roots of B. striataDPPH model and superoxide anion systemThe ABTS+ solution was prepared by reacting 7 Mm ABTS with 2.45 mM potassium persulfate (final concentrations both dissolved in phosphate buffer, 0.2 M, pH 7.4) at room temperature for 12–16 h in the dark.It removed free radicals and inhibit tyrosinase activity.[33]
    B. striata extracts (BM60)The murine macrophage cells NR8383, male SD mice (180~200 g)NR8383 were pretreated with extracts (1, 10 and 100 g/mL) for 4 h and then 65 stimulated with 1 g/mL of LPS for 24 h. Acute lung injury was induced in mice by nonhexposure intratracheal instillation of LPS (3.0 mg/kg). Administration of the BM60 extract of 35, 70, and 140 mg/kg (L, M, H) was performed by oral gavages.The BM60 treatment reduced the production of NO in NR8383 macrophages. Treatments with BM60 at the doses of 35, 70, 140 mg/kg significantly reduced macrophages and
    neutrophils in the bronchoalveolar lavage fluid (BALF).
    [12]
    The crude
    polysaccharides obtained from B. striata
    DPPH free radical scavenging activityConcentration
    range of 2.5–5.0 mg/mL
    The IC50 of BSPs-H was 6.532 mg/mL.[35]
    HemostasisB. striata polysaccharide (BSP)Diabetes mellitus (DM) mouse models were induced by high fat-diet feeding combined with low-dose streptozocin injectionDM mouse models were induced by high fat-diet feeding combined with low-dose streptozocin injection. The BSP solutions were applied on the surface of each wound at a volume of 50 μl. RD mice were assigned as normal controls and received saline treatment (n = 6). All mice were treated with vehicle or BSP once daily from the day of wounding (d0) until 12 days later (d12).BSP administration accelerated diabetic wound healing, suppressed macrophage infiltration, promoted angiogenesis, suppressed NLRP3 inflammasome activation, decreased IL-1β secretion, and improved insulin sensitivity in wound tissues in DM mice.[112]
    B. striata Micron Particles (BSMPs)Tail amputation model and healthy male Sprague-Dawley (SD) rats
    (250 ± 20 g, 7 weeks of
    age)
    Rats were divided into six groups of five treated with cotton gauze and BSMPs (350–250, 250–180, 180–125, 125–75, and < 75 μm), respectively.Compared to other BSMPs of different size ranges, BSMPs of 350–250 μm are most efficient in hemostasis. As powder sizes decrease, the degree of aggregation between particles and hemostatic BSMP effects declines.[109]
    Rhizoma Bletillae polysaccharide (RBp)Adult male SD rats weighing 220 ± 20 gAfter incubation for 1 min at 37 °C, 300 μL of PRP was dealt with different concentrations of RBp (50, 100, 150, and 200 mg/L) under continuous stirring, and the vehicle was used as the blank control.RBp significantly enhanced the platelet aggregations at concentrations of 50−200 mg/L in a concentration-dependent manner.[113]
    AntibacterialBibenzyl derivatives from the tubers of Bletilla striataS. aureus ATCC 43300, Bacillus subtilis ATCC 6051, S. aureus ATCC 6538 and Escherichia coli ATCC 11775Using a microbroth dilution method, bacteria were seeded at
    1 × 106 cells per well (200 μL) in a
    96-well plate containing Mueller-Hinton broth with different concentrations (from 1 to 420 μg/mL, 300 μg/mL and so on;
    2-fold increments) of each test compound.
    It showed inhibitory activities with MIC of (3–28 μg/mL) against S. aureus ATCC6538[116]
    The crude extract of B. striataS. album, A. capillaris, C. cassiaThey were seeded at 1 × 106 cells per well (200 μL) in a 96-well plate containing Mueller−Hinton broth (meat extracts 0.2%, acid digest of casein 1.75%, starch 0.15%) with different concentrations (from 1 to 128 μg/mL; 2-fold increments) of each test compound.It showed S. album (0.10%), A. capillaris (0.10%), and C. cassia (0.10%) to have the strongest antibacterial properties.[118]
    The ethyl acetate-soluble (EtOAc) extract of tubers of B. striataS. aureus ATCC 43300, S. aureus ATCC 6538, and Bacillus subtilis ATCC 6051) and Escherichia coli ATCC 11775)Bacteria were seeded at 1 × 106 cells per well (200 μL) in a 96-well plate containing Mueller Hinton broth with different concentrations (from 1 to 420 μg/ml; 2-fold increments) of each test compound.The extract was effective against three Gram-positive bacteria with minimum inhibitory concentrations (MICs) of 52–105 μg/ml.[98]
    The phenanthrene fraction (EF60) from the ethanol extract of fibrous roots of Bletilla striata pseudobulbsS. aureus ATCC 25923, S. aureus ATCC 29213, S. aureus ATCC 43300, E. coli ATCC 35218, and P. aeruginosa ATCC 27853, Bacillus subtilis 168EF60 was active against all tested strains of Staphylococcus aureus, including clinical isolates and methicillin-resistant S. aureus (MRSA). The minimum inhibitory concentration (MIC) values of EF60 against these pathogens ranged from 8 to 64 μg/mL.EF60 could completely kill S. aureus ATCC 29213 at 2× the MIC within 3 h but could kill less than two logarithmic units of ATCC 43300, even at 4× the MIC within 24 h. The postantibiotic effects (PAE) of EF60 (4× MIC) against strains 29213 and 43300 were 2.0 and 0.38 h, respectively.[117]
    Anti-adhesiveBletilla striata extraction solutionPPA was induced by cecal wall abrasion, and Bletilla striata was injected to observe its efect on adhesion in ratsThe rats in the sham operation group was not treated; the other rats of the three experimental groups were intraperitoneally injected with 8 ml of phosphate-buffered saline (Control group), 15% Bletilla striata extraction solution (BS group), and 0.2% hyaluronic acid solution (HA group), respectively.Bletilla striata decreased the development of abdominal adhesion in abrasion-induced model of rats and reduced the expression of the important substance which increased in PPAs.[120]
    ImmunomodulatoryB. striata polysaccharide (BSPF2)Mouse spleen cellsTo observe the immune activity of BSPF2, mouse spleen cells were stimulated with BSPF2 at 10–100 g/mL for 72 h.Immunological assay results demonstrated that BSPF2 significantly induced the spleen cell proliferation in a dose-dependent manner.[121]
    Anti-pulmonary fibrosisB. striata polysaccharideClean grade male SD ratsSD rats were randomly divided into 5 groups, sham operation group (equal volume of normal saline), model group (equal volume of normal saline), tetrandrine positive control (24 mg/kg) group and white and Polysaccharide low
    (100 mg/kg) and high (400 mg/kg) dose groups.
    The Bletilla striata polysaccharide has remarkable regulation effect on anti-oxidation system and immune system, but cannot effectively prevent lung fibrosis.[127]
    Small molecule components of Bletilla striataClean grade male SD ratsSD rats were randomly divided into 5 groups, sham operation group (0.5 mL normal saline), model group (0.5 mL normal saline), and positive control group (tetrandrine 24 mg/kg) and low (20 mg/kg) and high (40 mg/kg) dosage groups of the small molecule pharmacological components of Bletilla, which were administered by gavage once a day for 2 consecutive months.The small molecule components of Bletilla striata can effectively prevent lung fibrosis though regulating the anti-oxidation system,immune system and cytokine level; SMCBS is one of the active components of Bletilla striata on silicosis therapy[124]
    —, not given.
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    Many phytochemicals have been well characterized to lessen swelling or inflammation[89]. A series of phenolic acid and polysaccharide compounds isolated from Bletilla demonstrated anti-inflammatory bioactivity against BV-2 microglial, RAW 264.7, and PC12 cells[96,100102]. For example, phochinenin K (106) exhibited growth inhibitory effects with an IC50 of 1.9 μM, and it is a possible candidate for development as neuroinflammation inhibitory agent[43]. Using the H2O2-induced PC12 cell injury model, (7S)-bletstrin E (242), (7R)-bletstrin F (243) and (7S)-bletstrin F (244) could clearly protect the cells with the cell viabilities of 57.86% ± 2.08%, 64.82% ± 2.84%, and 64.11% ± 2.52%, respectively[98]. With an IC50 of 2.86 ± 0.17 μM, 2,7-dihydroxy-4-methoxyphenanthrene (53) showed potential action against NO generation in RAW 264.7 macrophages[54]. The use of Bletilla in traditional skin care, it is said to function as an astringent, hemostatic and wound healing[33]. Modern medical pharmacology research has validated that this plant has antibacterial effects, which may may help to explain, in part, its traditional use in skin care[24].

    Though it's mentioned that some of these compounds from Bletilla have demonstrated anti-inflammatory action, more extensive studies are needed to fully understand their mechanisms of action, potential therapeutic applications, and safety profiles. Conducting in vivo studies and clinical trials can provide more concrete evidence of their effectiveness.

    There are important antineoplastic agents that have originated from plant natural products[103]. In recent years, several bibenzyl and flavonoid compounds have been discovered from Bletilla that have antineoplastic activity against A549 cells and other cells. For example, 7-hydroxy-2-methoxy-phenanthrene-3,4-dione (160) and 3′,7′,7-trihydroxy-2,2′,4′-trimethoxy-[1,8′-biphenanthrene]-3,4-dione (163) have shown strong antiproliferative effects and induced ROS production after 24 h in A549 cells[87]. The doxorubicin (Dox)/FA (folate)-BSP-SA (stearic acid) modified Bletilla striata polysaccharide micelles boosted the drug enrichment in tumors and improved the in vivo anticancer effects[104,105]. Micelles, nanoparticles, microspheres, and microneedles are examples of B. striata polysaccharide-based drug delivery systems that exhibit both drug delivery and anti-cancer functionality. These experiments confirmed that some of the compounds isolated from the Bletilla have potential activity for the treatment of cancer.

    However, most of the evidence presented in the previous studies is based on in vitro experiments or cell culture studies. It is highly necessary to use animal models to study the in vivo anti-tumor effects of Bletilla extracts or compounds. These studies can help evaluate the safety and effectiveness of treatments based on Bletilla. Additionally, through such methods, researchers can further investigate the mechanisms of Bletilla's anti-tumor activities, exploring how Bletilla compounds interact with cancer cells, immune responses, and signaling pathways involved in tumor growth and metastasis.

    Antiviral medications are essential for preventing the spread of illness, and are especially important nowadays with pandemics and drug-resistant viral strains[5, 6]. Therefore, it is vitally necessary to find novel, safe, and effective antiviral medications to treat or prevent viral infections[106]. B. striata plant contains compounds that have been recorded in ancient texts to cure cough, pneumonia, and skin rashes, and these may be related to potential antiviral constituents[23]. Some constituents of B. striata have antiviral activity, for example, phenanthrenes and diphenanthrenes from B. striata displayed potent anti-influenza viral in a Madin-Darby canine kidney model and embryonated eggs model, diphenanthrenes with parentally higher inhibitory activity than monophenanthrenes[107]. But more research is needed to further determine the antiviral activity of Bletilla, understand how Bletilla compounds interact with viral proteins or the host immune response, and conduct safety and toxicity studies, which are crucial for the development of related materials.

    Free radicals have the potential to exacerbate lipid peroxidation and harm cell membranes, which can lead to several prevalent human diseases, including cancer, cataracts, and coronary heart disease[108]. Research has shown that extracts from Bletilla possess strong antioxidant activity. However, this antioxidant activity can vary depending on the different growing environments of the plant. Additionally, the antioxidant capabilities of extracts from different parts of the Bletilla plant also vary[93]. Clinical studies have shown that traditional Chinese medicine formulas containing Bletilla can inhibit tyrosinase activity and possess antioxidant properties, thus resulting in skin-whitening effects[108]. Furthermore, some research reveals that the polysaccharides in the plant exhibit significant antioxidant activity, effectively scavenging free radicals and inhibiting tyrosinase activity[33]. This highlights the skin-whitening potential of the fibrous root of Bletilla striata, indicating promising prospects for the comprehensive utilization of the B. striata plant[33]. However, most studies on the pharmacological activities of Bletilla have focused solely on B. striata, neglecting other species within the genus. Different species may possess varying phytochemical compositions and antioxidant properties, which can lead to an incomplete understanding of the genus as a whole.

    Available hemostatic agents are expensive or raise safety concerns, and B. striata may serve as an inexpensive, natural, and promising alternative[109]. Polysaccharides of B. striata displayed hemostatic activity through inhibition of the NLRP3 inflammasome[110112]. The ADP receptor signaling pathways of P2Y1, P2Y12, and PKC receptors may be activated as part of the hemostasis[113]. Alkaloids from Bletilla have hemostatic activities through platelet deformation, aggregation, and secretion. In addition, polysaccharides of Bletilla striata have potential wound-healing medicinal value[110]. Currently, Bletilla plants have been used in various traditional systems, such as traditional Chinese medicine and Ayurveda, to control bleeding.

    Previous studies revealed that Bletilla displayed antibacterial effects[114]. For example, bletistrin F, showed inhibitory activities with MIC of (3–28 μg/mL) against S. aureus ATCC 6538[115,116]. Antimicrobial screening of Bletilla showed S. album (0.10%), A. capillaris (0.10%), and C. cassia (0.10%) to have the strongest antibacterial properties[117,118]. In addition, phenanthrenes are worthy of further investigation as a potential phytotherapeutic agent for treating infections caused by S. aureus and MRSA[119]. However, further in vivo studies on the antibacterial activity of Bletilla are lacking, which is needed for clinical application. For example, the specific mechanism of antibacterial activity of Bletilla still needs to be elucidated. While research on the antibacterial activity of Bletilla plants is promising, it faces several shortcomings and challenges that need to be addressed for a more comprehensive understanding of their potential therapeutic applications. Further studies with standardized methodologies, mechanistic insights, clinical trials, and consideration of ecological and safety concerns are essential to advance this field.

    There are other pharmacological activities of Bletilla, like anti-fibrosis activity, anti-adhesive activity, and immunomodulatory activity. For example, B. striata has been studied as a new and cheaper antiadhesive substance which decreased the development of abdominal adhesion abrasion-induced model in rats[120]. However, the natural resources of Bletilla are also getting scarcer. To preserve the sustainable development of Bletilla species, proper farming practices are required, along with the protection and economical use of these resources. The immunomodulatory activity of the Bletilla species was assessed using the 3H-thymidine incorporation method test, and BSP-2 increased the pinocytic capacity and NO generation, which improved the immunomodulatory function[121,122].

    B. striata extract was shown to have anti-pulmonary fibrosis effect[123]. B. striata polysaccharide can successfully prevent lung fibrosis through established by invasive intratracheal instillation method and evaluated by lung indexes[123,124]. Moreover, Bletilla species need further investigations to evaluate their long-term in vivo and in vitro activity before proceeding to the development of pharmaceutical formulation.

    While there is currently a deep understanding of the pharmacological activity of plants in the Bletilla genus, there are still many gaps that need to be addressed. To overcome these shortcomings, future research on the pharmacological activity of Bletilla species should emphasize comprehensive, well-designed studies with a focus on species-specific effects, mechanistic insights, and rigorous clinical trials. Additionally, collaboration among researchers, standardization of methods, and transparent reporting of results can help advance our understanding of the therapeutic potential of Bletilla plants. Researchers should also consider safety aspects and explore potential herb-drug interactions to ensure the responsible use of Bletilla-based therapies.

    There are several common clinical applications of Bletilla striata in TCM. The gum of B. striata has unique viscosity characteristics and can be used as thickener, lubricant, emulsifier and moisturizer in the petroleum, food, medicine, and cosmetics industries[125130]. B. striata is used as a coupling agent, plasma substitute, preparation adjuvant, food preservative and daily chemical raw material[131133]. In clinical practice, B. striata glue has also been proven to control the infections and is beneficial to the healing of burns and wounds[133135].

    In ethnic communities in Southwest China, the locals chew fresh Bletilla tubers directly or take them orally after soaking in honey to treat cough, pneumonia and other diseases[33, 34]. This traditional use is common in local communities in Southwest China, and suggests at the safety of Bletilla. However, current research shows it is still necessary to control the dosage when using Bletilla[136].

    Zebrafish embryos and larvae respond to most drugs in a manner similar to humans[137]. Militarine, the main active ingredient of Bletilla, was tested in a zebrafish embryo development assay at concentrations of 0.025 g/L and 0.05 g/L, and with the increased concentration, the heart rate of zebrafish embryos is slowed. Mortality and malformation rates of zebrafish embryos gradually increased with time and militarine concentration[138]. Although Bletilla species are safe at therapeutic dose ranges, further research on their safety is required[136]. More in-depth studies should be carried out on Bletilla to extract effective ingredients and make better preparations for clinical use[139].

    According to the traditional medicinal knowledge in ancient Chinese texts, Bletilla has been an important ingredient for skin care since ancient times. Many ethnic minority groups in China still retain the practice of using Bletilla for skin care, and the plant parts and preparation methods of use are consistent with the records in ancient texts. Almost 300 phytochemicals have been identified from Bletilla, and some of them possess important pharmacological activities, which support its traditional uses and suggest the important medicinal development potential of this genus. This review has demonstrated that Bletilla, as an important medicinal plant of Orchidaceae, still requires further research to fathom its medicinal potential.

    For instance, it is necessary to enhance the quality control procedures based on the chemical components and pharmacological activity of Bletilla. The chemical composition and pharmacological properties of Bletilla are critical areas of current research. According to previous studies, the main bioactive components of Bletilla can vary greatly according to its origin, harvest time, distribution, storage, and adulteration. However, variation in bioactivities caused by the differences in Bletilla constituentshave not been explored extensively yet. To develop clinical applications of Bletilla, it is crucial to further explore the mechanism of action between its chemical composition variation and its pharmacological actions.

    In addition, although the tuber has historically been the main medicinal part of Bletilla, research has shown that the chemical composition in other parts of Bletilla, such as stems, leaves, and flowers, also give these parts a variety of pharmacological activities. Further in-depth analysis of the chemical components and pharmacological activities of different parts of this genus is worthwhile, to explore the specific chemical basis of its pharmacological activities, develop related drugs, and promote clinical applications. For example, Bletilla polysaccharide has good hemostasis and astringent wound effects[110], so it may have the potential to be developed into a drug or related medical materials to stop bleeding and heal wounds.

    Finally, as a cautionary note, many unrestrained collections and the destruction of habitats have made the resources of wild Bletilla rarer. In addition to protecting the wild populations of Bletilla, appropriate breeding techniques should be adopted to meet the commercial needs of this economically important genus, thereby allowing its sustainable use in commerce.

    The authors confirm contribution to the paper as follows: study conception and design, funding acquirement: Long C; data analysis, draft manuscript preparation, literature review: Fan Y, Zhao J; manuscript revise and language editing: Wang M, Kennelly EJ, Long C. All authors reviewed the results and approved the final version of the manuscript.

    The raw data supporting the conclusion of this article will be made available by the authors, without undue reservation, to any qualified researcher. Requests to access these datasets should be directed to Yanxiao Fan (fanyanxiao0510@163.com).

    This research was funded by the Yunnan Provincial Science and Technology Talent and Platform Plan (202305AF150121), Assessment of Edible & Medicinal Plant Diversity and Associated Traditional Knowledge in Gaoligong Mountains (GBP-2022-01), the National Natural Science Foundation of China (32370407, 31761143001 & 31870316), China Scholarship Council (202206390021), and the Minzu University of China (2020MDJC03, 2022ZDPY10 & 2023GJAQ09).

  • The authors declare that they have no conflict of interest.

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  • Cite this article

    Świątek IM, Adamska-Szewczyk A. 2024. An overview of the potential use of plants in oral care products. Medicinal Plant Biology 3: e015 doi: 10.48130/mpb-0024-0015
    Świątek IM, Adamska-Szewczyk A. 2024. An overview of the potential use of plants in oral care products. Medicinal Plant Biology 3: e015 doi: 10.48130/mpb-0024-0015

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An overview of the potential use of plants in oral care products

Medicinal Plant Biology  3 Article number: e015  (2024)  |  Cite this article
An Author Correction to this article was published on 29 November 2024, http://doi.org/10.48130/mpb-0024-0030.

Abstract: Problems such as periodontal disease, tooth decay, and oral candidiasis are common conditions that affect people of all ages and geographical zones. They are often associated with poor oral hygiene. Pathogenic microorganisms, their metabolic activity, and inflammation are considered to be the basis of their formation. The search for active substances, components of oral care products, and hygiene products expands this possibility to include research on plant substances with antibacterial, antifungal, and anti-inflammatory properties. Plant extracts such as Rhamus prinoides, Pongamia pinnata, Myrmecodia pendens, Eichhornia crassipes, or the well-known propolis or coffee can effectively reduce the formation of dental plaque and protect against periodontitis. The effect of reducing tooth decay has been demonstrated in relation to extracts from plants such as: Stachytarpheta cayennensis, Mentha spicata, Piper crocatum, Mentha × piperita, Eucalyptus globulus, Clitoria ternatea, Stryphnodendron adstringens, Carum copticum, Phlomis bruguieri, Marrubium parviflorum and Prosopis africana. Rosmarinus officinalis, Punica granatum, Rosa centifolia, Curcuma longa, numerous essential oils (sage, mint, lavender, thyme, hyssop, oregano, lemongrass and others) and other known aromatic plants (including cloves, cinnamon, or Citrus paradisi) had anti-yeast properties. This study aimed to present an up-to-date review of the literature in relation to the latest research and possible potential sources of biologically active plant ingredients for use in preparations, both in prophylaxis and oral hygiene.

    • Oral hygiene is an extremely important aspect of human life. The first oral care products have been around for thousands of years. Ancient Egyptians used dental cream with ashes from oxen hooves and egg shells. Persians added burnt shells of snails, herbs, and honey. At the same time in China, people formulated their toothpaste with a flavor using ginseng, and herbal mints[1].

      The mouth is the first section of the digestive system (Fig. 1). There, food is mechanically broken down and mixed with saliva, which has an enzyme - salivary amylase. The most exposed to weakening agents is tooth enamel. Sugars and acids in food, as well as improper oral care, can lead to demineralization – which leads to tooth decay, or too much mineralization, with the symptom being the build-up of dental calculus. The main purpose of good oral hygiene is to provide a reduction in bacteria, proper pH, get rid of food debris, and dental plaque and strengthen teeth. Fourty five percent of the world's people have oral disease problems, and the number has been rising steadily for the past 30 years. The greatest increase in incidence is observed in low- and middle-income countries. An interesting fact is that oral health seems to be taken for granted, however, this aspect is neglected on a global level. The best treatment is prevention and prophylaxis[2]. Therefore, the development of cosmetic chemistry should also include oral hygiene products.

      Figure 1. 

      Drawing showing labels pointing to teeth, gums, roof of the mouth, bottom of the mouth, tongue, and inside of the cheek[3].

      Natural cosmetics continue to grow in popularity. In 2019, the global market for natural cosmetics was worth US$36 billion and is projected to be worth about US$54 billion in 2027[4]. Growing environmental concerns among consumers are prompting manufacturers to look for raw material alternatives. Another aspect is also the trend of a return to nature, a return to ancient healing methods that, before the development of the industry, were as effective as mass-obtained products (Fig. 2).

      Figure 2. 

      Return to the methods of folk medicine through increased consumer awareness.

      Folk medicine is known for its wide range of proven healing methods. It mainly uses plants, which are a rich source of biologically active substances. Plant products, i.e. extracts, essential oils, decoctions, or tinctures, show antimicrobial, anti-inflammatory, analgesic effects. Raw materials extracted from plants can be active substances and carriers for other ingredients[5,6].

      Most oral diseases result from the formation of a bacterial biofilm. A biofilm is a complex community of microorganisms. It consists of cells and extracellular substances (polysaccharides, proteins, lipids, extracellular DNA). Biofilm formation begins with adhesion, whereby bacteria attach to a solid surface. The next step is the polyfusion of bacterial cells and the secretion of extracellular polymeric substances. This creates another layer of biofilm (Fig. 3)[7].

      Figure 3. 

      Biofilm formation scheme.

      Biofilm control methods are divided into physical, chemical, and biological. Phytochemicals contained in various plant parts biologically act on biofilm. They are inhibitors of the Quorum Sensing (QS) system, an intercellular communication mechanism that controls cell density-dependent gene expression. Active compounds from the plant material have an inhibitory effect on virulence factors and regulatory genes, as well as blocking pyocyanin biosynthesis and reducing the regulation of QS genes. This prevents the biofilm from forming properly[7].

      Within the European Union, a cosmetic product also with herbal ingredients must meet the requirements of Regulation (EC) No. 1223/2009 of the European Parliament and the Council of November 30, 2009, concerning cosmetic products. In the act, one can find several definitions and rules that must be met for the product to enter the EU market. There are also annexes to the Regulation, which, among other things, mention prohibited substances, substances that can be used under appropriate concentration limits, colorants, preservatives. In terms of the plant world, the Regulation's annexes contain information on which plants may not be used in cosmetic products[8].

    • Gum diseases represent the most common problem that patients go to visit a dentist with, which maybe associated or not with dental plaque. However, the most frequent periodontal disease is gingivitis, which is associated with growing plaque[9].

      Plaque is a soft layer covering the teeth. A significant part of dental plaque is made up of bacteria, i.e. grains, chopsticks, and filamentous bacteria. In addition, the plaque is also built by an organic substance called a matrix, in which microbes are also present. Growing plaque promotes the formation of tartar between teeth and in the gum gap[10].

      It is recognized that plaque is a biofilm formed by more than 700 species of bacteria.

      In the absence of lesions, these species live in symbiosis with our oral cavity. However, nutrition can alter the ecosystem that prevails in the oral cavity. Disruption of the ecology upsets the balance between microorganisms and host[11].

      An effective way to fight gingivitis may be to inhibit bacterial growth. That kind of action can be taken by designing preparations containing specific plant extracts. Al-Mujamamii & Al Waheb investigated the effect of Rhamus prinoides extract on Streptococcus mutans biofilm. R. prinoides is a plant rich in flavonoids, saponins, alkaloids, terpenoids, and tannins, which have antibacterial effects[12]. R. prinoides, belonging to the Rhamnaceae family[13]. The leaves of R. prinoides were extracted using a Soxhlet apparatus and 70% methanol, then purified with diethyl ether to obtain a solution with pH = 8. A mouthwash was prepared and used by the patients twice daily for 3 weeks. The antibacterial effect was evaluated by counting streptococci before and after treatment with the rinse and placebo. The results are shown in Table 1. The study presented showed that R. prinoides extract reduces the activity of S. mutans bacteria[12].

      Table 1.  Average number of S. mutans at the beginning and end of treatment for the trial with R. prinoides extract and for the control trial[12].

      Average no. of S. mutans at the beginning of therapy (CFU/mL) Average no. of S. mutans after therapy (CFU/mL)
      Research sample 14.23 × 10−5 ± 7.67 0.45 × 10−5 ± 0.28
      Control sample 13.79 × 10−5 ± 11.11 30.22 × 10−5 ± 33.57

      Mouthwashes can also be used to prevent gum disease. In this way, propolis extract was used in the research[14]. Propolis is a resinous material collected by bees[15]. Due to its therapeutic properties and the chemical compounds, it contains, it is used in medicine and dentistry[16]. It is a component rich in flavonoids, phenols, and aromatic compounds, due to it having an antibacterial effect. In the present study, 60 children aged 12 to 14 years old participated, who had no dental caries and had orthodontic braces for more than a month. Children were separated into two groups, where group A consisted of 40 children who were given mouthwashes with a product containing 5% propolis extract. Group B (the control group) consisted of 20 children who were given distilled water instead of mouthwash. The product was applied twice daily after meals, in 30-day cycles for 3 months. The study compared the average plaque index score. The results are presented inTable 2. Analyzing the data presented in it, it may be seen that the use of both rinse variants reduces the amount of plaque, but the preparation with 5% propolis extract has better results[14].

      Table 2.  Results of the mean values of the plaque index in both groups.

      Time of therapy Average plaque index
      Group A Group B
      Before mouth wash 1.493 ± 0.017 1.483 ± 0.027
      First day after mouth wash 1.493 ± 0.017 1.483 ± 0.027
      After 1 month 1.173 ± 0.045 1.293 ± 0.018
      After 2 months 0.853 ± 0.055 1.065 ± 0.049
      After 3 months 0.683 ± 0.050 0.795 ± 0.022

      In India, an herbal mouthwash was developed from a hydroalcoholic extract of Pongamia pinnata to combat the bacteria that cause gingivitis, i.e. S. mutans, Porphyromonas gingivalis, Staphylococcus and Lactobacillus[17]. P. pinnata is a plant found throughout India, which is a rich source of flavonoids and their derivatives. The seeds, seed oil, flowers, and stems yield caranjin, pongapin, pongaglabron, canugin, desmethoxycanugin, and pinnatine[18]. Dried powdered leaves (132 g) of P. pinnata were placed in the thimble of a Soxhlet apparatus and double the extraction process was carried out using 800 mL of a mixture of 70% ethanol and water in a 1:1 ratio, for 48 h. The resulting material was then evaporated at 70 °C for 8 h and dried. In addition to the leaf extract of P. pinnata, the essential oil of Mentha × piperita was also obtained. For this purpose, a steam distillation process was carried out in a Clevenger apparatus. The extract obtained contained: alkaloids, carbohydrates, glycosides, saponins, phytosterols, resins, terpenoids, phenols, tannins, and flavonoids. Three formulations of herbal mouthwash differing in the content of P. pinnata leaf extract (250, 500, 1,000 mg) were prepared. The other ingredients used are: peppermint oil (0.1 mL), saccharin (0.1 mg), PEG-40 (4 g), glycerol (8.5 mL), salt solution (2 mL), Lemon Yellow Color (1−2 drops) and purified water (up to 100 mL). The resulting formulations were compared with a commercially available formulation with chlorhexidine. It turned out that formulation 2 had similar parameters to the commercial liquid. However, the cited study did not test for plaque inhibitory activity. This provides an opportunity for further in vitro and in vivo studies of P. pinnata leaf extract in other formulations and oral hygiene products.

      Inhibition of growth of pathogenic bacteria (P. gingivalis, A. actinomycetemscomitans, and S. viridans) by coffee bean extract was studied by Sari et al.[19]. The antibacterial properties of coffee result from the presence of compounds such as flavonoids, caffeine, trigonelline, or chlorogenic acid[19]. Coffee comes from the Rubiaceae family[20]. It is characterized by a neutral, weak flavor with a pronounced bitterness[21]. The chemical composition of robusta coffee depends on the growing region, but we can distinguish chemical compounds, i.e.: diterpenes (e.g. cafestol, 16-O-methylcafestol), sterols (e.g. β-sistosterol, 24-methylencycloartanol), tocopherols (γ-tocopherol)[22,23]. Robusta coffee extract was prepared by macerating coffee beans in 96% ethanol in a ratio of 1:5 for 72 h. The macerate was then filtered and the solvent evaporated. Aqueous solutions have been prepared from the extract obtained at the following concentrations from 50% to 6.25%. The resulting extracts were applied to paper discs. The bacterial colony was prepared on an agar medium. The discs with the extracts were placed in the bacterial colonies and the diameter of the growth inhibition was measured. The results of the studies are presented in Table 3. The study showed that Robusta coffee extract has an antibacterial effect from 12.5%[19]. Such results allow testing of the extract in specific oral hygiene products.

      Table 3.  Results of the mean periopathogenic bacterial growth inhibition zone with standard deviation after using Robusta coffee extract at different concentrations.

      Concentration
      of Robusta
      coffee extract
      Mean growth inhibition zone [mm] +
      standard deviation
      P. gingivalis A.
      actinomycetemcomitans
      S. viridans
      0% (control test) 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00
      6.25% 0.00 ± 0.00 0.00 ± 0.00 0.00 ± 0.00
      12.50% 13.14 ± 0.24 8.40 ± 0.22 12.15 ± 0.25
      25.00% 16.59 ± 0.17 12.20 ± 0.10 14.95 ± 0.10
      50.00% 19.18 ± 0.18 16.15 ± 0.12 18.15 ± 0.19

      Inflamed gums require antimicrobial action in the periodontal pockets. For this purpose, researchers set out to test the efficacy of Sarang Semut (Myrmecodia pendens) extract as an ingredient in an irrigation and mouthwash solution[24]. It grows in Sumatera, Papua New Guinea, the Philippines, Cambodia and Malaysia[25]. The composition of M. pendens includes glycoside, flavonoids, tocopherols, polyphenols, and tannins[26]. In the present study, male rats (Rattus norvegicus) aged 4−6 months were used. The plant was powdered and then macerated in 96% ethanol for 5 d. A 1% Carboxymethylcellulose Sodium (NaCMC) solution was used as a control preparation. Rats were divided into four groups (five individuals in each group). Observation followed within 3 h of administration of the preparation. The study showed minimal toxicity of M. pendens extract at a dose of 0.1 g/kg body weight to the kidneys and livers of the test rats. It was concluded that there is a need to test a lower dose of the extract ultimately in mouthwash preparations and the results obtained may be a reference for further studies[24].

      Other scientists have investigated the activity of water hyacinth (Eichhornia crassipes) leaf extract against bacteria found in the plaque of patients suffering from gingivitis[27]. The water hyacinth is a perennial floating plant. It competes with domestic aquatic plant species by completely covering the surface of water reservoirs[28]. The phytochemical composition of water hyacinth includes numerous secondary metabolites: polyphenols, flavonoids, fatty acids, alkaloids, sterols. The leaves contain phosphatidylethanolamine, phosphatidylcholine, and phosphatidylglycerol and are rich in lecithin, asparagine, and glutamine[29]. Water hyacinth leaf extract was used in the study, which was obtained by maceration in 70% ethanol, filtration on a Büchner funnel, and evaporation on a rotary evaporator using a water bath. Antimicrobial activity was checked by counting the number of microbial colonies on Mueller Hinton Agar (MHA). Microorganisms were extracted from the plaque of patients aged 20−30 years with gingivitis. The extracts tested had concentrations ranging from 100% to 0.78%. The study showed that water hyacinth extract inhibited the growth of plaque bacteria already at a concentration of 3.125%[27].

    • Dental caries are a chemical localized decay of the tooth surface that is caused by the metabolic activity of microorganisms in the biofilm. These microorganisms transform sugars supplied with food, converting them into acid. The product of microbial metabolism demineralizes the tooth enamel. The carious lesions themselves develop in areas where biofilm can accumulate and mature[30]. S. mutans has long been considered the caries-causing bacterium because it produces lactic acid and also increases at low pH values. In addition to S. mutans, there are other species of acid-producing microorganisms. These include bacteria from the types Veillonella, Scardovia, Propionibacterium, as well as other Streptococci that grow at acidic pH[31].

      One of the most effective ways to prevent tooth decay is through good oral hygiene, by brushing and flossing. Unfortunately, mechanical removal of biofilm, is not enough. There is a need to include additional substances in hygiene to counteract biofilm formation. One such substance is chlorhexidine dihydrochloride, but regular use leads to unwanted effects. For this reason, the essential oil of the leaves of Stachytarpheta cayennensis was used as an alternative medicine in studies described by Oliveira et al.[32]. S. cayennensis is a plant that can be found in tropical climates. In Brazil, its leaves are used in folk medicine as an anti-inflammatory, analgesic, antipyretic, constipation, and liver and kidney disorders. This study investigated the antibacterial properties of essential oil against decay bacteria. Fresh leaves of S. cayennensis were a source of essential oil, which was obtained from the plant material by hydrodistillation in a Clevenger apparatus (400 g leaves and 500 mL distilled water). The activity of the essential oil from S. cayennensis against decay bacteria was tested by microdilution in broth. The bacterial strains used were Streptococcus mutans, Streptococcus mitis, Streptococcus salivarius, Streptococcus sanguinis, Streptococcus sobrinus, Enterococcus faecalis, and Lactobacillus casei, which were cultured on agar medium. The essential oils were dissolved in Dimethyl Sulfoxide (DMSO). The positive control was chlorhexidine dihydrochloride placed in broth. The study showed the activity of S. cayennensis leaf essential oil against the bacteria S. mutans, S. mitis, S. salivarus, and S. sobrinus[32]. The results of this study show the potential for the use of S. cayennensis essential oil in oral care products and encourage further research.

      Another publication examined the effects of Mentha spicata and Eucalyptus globulus essential oils on S. mutans biofilm[33]. M. spicata is otherwise known as spearmint. Cultivation concentrated on essential oil production is located in the USA[34]. The predominant component of the oil is carvone (40%−76%). In addition, limonene, 1,8-cyneol are found in the oil. E. globulus is a tree that reaches up to 60 m in height. The main component of the oil is 1,8-cineole, which can be up to 84%[35]. Evaluation of the inhibitory activity of the oils was determined by agar well diffusion and calorimetric microdilution methods. In contrast, activity against biofilms was determined on pieces of bovine enamel using Buffered Minimal Methanol (BMM) medium under anaerobic conditions with daily exposure to sucrose to mimic oral conditions. Essential oils were applied at a concentration of 0.4% in saline solution with 1% polysorbate-20. The study showed a significant reduction in biofilm after 72 h. This was assessed by turbidity of the suspension and microbial counts. The studies discussed here demonstrated the efficacy of both essential oils[33]. This provides an opportunity for further research into the oils and testing their antimicrobial activity in oral hygiene preparations.

      Butterfly pea (Clitoria ternatea Linn.) extract has also shown activity against Streptococcus mutans. Butterfly pea flower is used in Ayurvedic medicine[36]. C. ternatea contains antifungal compounds, i.e. taraxerol, taraxerone, p-Hydroxycinnamic acid, β-sitosterol, delphinidin, kaempferol, clitorin[37]. In a study conducted in Indonesia, an ethanolic (70% ethanol) extract of C. ternatea was used. In vitro tests were carried out using the diffusion method, using 12 test groups of 4-fold replicates. A 0.2% chlorhexidine solution (positive) and distilled water (negative) were used as control groups. Aqueous solutions of the extract were then prepared at concentrations ranging from 10% to 90%. S. mutans bacteria were cultured on Brain Heart Infusion Broth (BHIB) medium (at 37 °C under anaerobic conditions for 24 h) and then bacteria were cultured in a petri dish containing MHA. Samples were divided into control (positive and negative) and test groups. Inhibition of bacterial growth was shown at concentrations of 50% and above, but the best result was obtained for the pure extract. This is an expected result, as the pure extract contains the highest concentration of active substances[36]. The study found that an extract from C. ternatea could be an ingredient in caries prevention products.

      In Indonesia explored the antibacterial properties of Piper crocatum Ruiz & Pav. and Mentha × piperita extracts as toothpaste ingredients. The anti-caries ingredient in the pastes is fluoride, but it cannot be used in pastes for children under 4 years of age. In addition, the use of fluoride in excess can lead to osteoporosis and damage to the nervous system. The study described here aimed to find an alternative to fluoride[38], P. crocatum Ruiz & Pav. This is one of the more popular plants used in herbal therapies in Indonesia[39]. P. crocatum is rich in tannins, saponins, alkaloids, and flavonoids[40]. Mentha × piperita is a triple hybrid of M. aquatica and M. spicata. It has reddish-purple stems. It is used most commonly in gastrointestinal disorders and as a taste and odor enhancer[34]. In the present study, extracts of Piper crocatum Ruiz & Pav. and Mentha × piperita were prepared. The extracts were prepared by maceration in 70% ethanol for 24 h, filtration, and evaporation using a vacuum evaporator. The resulting extracts were used in five toothpaste formulations. A zone of inhibition of S. mutans bacterial growth was observed in the study. The microorganisms used in the study were cultured on an agar medium. Five test groups, a negative control (toothpaste without plant extracts), and a positive control (herbal toothpaste) were then prepared. The test materials were incubated for 24 h at 37 °C. Studies have shown the effectiveness of a paste containing two extracts in its composition in concentrations: 10% of both extracts, 15% of P. crocatum extract and 5% of Mentha × piperita extract, 5% of P. crocatum extract and 15% of Mentha × piperita extract[38].

      Another study under discussion was conducted in Brazil. An article by Camilo et al. investigated the antimicrobial properties of extract of Stryphnodendron adstringens[41]. The stem bark is commonly used medicinally for its anti-inflammatory and antimicrobial properties[42]. S. adstringens is a rich source of alkaloids, terpenes, flavonoids, steroids, and tannins[43]. The researchers prepared an extract from the dried leaves of S. adstringens by maceration in 95% ethanol (process time: 7 d), followed by concentration at 50 °C using a rotary evaporator[41,44]. The Kirby-Bauer plate diffusion method was used to determine the value of the minimum inhibitory concentration. The following bacterial cultures were used in the study: Enterococcus faecalis, Lactobacillus casei, Streptococcus mitis, S. mutans, S. salivarius, S. sanguinis, S. sobrinus. DMSO solutions at concentrations ranging from 1 to 10% were used as the negative control in the study, and chlorhexidine digluconate solutions at concentrations ranging from 0.015 to 5.9 mg/mL were used as the positive control. S. adstringens extract was tested at dilutions from 50 to 500 mg/mL. Bacterial cultures were developed on broth medium in plates. The previously mentioned solutions were added to the prepared colonies. Each sample was incubated at approximately 35 °C for 24 h. After incubation, 0.01% resazurin (30 μL) was added to the samples so that microbial growth could be observed immediately. Blue coloring indicated no growth and red coloring indicated microbial growth. The results showed that the extract from S. adstringens has activity against decay bacteria[41].

      The efficacy of three plant extracts of S. mutans compared to a 0.2% Chlorhexidine solution is described in an article by Mehdipour et al.[45]. The first plant discussed in the study is Carum copticum. Ajwain (C. copticum) is a plant of the Apiaceae family. The seeds contain carbohydrates, fats, proteins, fiber, tannins, glycosides, saponins, and minerals[46]. The second plant was Phlomis bruguieri. It is a plant belonging to the Lamiaceae family. It exhibits antioxidant and antimicrobial activities. It is a rich source of flavonoids and glycosides[47]. The last plant used in the study by scientists was Marrubium parviflorum. It is used in folk medicine as an antipyretic[48]. The phytochemical composition of M. parviflorum may include diterpenes, caffeic acid derivatives, as well as sterols and flavonoids[49]. Methanolic extracts were prepared from the plants discussed by maceration. The agar well diffusion method using DMSO was used to assess antimicrobial activity. Bacteria were cultured on BHI agar medium. The wells in the agar used for testing were filled with extracts at concentrations ranging from 0.390 to 200 mg/mL and bacterial material. The positive control was 0.2% chlorhexidine solution and the negative control was DMSO. After incubation, the diameter of the inhibition zones was measured. The biofilm inhibition properties were then tested using the O'Toole's procedure. The standard medium for the S. mutans biofilm test was brain-heart infusion broth with 2% sucrose (BHIS). Bacterial suspension and extracts were placed in a microtiter plate at concentrations ranging from 0.39 to 200 mg/mL. The positive control was the wells filled only with the bacterial suspension and the negative control was the BHIS medium. The study discussed here showed antibacterial activity against S. mutans and antibiofilm activity against S. mutans. The effect on biofilm was lower than 0.2% chlorhexidine. There is a need for further studies on extracts from C. copticum, Phlomis bruguieri and M. parviflorum to see the in vivo effects[45].

      An article by Bance et al. describes research on the aqueous extract of Prosopis africana[50]. P. africana is a common tree that grows in arid and semi-arid areas of the world[51]. In traditional medicine, it is used to treat the oral cavity[50]. It is a source of flavonoids, steroids, alkaloids, and fatty alcohols[52]. The bacterial strains used in the study were S. mutans, Staphylococcus aureus, Pseudomonas aeruginosa, Chromobacterium violaceum. Each was stored in BHI liquid medium (S. mutans, S. aureus) and Lauria-Bertani (P. aeruginosa, C. violaceum) with 50% glycerol at −80 °C until use. The collected plant material was dried and then powdered. Extraction was carried out using powder and distilled water (time of process: 30 min). Then the extract was cooled, filtered through nylon cloth and concentrated in an oven. The whole mixture was lyophilized and sealed in airtight white vials. Anti-inflammatory activity was evaluated by lipoxygenase inhibitory activity. Oxidative properties were evaluated by the radical cation decolorization method and antibiofilm activity was tested using crystal violet and solution absorbance studies. The study showed an inhibitory effect of P. africana extract on the growth of bacterial biofilm, which justifies the use of this plant in folk medicine for the treatment of dental diseases, including dental caries[50]. This of course creates opportunities for further investigation of P. africana in in vivo tests in cosmetic preparations.

    • Oral candidosis is the most common fungal diseases of the oral cavity. It is caused by the fungus Candida spp. in particular Candida albicans[53]. C. albicans belongs to the oral microflora and approximately 30%−50% of the population is a carrier of this organism, with the frequency of being a carrier increasing with age[54]. Candidiasis is commonly referred to as 'thrush'. It involves infections of the tongue and other areas of the mucosa. The characteristic feature is fungal overgrowth and invasion of tissue surfaces. Candidiasis was already known at the time of Hippocrates, who wrote about it in his book 'Of the epidemics'[55]. The disease itself is due to lowered immunity, use of antibiotics, steroids[53,56]. Contributing to the search for alternative treatments has been the overuse of fluconazal, to which the Candida species have begun to become immune[57].

      The antifungal properties of glycolic plant extracts were investigated in an article by Meccatti et al. Extracts from Rosmarinus officinalis, Punica granatum, Rosa centifolia, and Curcuma longa were used in the study[57]. Rosemary (Rosmarinus officinalis) is an aromatic plant belonging to the Lamiaceae family. In folk medicine, it has been used as an oral remedy to relieve renal colic, painful menstruation, and muscle spasms. It is characterized by antifungal, antiviral, antibacterial, and anti-inflammatory properties, among others. R. officinalis is a rich source of flavonoids, polyphenols, and terpenes[58]. The pomegranate (Punica granatum) is a small tree. Each part of the pomegranate has different pharmacological properties and is the source of a wide range of active ingredients such as ellagitannins, gallotannins, ellagic acid derivatives, catechins, and many others[59]. Rosa centifolia L. is a perennial plant, belonging to the Rosaceae family. It is a hybrid of varieties such as Rosa gallica L., Rosa moschata Herrm., Rosa canina L., and Rosa damascene Mill. In traditional medicine it has found use in the treatment of arthritis, coughs, asthma, bronchitis, wounds, and ulcers[60]. Turmeric (Curcuma longa) is a medicinal herb in the Zingiberaceae family. It is used as a spice but has also found use in folk medicine due to its medicinal properties. It is characterized by its antibacterial, anti-inflammatory action. These effects are attributed to a compound present in turmeric – Curcuminoids[61]. In the study in question, the researchers examined, using High-Performance Liquid Chromatography (HPLC), which active ingredients were present (Table 4). Mixtures of extracts were used: R. centifolia + C. longa and R. officinalis + P. granatum against C. albicans, C. dubliniensis, C. tropicalis, and C. krusei. It was shown that C. albicans biofilm significantly decreased after application of the extracts[57].

      Table 4.  Active compounds detected by HPLC from plant extracts (Rosmarinus officinalis, Punica granatum, Rosa centifolia, and Curcuma longa).

      Plant Rosmarinus officinalis L. Punica granatum L. Rosa centifolia L. Curcuma longa L.
      Active ingredients Gallotannin, chlorogenic acid,
      p-coumaric acid
      Gallotannin, quercetin or kaempferol Gallic acid, gallium, p-coumaric acid, derivative of quercetin Curcumin

      In India, research has been conducted on the antifungal activity of grapefruit extract. This study evaluated the effect of the volatile oil extract of grapefruit leaves against Candida species[62]. Citrus paradisi (grapefruit) belongs to the Rutaceae family[63]. Grapefruit is a natural cross between sweet orange and pomelo[35]. The active compounds present in the essential oils of C. paradisi are terpenes, sesquiterpenes, aldehydes, alcohols, esters, and sterols[64]. The oil was obtained from the leaves of grapefruit trees by hydrodistillation in an aqueous-glycerol solvent in a Clevenger apparatus. The antifungal properties of the raw material were tested on Candida albicans, Candida krusei, Candida tropicalis, and Candida parapsilosis strains. The zone of inhibition of microbial growth was determined by a dilution technique in broth, using oils at concentrations of: 100% and 50% to 3.75%. A cytotoxicity test was then performed on human gingival fibroblasts. The tests carried out showed the efficacy of grapefruit oil on Candida fungi in the following order: Candida parapsilosis > Candida krusei > Candida tropicalis > Candida albicans. The results obtained for Candida albicans and Candida krusei showed greater activity of the extract than the commercially available Amphoreitin B[62].

      In an article by Proškovcová et al. describes research on the antifungal and antibiofilm effects of five essential oils (Salvia officinalis, Thymus vulgaris, R. officinalis, Origanum vulgare, and Hyssopus officinalis)[65]. Sage (Salvia officinalis) is a perennial shrub in the Labiatae/Lamiaceae family[66]. Salvia essential oil is used for inflammation and infections of the mucous membranes of the throat and mouth. S. officinalis is a rich source of metabolites with healing properties, e.g. α- and β-thujone, 1,8-cineole, camphor, carnosic acid, oleanoic and ursolic acids or phenolic compounds[67]. Thyme (Thymus vulgaris) is a spicy herb in the Lamiaceae family native to southern Europe. Thyme has been used for centuries as a flavoring, spice, and in herbal medicine[68]. The essential oil from Thymus vulgaris has a broad spectrum of antimicrobial activity. The main constituents of the oil such as p-cymene and thymol show strong antifungal activity[69]. Rosemary essential oil is obtained from rosemary. It is usually obtained by steam distillation of fresh leaves. Its composition depends on the chemotype of the raw material. There are three chemotypes: camphor, 1,8-cineol, and verbena. The oil can contain eucalyptol, camphor, α-pinene, borneol, and verbenone in its composition[35]. Oregano (Origanum vulgare) is another member of the Lamiaceae family. It has been used in folk medicine to treat respiratory disorders, digestive disorders, and as an ointment for wounds. The essential oil is extracted from the stems, leaves, and flowers. It is a rich source of phenolic compounds, flavonoids, tannins, and polysaccharides[70]. Hyssop (Hyssopus officinalis) is also a representative of the Lamiaceae family. In herbal medicine, it was used to treat coughs and stomach diseases. The essential oil extracted from H. officinalis has a variable composition depending on its growing regions. The oil may include cis-pinocamphene, elemol, β-pinene, and 1,8-cyneol. It is characterized by antiviral, antibacterial and antifungal activity. Previous studies have shown its efficacy against Candida sp.[71]. In the study in question, Slovak researchers determined the antifungal properties of each of these essential oils in the concentration range of 200−0.4 mg/mL on C. albicans cells. The study used 13 C. albicans isolates from clinical patients with suspected candidiasis. In addition, each oil was evaluated for biofilm inhibition efficacy. A crystal violet test was used. The effect of essential oils on inhibiting biofilm growth was determined for the following concentration ranges: 25−0.05 mg/mL for Origanum vulgare, H. officinalis and T. vulgaris; 200−0.4 mg/mL for S. officinalis and 100−0.2 mg/mL for R. officinalis. Essential oils at the indicated concentrations and 100 μL SG were added to the wells of the yeast microtiter plate. Results were obtained after 48 h of incubation. Studies have shown that each of the essential oils in question has antifungal and antibiofilm activity. Oil of oregano has proven to be the best alternative for the treatment and complementary therapy of mycoses. Thyme oil, on the other hand, showed potential in the prevention and treatment of mycoses. The whole study encourages further research[65].

      In an article by Alves-Silva et al. also decided to investigate the anti-biofilm properties of an essential oil. They chose lavender oil to test the potential against strains of dermatophytes and C. albicans[72]. Lavender (Lavandula multifida L.) is a perennial plant belonging to the Lamiacea family. Lavender is used to obtain essential oil. Its composition varies depending on the part of the plant and the place of cultivation. The oil may contain the following compounds: carvanol, linalool, 1-octen-3-ol, carvacrol, anethole, bisabolene[73]. The lavender oil used in the study was obtained by hydrodistillation. The antibiofilm activity of lavender essential oil was tested on yeasts and filamentous fungi. The dermatophytes used were Microsporum gypseum, Trichophyton mentagrophytes var. Interdigitale, T. rubrum, Epidermophytom floccosum, M. canis, T. mentagrophytes; and yeast: C. albicans. Biofilm mass, extracellular matrix and viability were examined quantitatively using crystal violet, safranin and XTT assays. In contrast, morphological changes were confirmed by optical and scanning microscopy. The results proved that lavender oil showed a strong inhibitory effect on the biofilm formation of both dermatophytes and C. albicans. In addition, the oil showed the ability to eliminate mature biofilm[72].

      Essential oils were also chosen for testing in an article by Shah et al. Scientists selected four essential oils to test their properties against Candida yeast[74]. One of the oils was lemongrass (Cymbopogon citratus) essential oil. C. citratus belongs to the Poaceae family[75]. The main constituent of C. citratus essential oil is citral, with up to 85%[35]. The second essential oil tested was cinnamon bark oil (Cinnamomum zeylanicum). Cinnamon is uses in Ayurvedic medicine, it is considered a remedy for respiratory and digestive diseases and is also used for gynecological ailments[76]. The main chemical compound of cinnamon bark oil is cinnamaldehyde[77]. The third oil was the oregano oil already discussed. The last of the essential oils was oil from Trachyspermum ammi (ajwain oil). It belongs to the Apiaceae family. It is characterized by its stimulant, windmilling, antispasmodic, and tonic properties. The main ingredient of ajwain oil is thymol, which has antibacterial properties and is also known for its healingprop-erties (e.g. for alleviating the symptoms of cholera)[35,78]. Each essential oil was prepared by hydrodistillation in a Clevenger apparatus. Microbiological material for the study was collected from 50 subjects with early childhood caries, oral candida, and removable dentures and orthodontic appliances. The study material was divided into eight groups: (1) ajwain essential oil; (2) cinnamon bark oil; (3) lemon grass oil; (4) oregano oil; (5) essential oil blends; (6) probiotics; (7) clotrimazole; (8) chlorhexidine. The efficacy of the aforementioned agents was tested against C. albicans using the agar well diffusion method (positive control: clotrimazole and chlorhexidine; negative control: DMSO), followed by testing the minimum inhibitory concentration (visual method with Alamar Blue dye). Studies have shown that selected essential oils can be used as antimicrobial agents against Candida[74].

      Sudanese researchers decided to test clove extract for antimicrobial activity and develop a suitable medicinal preparation to treat oral candidiasis[79]. Clove (Syzygium aromaticum) is a dried flower bud belonging to the Myrtaceae family. Cloves exhibit strong antimicrobial and antioxidant activity. Cloves are a source of phenolic compounds, flavonoids, and tannins[80]. The plant material was dried and extracted with 97% ethanol (process time: 24 h). The total was then separated from the solvent, filtered, and concentrated at 65 °C. To determine the antifungal potential on the yeast C. albicans of the clove extract, the agar well diffusion method was used. Pharmaceutical formulations were developed to determine the minimum concentration of the extract that would be effective against C. albicans. Formulations containing concentrations ranging from 25% to 100% of clove extract were tested. The positive control was 5 mg of amphocerin B. The gel formulation with the extract tested consisted of glycerol (15 mL), carboxymethylcellulose (5 g), sodium benzoate, vanillin (25 mL), sucrose syrup, polysorbate 20, and distilled water. To evaluate the antifungal efficacy of the resulting formulation, it was compared with an oral gel with miconazole. The diameters of the zones of inhibition were then measured. The study showed the efficacy of the developed gel, where the minimum concentration of clove extract was 25%[79].

    • Oral hygiene is a key part of taking care of your health. Over the years, the problem of oral diseases has become increasingly prominent. The growing industry and synthetic applications have made most pathogens resistant to commonly used preparations. This fact and the growing trend toward eco products have forced manufacturers of oral preparations to look for alternatives by drawing knowledge from folk medicine and hitherto unexplored substances of plant origin. This review presents the latest reports on the effectiveness of extracts, macerates, and essential oils used alone or in hygiene preparations in the fight against oral diseases.

      Gingival disease is primarily influenced by the growing bacterial biofilm that constitutes plaque. It has been proven that a good solution is to find substances that inhibit the pattern of biofilm. For this purpose, a good solution is to use rinses that will contain in their composition plant extracts that inhibit the development of biofilm and plaque.

      In the case of caries, results have been presented showing that appropriate essential oils inhibit the growth of S. mutans bacteria. In addition to antimicrobial properties, oils can impart flavor and aroma in formulations. In addition to OEs, plant extracts play a large role in the fight against S. mutans as in gingival diseases.

      In the treatment of what is commonly known as thrush, extracts and essential oils that show properties against the fungal growth of Candida sp. play an important role. As above, finding suitable plants offers great opportunities for the development of future formulations and a variety of market preparations.

      Active substances extracted from plants may also find other uses in addition to their inhibitory effect on microorganisms that cause oral diseases. Biocidal compounds contained in plants are also being studied for their toxic effects on organisms, i.e. insects. A paper by Xiao et al. gives an example of using a paste of Chinese herbs to test toxicity on imported red ants[81]. The findings are promising and show an interesting direction for today's researchers. At a time when environmental sustainability and ecology are of extreme importance, it is necessary to look for new solutions that work universally in different aspects.

      In summary, oral diseases are a problem affecting more and more people. It is the task of scientists as well as industry to draw knowledge from traditional therapeutic methods and seek new solutions using what the plant world gives us. This contributes to increasing sustainability and meeting consumer expectations.

      • This work was supported by Science Club: Substances of plant origin - research perspectives, potentials applications in the prevention and treatment of various diseases in University of Engineering and Health of Warsaw.

      • The authors confirm contribution to the paper as follows: writing and figure preparation: Świątek IM; review and editing: Adamska-Szewczyk A. Both authors reviewed, read, and approved the final version of the manuscript.

      • All data generated or analyzed during this study are included in this published article.

      • The authors declare that they have no conflict of interest.

      • Copyright: © 2024 by the author(s). Published by Maximum Academic Press, Fayetteville, GA. This article is an open access article distributed under Creative Commons Attribution License (CC BY 4.0), visit https://creativecommons.org/licenses/by/4.0/.
    Figure (3)  Table (4) References (81)
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    Świątek IM, Adamska-Szewczyk A. 2024. An overview of the potential use of plants in oral care products. Medicinal Plant Biology 3: e015 doi: 10.48130/mpb-0024-0015
    Świątek IM, Adamska-Szewczyk A. 2024. An overview of the potential use of plants in oral care products. Medicinal Plant Biology 3: e015 doi: 10.48130/mpb-0024-0015

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