Detection and analysis of the volatile components in the essential oils of <i>Chrysanthemum</i> and <i>Opisthopappus</i> species and their hybrid progeny

Hua Liu; Xiaoxi Chen; Hạixia Chen; Shuang Guo; Conglin Huang; Xiaowei Tang; Yin Jia; Hua Liu; Xiaoxi Chen; Hạixia Chen; Shuang Guo; Conglin Huang; Xiaowei Tang; Yin Jia

doi:10.48130/OPR-2022-0007

2022 Volume 2

Article Contents

Next Previous

ARTICLE Open Access

Detection and analysis of the volatile components in the essential oils of Chrysanthemum and Opisthopappus species and their hybrid progeny

1.
Institute of Grassland, Flowers and Ecology, Beijing Academy of Agriculture and Forestry Sciences, Beijing Engineering Research Center of Functional Floriculture, Beijing 100097, China
2.
College of Landscape Architecture, Sichuan Agricultural University, Chengdu 611130, China
3.
College of Landscape Architecture, Beijing University of Agriculture, Beijing 100097, China
4.
Chengdu Landscape Architecture Planning & Designing Institute, Chengdu Park City Research Center, Chengdu 610036, China
5.
Institute of Agri-food Processing and Nutrition (IAPN), Beijing Academy of Agriculture and Forestry Sciences, Beijing 100097, China
^# These authors contributed equally: Hua Liu, Xiaoxi Chen

More Information

Corresponding authors: conglinh@126.com; tangxiaowei@nercv.org; jiayin_cn@163.com

Received: 23 November 2021
Accepted: 01 March 2022
Published online: 25 April 2022
Ornamental Plant Research 2, Article number: 7 (2022) | Cite this article

Abstract

Chrysanthemum and Opisthopappus are genera that include perennial herbaceous floral species, including excellent varieties with strong fragrances resulting from long-term artificial selection. Thus, they are ornamentally and economically important flower resources. In this study, a water distillation method was used to extract essential oils from the inflorescences of Chrysanthemum and Opisthopappus wild resources and hybrid progeny with high essential oil contents (Chrysanthemum morifolium 'xiangjin', C. morifolium 'xiangyun', C. morifolium 'xinjiboju', Opisthopappus taihangensis, Opisthopappus longilobus, Chrysanthemum lavandulifolium, and C. morifolium 'minghuangju'). The essential oil extraction rates were as follows: 1.17‰, 2‰, 1.67‰, 2.17‰, 0.43‰, 1‰, and 1.17‰. On the basis of HS-SPME-GC-MS (Headspace solid phase microextraction-gas chromatography-mass spectrometry), 225 volatile compounds were detected in the seven analyzed essential oil samples. Each essential oil had a relative volatile component content exceeding 0.3. The three most abundant compounds were olefins (46 types), alcohols (34 types), and esters (18 types). The volatile components with relatively high contents included thymol, D-camphor, pinene, eucalyptol, 2-terpineol, terpineol, trans-caryophyllene, and β-elemene. These volatile compounds have strong biological activities and are useful components of medicines and daily-use products. An evaluation of their antibacterial effects demonstrated that the essential oils of C. 'xiangjin', C. 'xiangyun', C. 'xinjiboju', O. taihangensis, O. longilobus, and C. 'minghuangju' inhibited the growth of Escherichia coli. The C. lavandulifolium essential oil inhibited the growth of Pectobacterium carotovorum. The results of this study will provide researchers with an important theoretical basis for the development and application of Chrysanthemum and Opisthopappus essential oils.
- Chrysanthemum,
- Opisthopappus,
- Chrysanthemum essential oil,
- Volatile components,
- Essential oil function

Supplementary information

Supplemental Table S1 Essential oil extraction data.
Supplemental Table S2 Main components and relative contents of seven essential oils.

Rights and permissions
Copyright: © 2022 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/.

References

[1]	Shi Z, Fu G. 1983. Flora Republicae Popularis Sinicae (FRPS): Anthemideae Cass. Beijing: Science Press. vol 76, 73 pp.
[2]	Chen L, Hu D, Xu W, Li S, Zhao J. 2021. Identification and determination of fructooligosaccharides in snow chrysanthemum (Coreopsis tinctoria nutt.). World Journal of Traditional Chinese Medicine 7:78−85 doi: 10.4103/wjtcm.wjtcm_64_20 CrossRef Google Scholar
[3]	Guo R, Zhou L, Zhao H, Chen F. 2013. High genetic diversity and insignificant interspecific differentiation in Opisthopappus Shih, an endangered cliff genus endemic to the Taihang Mountains of China. The Scientific World Journal 2013:275753 doi: 10.1155/2013/275753 CrossRef Google Scholar
[4]	Wang Y. 2013. Chloroplast microsatellite diversity of Opisthopappus Shih (Asteraceae) endemic to China. Plant Systematics and Evolution 299:1849−58 doi: 10.1007/s00606-013-0840-8 CrossRef Google Scholar
[5]	Chu S. 1979. Opisthopappus Shih — A new genus of Compositae from China. Acta Phytotaxonomica Sinica 17:110−12 Google Scholar
[6]	Gu J, Wei Z, Yue C, Xu X, Zhang T, et al. 2019. The complete chloroplast genome of Opisthopappus taihangensis (Ling) Shih. Mitochondrial DNA Part B 4:1415−16 doi: 10.1080/23802359.2019.1598791 CrossRef Google Scholar
[7]	Guo Y, Zhang T, Zhong J, Ba T, Xu T, et al. 2020. Identification of the volatile compounds and observation of the glandular trichomes in Opisthopappus taihangensis and four species of Chrysanthemum. Plants 9:855 doi: 10.3390/plants9070855 CrossRef Google Scholar
[8]	Chai M, Ye H, Wang Z, Zhou Y, Wu J, et al. 2020. Genetic divergence and relationship among Opisthopappus species identified by development of EST-SSR markers. Frontiers in Genetics 11:177 doi: 10.3389/fgene.2020.00177 CrossRef Google Scholar
[9]	Gu H, Yang Y, Xing M, Yue C, Wei F, et al. 2019. Physiological and transcriptome analyses of Opisthopappus taihangensis in response to drought stress. Cell & Bioscience 9:56 doi: 10.1186/s13578-019-0318-7 CrossRef Google Scholar
[10]	Yang Y, Guo Y, Zhong J, Zhang T, Li D, et al. 2020. Root physiological traits and transcriptome analyses reveal that root zone water retention confers drought tolerance to Opisthopappustaihangensis. Scientific Reports 10:2627 doi: 10.1038/s41598-020-59399-0 CrossRef Google Scholar
[11]	Wang Y, Yan G. 2013. Genetic diversity and population structure of Opisthopappus longilobus and Opisthopappus taihangensis (Asteraceae) in China determined using sequence related amplified polymorphism markers. Biochemical Systematics and Ecology 49:115−24 doi: 10.1016/j.bse.2013.03.014 CrossRef Google Scholar
[12]	Wang H, Fang X, Ye Y, Cheng Y, Wang Z. 2011. High genetic diversity in Taihangia rupestris Yu et Li, a rare cliff herb endemic to China, based on inter-simple sequence repeat markers. Biochemical Systematics and Ecology 39:553−61 doi: 10.1016/j.bse.2011.08.004 CrossRef Google Scholar
[13]	Pei S, Cheng Y, Wang Y, Jiao Z, Wang H. 2015. Development and characterization of microsatellite loci in Opisthopappus taihangensis (Compositae), a rare herb endemic to China. Conservation Genetics Resources 7:269−71 doi: 10.1007/s12686-014-0354-x CrossRef Google Scholar
[14]	Wang Y, Zhang C, Lin L, Yuan L. 2015. ITS sequence analysis of Opisthopappus taihangensis and O. longilobus. Acta Horticulturae Sinica 42:86−94 doi: 10.16420/j.issn.0513-353x.2014-0400 CrossRef Google Scholar
[15]	Bakkali F, Averbeck S, Averbeck D, Idaomar M. 2008. Biological effects of essential oils – A review. Food and Chemical Toxicology 46:446−75 doi: 10.1016/j.fct.2007.09.106 CrossRef Google Scholar
[16]	Maciel MV, Morais SM, Bevilaqua CML, Silva RA, Barros RS, et al. 2010. Chemical composition of Eucalyptus spp. essential oils and their insecticidal effects on Lutzomyia longipalpis. Veterinary Parasitology 167:1−7 doi: 10.1016/j.vetpar.2009.09.053 CrossRef Google Scholar
[17]	Silva J, Abebe W, Sousa SM, Duarte VG, Machado MIL, et al. 2003. Analgesic and anti-inflammatory effects of essential oils of Eucalyptus. Journal of Ethnopharmacology 89:277−83 doi: 10.1016/j.jep.2003.09.007 CrossRef Google Scholar
[18]	Hajhashemi V, Ghannadi A, Sharif B. 2003. Anti-inflammatory and analgesic properties of the leaf extracts and essential oil of Lavan dula angustifolia Mill. Journal of Ethnopharmacology 89:67−71 doi: 10.1016/S0378-8741(03)00234-4 CrossRef Google Scholar
[19]	Perry NSL, Bollen C, Perry EK, Ballard C. 2003. Salvia for dementia therapy: review of pharmacological activity and pilot tolerability clinical trial. Pharmacology Biochemistry and Behavior 75:651−59 doi: 10.1016/S0091-3057(03)00108-4 CrossRef Google Scholar
[20]	Candy B, Armstrong M, Flemming K, Kupeli N, Stone P, et al. 2020. The effectiveness of aromatherapy, massage and reflexology in people with palliative care needs: A systematic review. Palliative Medicine 34:179−94 doi: 10.1177/0269216319884198 CrossRef Google Scholar
[21]	Carson CF, Mee BJ, Riley TV. 2002. Mechanism of action of Melaleuca alternifolia (tea tree) oil on Staphylococcus aureus determined by time-kill, lysis, leakage, and salt tolerance assays and electron microscopy. Antimicrobial Agents and Chemotherapy 46:1914−20 doi: 10.1128/AAC.46.6.1914-1920.2002 CrossRef Google Scholar
[22]	Carson CF, Riley TV. 2016. Non-antibiotic therapies for infectious diseases. Communicable Diseases Intelligence 27:S143−S146 Google Scholar
[23]	Woolf A. 1999. Essential oil poisoning. Journal of Toxicology Clinical Toxicology 37:721−27 doi: 10.1081/CLT-100102450 CrossRef Google Scholar
[24]	Chen W, Zheng X, Wang F, Zhang M, Xu L. 2017. SPME-GC-MC analysis of chemical components of essential oil from Tianmeng Mountain Imperial Chrysanthemum. Shandong Science 30:15−21 Google Scholar
[25]	Zhang Y, Feng Z, Zeng H. 2016. Essential oil composition of Coreopsis tinctoria Nutt. and anti-Cryptococcus activity. Microbiology China1304−14 doi: 10.13344/j.microbiol.china.150500 CrossRef Google Scholar
[26]	Yang PLS, Zhang Y, Wu G, Li J. 2021. Antibacterial activity of volatile oil from Jiugong Xiangju. The Food Industry 42:4 Google Scholar
[27]	Xiao Z, Fan B, Niu Y, Liu J, Ma S, et al. 2017. Analysis of the key aroma compounds of Chrysanthemum essential oils by GC-MS/GC-O coupled with PCA. Journal of Chinese Institute of Food Science and Technology 17:287−92 doi: 10.16429/j.1009-7848.2017.12.036 CrossRef Google Scholar
[28]	Cui H, Bai M, Sun Y, Abdel-Samie MAS, Lin L. 2018. Antibacterial activity and mechanism of Chuzhou chrysanthemum essential oil. Journal of Functional Foods 48:159−66 doi: 10.1016/j.jff.2018.07.021 CrossRef Google Scholar
[29]	Haouas D, Cioni PL, Ben Halima-Kamel M, Flamini G, Ben Hamouda MH. 2012. Chemical composition and bioactivities of three Chrysanthemum essential oils against Tribolium confusum (du Val) (Coleoptera: Tenebrionidae). Journal of Pest Science 85:367−79 doi: 10.1007/s10340-012-0420-7 CrossRef Google Scholar
[30]	Tawaha K, Hudaib M. 2010. Volatile oil profiles of the aerial parts of Jordanian garland, Chrysanthemum coronarium. Pharmaceutical Biology 48:1108 doi: 10.3109/13880200903505641 CrossRef Google Scholar
[31]	Peana AT, Moretti M. 2008. Linalool in Essential Plant Oils: Pharmacological Effects. In Botanical Medicine in Clinical Practice, eds. Watson RR, Preedy VR. Wallingford, UK: CABI. pp. 716−24 https://doi.org/10.1079/9781845934132.0716
[32]	Abd El-Baky RM, Hashem ZS. 2016. Eugenol and linalool: Comparison of their antibacterial and antifungal activities. African Journal of Microbiology Research 10:1860−72 doi: 10.5897/ajmr2016.8283 CrossRef Google Scholar
[33]	Knöppel H, Schauenburg H. 1989. Screening of household products for the emission of volatile organic compounds. Environment International 15:413−18 doi: 10.1016/0160-4120(89)90056-1 CrossRef Google Scholar
[34]	Özek T, Tabanca N, Demirci F, Wedge DE, Başer KHC. 2010. Enantiomeric distribution of some linalool containing essential oils and their biological activities. Records of Natural Products 4:180−92 Google Scholar
[35]	De-Oliveira ACAX, Ribeiro-Pinto LF, Paumgartten FJR. 1997. In vitro inhibition of CYP2B1 monooxygenase by β-myrcene and other monoterpenoid compounds. Toxicology Letters 92:39−46 doi: 10.1016/S0378-4274(97)00034-9 CrossRef Google Scholar
[36]	Yin C, Liu B, Wang P, Li X, Li Y, et al. 2020. Eucalyptol alleviates inflammation and pain responses in a mouse model of gout arthritis. British Journal of Pharmacology 177:2042−57 doi: 10.1111/bph.14967 CrossRef Google Scholar
[37]	Betts TJ. 2001. Chemical characterisation of the different types of volatile oil constituents by various solute retention ratios with the use of conventional and novel commercial gas chromatographic stationary phases. Journal of Chromatography A 936:33−46 doi: 10.1016/S0021-9673(01)01284-5 CrossRef Google Scholar
[38]	Brasesco C, Gende L, Negri P, Szawarski N, Iglesias A, et al. 2017. Assessing in vitro acaricidal effect and joint action of a binary mixture between essential oil compounds (Thymol, Phellandrene, Eucalyptol, Cinnamaldehyde, Myrcene, Carvacrol) over Ectoparasitic Mite Varroa destructor (Acari: Varroidae). Journal of Apicultural Science 61:203−15 doi: 10.1515/jas-2017-0008 CrossRef Google Scholar
[39]	Qin R, Liang Z, Li G, Zhou L, Chen H. 2017. Research progress on chemical reaction of sesquiterpene of heavy turpentine. Chinese Journal of Tropical Agriculture 37:84−87 Google Scholar
[40]	Qiao Y, Xie B, Zhang Y, Zhou H, Pan S. 2007. Study on Aroma Components in Fruit From Three Different Satsuma Mandarin Varieties. Agricultural Sciences in China 6:1487−93 doi: 10.1016/S1671-2927(08)60012-7 CrossRef Google Scholar

About this article

Cite this article

Liu H, Chen X, Chen H, Guo S, Huang C, et al. 2022. Detection and analysis of the volatile components in the essential oils of Chrysanthemum and Opisthopappus species and their hybrid progeny. Ornamental Plant Research 2:7 doi: 10.48130/OPR-2022-0007

Liu H, Chen X, Chen H, Guo S, Huang C, et al. 2022. Detection and analysis of the volatile components in the essential oils of Chrysanthemum and Opisthopappus species and their hybrid progeny. Ornamental Plant Research 2:7 doi: 10.48130/OPR-2022-0007

Figures(6) / Tables(1)

Download PDF

Article Metrics

Article views(4535) PDF downloads(820)

Other Articles By Authors

on this site
on Google Scholar

HTML

INTRODUCTION

Chrysanthemums are perennial floral species in the family Compositae^[1]. They produce economically valuable ornamental flowers with multiple uses (e.g., as medicine, food, and tea)^[2]. Opisthopappus Shih is a genus endemic to China and distributed in the Taihang Mountains. Opisthopappus taihangensis and Opisthopappus longilobus, which are the two species in this genus, are second-class, critically endangered, and protected plants in China^[3]. Both species are resistant to drought, shade, and cold stresses. Their flowers are mostly white, making them an important germplasm resource with ecological, ornamental, and economic value^[4−7].

To date, research on Opisthopappus plants has mainly focused on the genetic differences and interrelationships among O. taihangensis varieties^[8], the physiological characteristics underlying drought resistance and transcriptome changes^[9,10], genetic diversity^[11], tissue culture^[3,12,13], metal element contents in the soil in which O. longilobus is grown^[11], and hybrid breeding involving Opisthopappus plants and related species^[14]. However, the fragrance and essential oil components of O. taihangensis and O. longilobus flowers have not been comprehensively identified and characterized. Therefore, the objective of this study was to detect and analyze the fragrance and essential oil components of Opisthopappus flowers, with a particular focus on their antibacterial properties, which may be relevant for increasing the economic value of Opisthopappus species. The findings of this study may provide researchers and breeders with important information related to the protection, development, and utility of endangered Opisthopappus plants.

The commonly used methods for extracting essential oils include steam distillation, solvent extraction (including supercritical CO₂ extraction), and the application of high pressure. Characteristic aromatic and volatile oils have been extracted from flowers, leaves, fruits, stems, and other plant parts. The main volatile components in essential oils are terpenes. The terpenoids of essential oils are primarily monoterpenes and sesquiterpenes. In addition to olefin, essential oils also contain alcohols, aldehydes, ketones, esters, and other naturally occurring terpenoids. The essential oils extracted from aromatic plants are an extremely important raw material in the fragrance industry and are widely exploited in the daily-use chemical industry. Essential oils are also used for the production of food and medicine because of their diverse biological activities^[15,16]. The essential oils of chrysanthemum have various uses in many fields (e.g., to enhance the storage of vegetables and meat and food preservation). Unlike pesticides and other harmful compounds, chrysanthemum essential oils are natural and safe for human consumption. Moreover, they have antibacterial and antioxidant properties as well as proven pharmacological effects that can prevent infections^[17−19], eliminate inflammation, and remove scars. Therefore, these essential oils have been used in cosmetics and for massage therapy^[20]. The compounds in aromatic essential oils with the strongest antibacterial effects are mainly terpenes, phenols, and alcohols, which are commonly produced by aromatic plants^[21]. Previous research revealed that aromatic plant essential oils inhibit the activities of pathogenic bacteria by altering the fatty acid outer membrane, degrading the cell membrane, and inducing the leakage of metabolites and ions^[22]. Chrysanthemum indicum essential oils can be included in moisturizing creams, mosquito repellents, laundry detergents, dishwashing liquids, shower gels, and shampoos to provide these daily-use products with the fragrance and antibacterial and anti-inflammatory properties of C. indicum^[23]. The predominant volatile aromatic components of the Chrysanthemum morifolium 'Tianmeng Mountain Imperial' essential oil include 22 types of hydrocarbons, 9 types of alcohols, 7 types of esters, and 2 types of ketones^[24]. Researchers used a water distillation method to extract the essential oils of C. morifolium 'Kunlun Snow' plants. A micro-dilution method used to investigate the inhibitory effect of the C. morifolium 'Kunlun Snow' essential oil on cryptococcus fungi revealed that the essential oil treatment can degrade the fungal cell membrane and alter cell membrane permeability^[25]. Other researchers extracted essential oils from C. morifolium 'Jiugongxiangju' stems and leaves via water distillation. The essential oils were analyzed by gas chromatography–mass spectrometry (GC-MS) and tested for their antibacterial properties. These analyses confirmed that C. morifolium 'Jiugongxiangju' essential oils have antibacterial effects^[26]. Earlier research that applied GC-MS and GC-olfactometry techniques to identify the aromatic components in seven chrysanthemum essential oils revealed terpenes, esters, alcohols, ketones, acids, and aldehydes as the primary compounds^[27]. Moreover, the antibacterial activities of the C. morifolium 'Chuju' essential oil and the underlying mechanism were determined on the basis of an SDS-PAGE analysis, an examination of DNA topoisomerase activity, and an oxidative respiration metabolism test. The results of the DNA topoisomerase analysis demonstrated that the C. morifolium 'Chuju' essential oil simultaneously inhibits the activities of topoisomerases I and II^[28]. A previous investigation analyzed the essential oil components of three Chrysanthemum species (C. coronarium, C. fuscatum, and C. grandiflorum) by GC-MS, which revealed the insecticidal activities of the essential oils. Furthermore, essential oils extracted from various chrysanthemum species according to diverse methods can protect crops from pest infestations, with implications for small-scale grain production^[29].

On the basis of the available wild resource collection and the findings of our earlier hybridization research, we selected Chrysanthemum and Opisthopappus wild species, varieties, and hybrid offspring for this study. Essential oils were extracted from C. 'xiangjin', C. 'xiangyun', C. 'xinjiboju', O. taihangensis, O. longilobus, C. lavandulifolium, and C. 'minghuangju' and their compositions were analyzed. Specifically, HS-SPME-GC-MS technology was used to identify the volatile components of the extracted essential oils and to analyze the types of compounds and the components unique to particular plants. The results of this study may be relevant for characterizing chrysanthemum essential oil components with important industrial uses.

DISCUSSION

The most common chrysanthemum essential oil is yellow or green, In this study, the C. 'xiangyun' and C. 'minghuangju' essential oils were extracted at a relatively high rate and had a special color. Essential oils vary significantly in terms of color because of the diversity in their phytochemical components (e.g., ochre red myrrh essential oil, red orange essential oil with blue–purple fluorescence under high-intensity light, blue chamomile essential oil, black vetiver essential oil, and light green fragrant bergamot essential oil). The essential oil of Matricaria recutita, which belongs to the family Compositae, is similar to the C. 'xiangyun' and C. 'minghuangju' essential oils extracted in this study, both of which were blue. The chamomile essential oil is blue because of the presence of the organic compound azulene. The chamomile plant itself does not contain azulene, but it does contain a matricin. The matricin is the result of a series of chemical reactions (e.g., dehydration, hydrolysis, and decarboxylation) during the extraction process. The matricin are responsible for the blue coloration of the chamomile essential oil. Naturally obtained azulene may produce a variety of colors, including blue, green, blue–purple, or even red–purple. In addition to German chamomile, some yarrow plants also contain matricin. Thus, their essential oil also appears blue because of the presence of the azure hydrocarbon. Moreover, some mugwort plants, such as wormwood, also produce blue essential oils.

Regarding the essential oil odors, we revealed that the 225 compounds detected in seven essential oil samples included caryophyllene (trans-caryophyllene), o-cumene, γ-terpinene, (1S, 3R)-cis-4-carene, β-phellandrene, and α-phellandrene. The relatively abundant compounds included thymol, D-camphor, eucalyptol, borneol, linalool, syringone, (−)-α-cubic benzene, α-epoxy-terpineol acetate, pinene, β-phellandrene, 4-terpene alcohol, borneol acetate, beta-elemene, 3-decenoic acid, and linalool, of which pinene, D-camphor, and eucalyptol were the main essential oil constituents with a pleasant aroma as well as biological activities.

Among the identified compounds, the representative acyclic monoterpenes were myrcene, linalool, and phellandrene; the representative monocyclic monoterpenes were terpineol and terpinene; the representative bicyclic monoterpenes were pinene, camphene alkene, and camphor; and the representative sesquiterpenes were farnesol and caryophyllene. Small aliphatic compounds, including alcohols, aldehydes, ketones, and acids, were also frequently detected in the analyzed essential oils.

Among them, caryophyllene, camphor and other substances are generally the main volatile components of wild chrysanthemum, ground cover chrysanthemum and some wormwood plants^[29,30]. Both camphor and camphene have camphor-type aromas, so the odor of O. longilobus, C. 'xiangyun' and C. lavandulifolium essential oil with relatively high contents of camphor and camphene are relatively cool and slightly irritating. The highest relative content in O. longilobus essential oil is Eucalyptol. Eucalyptol is a monoterpenoid compound with a camphor-like odor.

Linalool, which was identified as a component of the Taihang chrysanthemum essential oil, produces an aroma that is similar to that of lily of the valley and is one of the most important compounds in the fragrance and flavor industries. Additionally, it decreases the pain responses mediated by various neurotransmitter systems^[31] and has antioxidant, anti-inflammatory, anticancer, antispasmodic, and antiparasitic activities^[32]. However, a previous study indicated that more than 95% of the linalool produced worldwide is used as an aromatizer and flavor enhancer^[33]. Plants with high linalool contents include oregano (90.3%), coriander (73.7%), salvia (70.6%), spinach (61.5%), basil (43.1%), prickly ash (46.1%), and marjoram (41.2%)^[34]. The total annual demand for L-linalool is 12,000 tons, but only 5,400 tons are produced worldwide under natural conditions.

Camphor, which was detected as the most abundant component in the C. 'xiangyun' essential oil, has a distinctive spicy aroma and taste, although its taste eventually dissipates. Moreover, camphor has a strong inhibitory effect on pests and bacteria. Specifically, it inhibits E. coli growth because of its detrimental effects on bacterial metabolism, chemotaxis, and anti-stress-related responses^[35].

Eucalyptol, which has the highest relative content in O. longilobus essential oil, is anti-inflammatory and analgesic, reducing pain and inflammation through mechanisms that may involve antioxidant effects^[36].

Beta-phellandrene is a common constituent of aromatic plant essential oils. It is a natural bioactive insecticide^[37]. Many bioinsecticides contain β-phellandrene as an important active ingredient^[38]. Caryophyllene is a bicyclic sesquiterpenoid that can be used to alter the flavor of foods containing clove, nutmeg, and citrus components^[39]. Furthermore, γ-terpinene and α-terpinene often coexist and are associated with citrus aromas^[40]. Phellandrene is a spice intermediate that is also associated with citrus aromas. It is commonly used as a natural active ingredient in biopesticides. It can also be used as a synthetic raw material for the production of terpene resins and menthol. The antibacterial, antiseptic, and insecticidal components of chrysanthemum essential oils, including β-thumberene, β-phellandrene, and other volatile compounds, are irritating to the skin. Thus, chrysanthemum essential oils should be diluted with other essential oils before they are used.

Essential oils produced by aromatic plants have a variety of functions. For example, most of the compounds that are responsible for the volatilized odors of essential oils also have strong antibacterial effects. Furthermore, in addition to inhibiting the growth of bacteria and fungi, the volatile compounds in essential oils can attract insect pollinators, prevent pest infestations, and inhibit the growth of other plants (i.e., allelopathic effect). As pure natural bacteriostatic agents, plant essential oils leave minimal residues and are volatile, highly degradable, and relatively non-toxic (i.e., environmentally friendly), which is in sharp contrast to many synthetic pesticides and insecticides. Therefore, they have been included in horticultural products, food, medicine, and beauty products. They are also currently the focus of considerable research and development across industries. In this study, we extracted chrysanthemum essential oils and verified their antibacterial effects.

Essential oil type name	Bacteriostatic ring width (mm)			The average value (mm)
C. 'xiangjin' essential oil	3.25	2.25	3	2.8 ± 0.55
C. 'xiangyun' essential oil	10	4.25	8	7.42 ± 3.17
C. 'xinjiboju' essential oil	3.25	4.25	11	6.17 ± 4.84
O. taihangensis essential oil	3.45	14	15	11.15 ± 7.7
O. longilobus essential oil	2.35	2.15	2	2.17 ± 0.18
C. 'minghuangju' essential oil	2.55	2.25	3	2.6 ± 0.4
C. lavandulifolium essential oil	4.25	3.75	4.50	4.17 ± 0.52

{{lists.name}}

Detection and analysis of the volatile components in the essential oils of Chrysanthemum and Opisthopappus species and their hybrid progeny