Chemical variability of peel and leaf essential oils of 15 species of mandarins

Peel and leaf oils of 58 mandarin cultivars, belonging to 15 different species were obtained from fruits and leaves collected on mandarin-trees submitted to the same pedoclimatic and cultural conditions. Their chemical composition was investigated by capillary GC, GC/MS and 13C NMR and the results were submitted to a cluster analysis and a discriminant analysis. Three major chemotypes, limonene, limonene/gamma-terpinene and linalyl acetate/limonene, were distinguished for peel oils while three other chemotypes, sabinene/linalool, gamma-terpinene/linalool and methyl N-methylanthranilate, were observed for leaf oils.     

The Chemical Constituents of the Essential Oil from the Flowers,Leaves and Peels of Citrus aurantium

Citrus aurantium L. var. amara Engl., is a better species of sour oranges. There are essential oils in the flowers, the peels, the leaves and the branches of C. aurantium. The flower oil can be used in the preparation of perfumes of high quality. The peel oil is used mainly for the flavor-endowing of soft drinks, alcoholic drinks, bread, confectionaries and cakes. In order to control the quality of the essential oils and to improve them, we have systema- tically studied the chemical constituents of the flowers, the leaves and the peals of C. aurantium with our preparation. 12 main components were separated by silica gel column chromatography. The following 33 chemical components were identified by IR, GC-MS and GC retention index: α-thujene, α-pinene, camphene, β-pinene, myrcene, limonene, β-ocimene, trans-linalooloxide (furanoid), cis-linalooloxide (furanoid), linalool, 1,4-p-methadien-7-ol, trans-pinocarveol, camphor, terpinen-4-ol α-terpineol, nerol, citral-b, geraniol, linalylacetate, citrala, trans-linalooloxide (pyranoid), methyl anthranilate, terpinyl acetate, cis-linalooloxide (pyranoid), neryl acetate. geranyl acetate, nonanal, β-caryophyllene, α-humulene, γ-muurolene, β-nerolidol, farnesol, α- nerolidol. GC retention index of 33 compounds were measured. A fast method for routine determination is presented.     

Studies on Leaf Oils of Citrus Species

Leaf oil samples of four Japanese citrus species were analysed by gas chromatography to determine the detailed composition of each leaf oil. The following components were identified: α-pinene, α-thujene, camphene, β-pinene, sabinene, β-myrcene, α-terpinene, limonene, β-phellandrene, trans-2-hexen-1-al, γ-terpinene, p-cymene, terpinolene, cis-2-penten-1-ol, n-hexyl alcohol, cis-3-hexen-1-ol, trans-2-hexen-1-ol, p-α-dimethylstyrene linalool, linalyl acetate, β-elemene, terpinen-4-ol, caryophyllene, humulene, α-terpineol, neryl acetate, geranyl acetate, β-selinene, geraniol and thymol. Most components were contained in common in leaf oils of the four citrus species, but relative contents of some of the components; such as γ-terpinene, linalyl acetate, and thymol differed from species to species. For example, γ-terpinene was the major component (33.8%) of Hassaku, whereas it was only a minor component in Daidai. Daidai is characterized by a very high content of linalyl acetate (35%) which is only a trace in the other three species. Kishu-mikan is characterized by a high content of thymol (15%).     

Anti-inflammatory activity of linalool and linalyl acetate constituents of essential oils

Linalool and linalyl acetate are the principal components of many essential oils known to possess several biological activities, attributable to these monoterpene compounds. In this work, we evaluated individually the anti-inflammatory properties of (-) linalool, that is, the natural occurring enantiomer, and its racemate form, present in various amounts in distilled or extracted essential oils. Because in the linalool-containing essential oils, linalyl acetate, is frequently present, we also examined the anti-inflammatory action of this monoterpene ester. Carrageenin-induced edema in rats was used as a model of inflammation. The experimental data indicate that both the pure enantiomer and its racemate induced, after systemic administration, a reduction of edema. Moreover, the pure enantiomer, at a dose of 25 mg/kg, elicited a delayed and more prolonged effect, while the racemate form induced a significant reduction of the edema only one hour after carrageenin administration. At higher doses, no differences were observed between the (-) enantiomer and the racemate; a further increase in the dose of both forms did not result in an increased effect at any time of observation. The effects of equi-molar doses of linalyl acetate on local edema were less relevant and more delayed than that of the corresponding alcohol. These finding suggest a typical pro-drug behavior of linalyl acetate. The results obtained indicate that linalool and the corresponding acetate play a major role in the anti-inflammatory activity displayed by the essential oils containing them, and provide further evidence suggesting that linalool and linalyl acetate-producing species are potentially anti-inflammatory agents.     

The effect of lemon, orange and bergamot essential oils and their components on the survival of Campylobacter jejuni, Escherichia coli O157, Listeria monocytogenes, Bacillus cereus and Staphylococcus aureus in vitro and in food systems

AIMS: To investigate the effectiveness of oils and vapours of lemon (Citrus limon), sweet orange (Citrus sinensis) and bergamot (Citrus bergamia) and their components against a number of common foodborne pathogens. METHODS AND RESULTS: The disc diffusion method was used to screen the oils and vapours against Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, Escherichia coli O157 and Campylobacter jejuni. The survival of each species, demonstrated to be susceptible in the in vitro studies, was tested on cabbage leaf for 60 s by direct contact and on chicken skin for 10 min by direct contact and 24 h by vapour. The results indicate that bergamot was the most inhibitory essential oil (EO) and citral and linalool mimicked its effect (P > 0.001). Citral and linalool vapours produced 6 log reductions in L. monocytogenes, Staph. aureus and B. cereus populations on cabbage leaf after 8-10 h exposure but bergamot vapour exposure, while producing a similar reduction in L. monocytogenes and B. cereus populations, had no effect on Staph. aureus. CONCLUSIONS: Bergamot was the most effective of the oils tested and linalool the most effective anti-bacterial component. Gram-positive bacteria were more susceptible than Gram-negative bacteria in vitro, although Camp. jejuni and E. coli O157 were inhibited by bergamot and linalool oils and by linalool vapour. All bacteria tested were less susceptible in food systems than in vitro. Of the Gram-positive bacteria tested Staph. aureus was the least susceptible to both the oils and the components tested. SIGNIFICANCE AND IMPACT OF THE STUDY: Results suggest the possibility that citrus EOs, particularly bergamot, could be used as a way of combating the growth of common causes of food poisoning.     

苦橙叶精油化学成分及抗炎作用研究

为探究苦橙叶精油的抗炎作用。实验采用气相-质谱联用法(GC-MS)分析精油成分,并建立脂多糖(LPS)诱导RAW 264.7细胞炎症模型,用Griess法检测一氧化氮(NO)含量评价其体外抗炎作用,随后进一步通过巴豆油致小鼠耳肿胀模型和鸡蛋清致小鼠足肿胀模型评价其体内抗炎作用。结果表明苦橙叶精油成分以酯类、醇类物质为主;25μg/mL浓度能显著抑制RAW 264.7细胞NO的释放;中浓度苦橙叶精油能明显减轻小鼠耳肿胀程度;低、中、高浓度苦橙叶精油均对小鼠足肿胀模型有炎症缓解作用,并于肿胀前期呈浓度依赖性。以上实验证明苦橙叶精油在体外和体内具有一定抗炎作用。     

Inhibition of cholinesterase by essential oil from food plant

Inhibition of cholinesterase has attracted much attention recently because of its potential for the treatment of Alzheimer's disease. In this work, the anticholinesterase activities of plant oils were investigated using Ellman's colorimetric method. The results indicate that essential oils obtained from Melissa officinalis leaf and Citrus aurantifolia leaf showed high acetylcholinesterase and butyrylcholinesterase co-inhibitory activities. C. aurantifolia leaf oil revealed in this study has an IC(50) value on acetylcholinesterase and butyrylcholinesterase of 139 ± 35 and 42 ± 5 μg/ml, respectively. GC/MS analysis revealed that the major constituents of C. aurantifolia leaf oil are monoterpenoids including limonene, l-camphor, citronellol, o-cymene and 1,8-cineole.     

Toxic effects of six plant oils alone and in combination with controlled atmosphere on Liposcelis bostrychophila (Psocoptera: Liposcelididae).

Six plant essential oils alone as repellent and fumigant, and in combination with the controlled atmosphere against Liposcelis bostrychophila Badonnel were assessed in the laboratory. These essential oils were extracted from the leaves of six source plants: Citrus tangerina Tanaka, Citrus aurantium L., Citrus bergamia Risso et Poiteau, Pinus sylvestris L., Cupressus funebris End]., and Eucalyptus citriodora Hook. The repellency test indicated that L. bostrychophila adults were repelled by filter paper strips treated with six essential oils. Of these essential oils, the C. funebris oil was most effective followed by that of F. sylvestris, C. tangerina, C. bergamia, and E. citriodora. The average repellency of the C. aurantium oil against L. bostrychophila adults was significantly lower than other five test oils by day 14. These essential oils had a high level of toxicity in the fumigation assay against L. bostrychophila adults at both 10 and 20 ppm. When combined with two controlled atmosphere treatments (12% CO2 + 9% O2, and 10% CO2 + 5% O2, balanced N2), the toxicity of plant oils was enhanced significantly.     

Cytotoxicity of lavender oil and its major components to human skin cells

Abstract.  Lavender ( Lavandula angustifolia ) oil, chiefly composed of linalyl acetate (51%) and linalool (35%), is considered to be one of the mildest of known plant essential oils and has a history in wound healing. Concerns are building about the potential for irritant or allergenic skin reactions with the use of lavender oil. This study has demonstrated that lavender oil is cytotoxic to human skin cells in vitro (endothelial cells and fibroblasts) at a concentration of 0.25% (v/v) in all cell types tested (HMEC-1, HNDF and 153BR). The major components of the oil, linalyl acetate and linalool, were also assayed under similar conditions for their cytotoxicity. The activity of linalool reflected that of the whole oil, indicating that linalool may be the active component of lavender oil. Linalyl acetate cytotoxicity was higher than that of the oil itself, suggesting suppression of its activity by an unknown factor in the oil. Membrane damage is proposed as the possible mechanism of action.     

25个种和品种的柑桔果皮精油的化学成分

用双柱毛细管气相色谱保留时间法和GC-MS法分析了25个种和品种的柑桔果皮精油的化学成分,共鉴定出精油化学成分61个。所有精油的主要成分都是柠檬烯。依据精油中柠檬烯含量的不同,将被分析的25个植物种和品种分成三组:枸橼、柠檬类为一组,精油中柠檬烯含量为50％～70％;酸橙、甜橙和柚类为一组,精油中柠檬烯的含量大于92％;宽皮柑桔类为一组,精油中柠檬烯的含量为70％～90％(少数种达94.18％)。这一实验结果与近来有关栽培柑桔只有枸橼、柚和宽皮柑桔具有生物学种的价值的看法相类似。     

Antimicrobial activity of six constituents of essential oil from Salvia

The antimicrobial activity of three Salvia species, i.e. S. santolinifolia, S. hydrangea and S. mirzayanii, essential oils were investigated. The essential oils were obtained from the aerial parts of plants and analyzed by GC-MS. The main constituents of aforementioned species were alpha-pinene (72.4%), beta-pinene (6.6%) and limonene (5.3%); beta-caryophyllene (25.1%), 1,8-cineol (15.2%) and caryophyllene oxide (11.5%); alpha-terpinenyl acetate (22.6%), 1,8-cineol (21.2%) and linalool (8.9%), respectively. Bioassays exhibited that the property of the oil of S. myrzayanii was superior to others. The antimicrobial activity of essential oil from Salvia species may well be due to the presence of synergy between six tested compounds (linalool, 1,8-cineol, alpha-pinene, beta-pinene, beta-caryophyllene and limonene) and other constituents of the oils with various degrees of antimicrobial activity. Among these, linalool and 1,8-cineol had the highest antimicrobial activity.     

In vitro effect of essential oils from Cinnamomum aromaticum,Citrus limon and Allium sativum on two intestinal flagellates of poultry,Tetratrichomonas gallinarum and Histomonas meleagridis

Essential oils may be effective preventive or curative treatments against several flagelated poultry parasites and may become primordial either to organic farms, or as more drugs are bannished. The anti-flagellate activity of essential oils obtained from fresh leaves of Cinnamomum aromaticum, Citrus limon pericarps and Allium sativum bulbs was investigated in vitro on Tetratrichomonas gallinarum and Histomonas meleagridis. On T. gallinarum, the minimal lethal concentration (MLC) at 24 hours was 0.25 microliter/ml for C. aromaticum oil, and 0.125 microliter/ml for C. limon and A. sativum oils. On H. meleagridis, MLC was 0.5 microliter/ml for C. aromaticum oil and 1 microliter/ml for C. limon and A. sativum oils at 24 and 48 hours. Moreover, no synergistic effects were evidenced in vitro. The essential oil constituents, based on their GC retention times have been also identified. The major component is trans-cinnamaldehyde (79%) for C. aromaticum; limonene for C. limon (71%) and diallyl tri- and disulfide (79%) for A. sativum. Even if concentration and protocol adaptations are required for successful in vivo treatments, it appears that these oils may be useful as chemotherapeutic agents against several poultry parasites.     

Toxicity of citrus essential oils against Ceratitis capitata (Diptera: Tephritidae) larvae

Citrus peel essential oils are considered to constitute the most important resistance factor of citrus fruits against fruit flies. Essential oils were obtained from three sweet orange varieties, one bitter orange and one lemon variety. Yield, chemical composition and toxicity against neonates of the Mediterranean fruit fly were determined. Based on chemical analysis, the toxicity of commercially purchased major and minor components (monoterpenes and sesquiterpenes) of essential oils was determined. In addition, fractions were prepared to evaluate the role of minor components in the toxicity of crude essential oils. Limonene was by far the most abundant ingredient (96.2–97.4%) in all sweet orange varieties and in bitter orange, while the concentration of limonene was much lower in lemon essential oils (74.3%). Orange and bitter orange essential oils were more toxic than lemon essential oils. The toxicity of orange and bitter orange essential oils was similar to that of their major component limonene. In tests of commercially purchased chemicals, the oxygenated components of essential oils were more toxic than hydrocarbons but their low concentration in citrus essential oils could not affect the toxic activity of essential oils. The presence of α-pinene and β-pinene seems to account for the lower toxicity of lemon essential oils in relation to other citrus essential oils. The importance of understanding the toxicity of essential oils in relation to their composition and their role regarding the resistance of citrus fruits to Ceratitis capitata infestation is discussed.     

Activity of essential oils and individual components against acetyl- and butyrylcholinesterase

We have tested acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of nineteen essential oils obtained from cultivated plants, namely one from Anethum graveolens L. (organic fertilizer), two from Foeniculum vulgare Mill. collected at fully-mature and flowering stages (organic fertilizer), two from Melissa officinalis L. (cultivated using organic and chemical fertilizers), two from Mentha piperita L. and M. spicata L. (organic fertilizer), two from Lavandula officinalis Chaix ex Villars (cultivated using organic and chemical fertilizers), two from Ocimum basilicum L. (green and purple-leaf varieties cultivated using only organic fertilizer), four from Origanum onites L., O. vulgare L., O. munitiflorum Hausskn., and O. majorana L. (cultivated using organic fertilizer), two from Salvia sclarea L. (organic and chemical fertilizers), one from S. officinalis L. (organic fertilizer), and one from Satureja cuneifolia Ten. (organic fertilizer) by a spectrophotometric method of Ellman using ELISA microplate-reader at 1 mg/ml concentration. In addition, a number of single components widely encountered in most of the essential oils [gamma-terpinene, 4-allyl anisole, (-)-carvone, dihydrocarvone, (-)-phencone, cuminyl alcohol, cumol, 4-isopropyl benzaldehyde, trans-anethole, camphene, iso-borneol, (-)-borneol, L-bornyl acetate, 2-decanol, 2-heptanol, methyl-heptanol, farnesol, nerol, iso-pulegol, 1,8-cineole, citral, citronellal, citronellol, geraniol, linalool, alpha-pinene, beta-pinene, piperitone, iso-menthone, menthofurane, linalyl oxide, linalyl ester, geranyl ester, carvacrol, thymol, menthol, vanilline, and eugenol] was also screened for the same activity in the same manner. Almost all of the essential oils showed a very high inhibitory activity (over 80%) against both enzymes, whereas the single components were not as active as the essential oils.     

Essential oil composition and variability of Thymus lotocephalus and Thymusxmourae

The composition of the essential oils of four populations of Thymus lotocephalus G. López and R. Morales and one population of T.xmourae Paiva and Salgueiro, two endemic taxa from Portugal, was investigated mainly by GC and GC-MS. Txmourae is a natural hybrid between T. lotocephalus and T. mastichina (L.) L. subsp. donyanae R. Morales, which essential oil was analysed for the first time. In its oil, it was possible to find compounds of both parents, which could enable us to confirm its intermediate status between those two taxa. 1,8-Cineole and borneol were the main constituents in the essential oil of T.xmourae, whereas linalool, geranyl acetate and 1,8-cineol were the major ones in T. lotocephalus. Intermedeol was also an important constituent in the oils of both taxa. Nevertheless, the volatile oils of the four populations investigated of T. lotocephalus showed important differences among the main constituents. In order to study their infraspecific variability, the results obtained in the analysis of individual plants were submitted to a Principal Component and Chemometric Cluster Analyses. Five types of essential oils were found: linalool, 1,8-cineole, linalool/1,8-cineole, linalyl acetate/linalool and geranyl acetate.     

柑桔提取物中主要成分的杀螨活性评价

【目的】研究柑桔提取物中主要杀螨活性成分,为柑桔提取物作为杀螨剂的使用奠定基础。【方法】采用乙醇、丙酮、乙酸乙酯、石油醚4种溶剂对北碚447的果皮与种子进行平行提取,对4种提取物进行杀螨活性评价。对北碚447的果皮乙醇提取物和乙酸乙酯提取物进行GC-MS分析,就其中主要成分进行杀螨活性评价,确定主要杀螨活性成分。【结果】发现柑桔乙醇提取物的杀螨活性最高;果皮提取物的杀螨活性高于种子;果皮和种子乙醇和乙酸乙酯提取物通过GC-MS分析共鉴定出35种成分,其中柠檬烯含量最高,和柠檬醛、4-松油醇、芳樟醇占提取物含量的85%以上;柠檬烯杀螨活性高于柠檬醛、松油醇、芳樟醇、?-蒎烯。【结论】柑桔提取物中主要的杀螨成分是柠檬烯、柠檬醛、4-松油醇、芳樟醇、?-蒎烯,以这些物质为主要有效成分的柑桔提取物类杀螨剂的研发具有重大意义。     

Studies on Leaf Oils of Citrus Species

Leaf oils from 6 domestic citrus species were analysed by gas chromatography and 32 compounds were identified as constituents of one or more oils. Most components present were common to all 6 citrus leaf oils, but the percent composition of some components, i.e. β-pinene, limonene, β-phellandrene, γ-terpinene, p-cymene, p-α-dimethylstyrene, citronellal, linalool and thymol methyl ether, differed considerably from species to species. For example, γ-terpinene is a main component (36.5%) of Shiikuwasha (Citrus depressa Hayata), but is a trace in leaf oils from Kawabata-mikan (C. aurea Tanaka) and Otaheite-orange (C. limonia Osbeck var. otaitensis Tanaka). Yuzu (C. Junos Sieb. ex Tanaka) is characterized by relatively high contents of β-phellandrene (11.2%) and p-α-dimethylstyrene (6.7%), which are minor constituents in the other 5 citrus leaf oils. Otaheite-orange is characterized by high contents of limonene (39.7%) and citronellal (10.0%).     

Diversity of essential oil glands of clary sage (Salvia sclarea L., Lamiaceae)

The Lamiaceae is rich in aromatic plant species. Most of these species produce and store essential oils in specialised epidermal oil glands, which are responsible for their specific flavour. Two types of glands producing essential oil and possessing different morphological structure can be found in Salvia sclarea : peltate and capitate glands. The content of single oil glands from different positions on the plant (corolla, calyx and leaf) were sampled using an SPME fibre and analysed by gas chromatography in order to study variability of the essential oil composition. It was found that the composition of terpenoids is quite variable within an individual plant. Capitate oil glands mainly produce three essential oil compounds: the monoterpenes linalool and linalyl acetate, and the diterpene sclareol. Peltate oil glands, however, accumulate noticeable concentrations of sesquiterpenes and an unknown compound (m/z = 354). Furthermore, the oil composition varies within each gland type according to the plant organ. Linalool and linalyl acetate are characteristic substances of flowers, whereas the sesquiterpenes occur in higher proportions in leaves. Even within one gland type on a single leaf, the chemical variability is exceedingly high.     

Antimicrobial activity of essential oils isolated from Portuguese endemic species of Thymus

AIMS: Thymus species are wild species mostly found in the arid lands of Portugal. Possible antimicrobial properties of Thymus essential oils have been investigated. The chemical composition of the essential oils and the antimicrobial activity of Thymus mastichina (L) L. subsp. mastichina, T. camphoratus and T. lotocephalus from different regions of Portugal were analysed. METHODS AND RESULTS: Hydrodistillation was used to isolate the essential oils and the chemical analyses were performed by gas chromatography (GC) and GC coupled to mass spectrometry. The antimicrobial activity was tested by the disc agar diffusion technique against Candida albicans, Escherichia coli, Listeria monocytogenes, Proteus mirabilis, Salmonella spp. and Staphylococcus aureus. Pure linalool, 1,8-cineole and a mixture (1 : 1) of these compounds were included. Linalool, 1,8-cineole or linalool/1,8-cineole and linalool/1,8-cineole/linalyl acetate were the major components of the essential oils, depending on the species or sampling place. The essential oils isolated from the Thymus species studied demonstrated antimicrobial activity but the micro-organisms tested had significantly different sensitivities. CONCLUSIONS: The antimicrobial activity of essential oils may be related to more than one component. SIGNIFICANCE AND IMPACT OF THE STUDY: Portuguese endemic species of Thymus can be used for essential oil production for food spoilage control, cosmetics and pharmaceutical use. Further studies will be required to elucidate the cell targets of the essential oil components.