Isotope ratio analysis by HRGC-MS of monoterpene hydrocarbons from citrus essential oils

The isotope ratio of monoterpene hydrocarbons in citrus essential oils of different origins was measured by ordinary high-resolution gas chromatography-mass spectrometry (HRGC-MS). The isotope ratio (Ir) was determined by the ratio of the isotope peak intensity (m/z 137) to the molecular mass peak intensity (m/z 136) of the monoterpene hydrocarbons. The accuracy of Ir was examined by measuring monoterpene hydrocarbon standards and 13C-labeled compounds. The isotope fingerprints based on the values of monoterpene hydrocarbons from lemon, lime and yuzu essential oils were determined. These citrus essential oils were also discriminated by a principal component analysis of their Ir data. The characteristic vectors showed that alpha-terpinene, beta-pinene and beta-phellandrene were important components for distinguishing between the citrus species. It is suggested that this technique will be applicable to evaluate the quality, genuineness and origin of citrus fruits and their products.     

Characterization by GC-MS of Vietnamese citrus species and hybrids based on the isotope ratio of monoterpene hydrocarbons

The isotope ratio of monoterpene hydrocarbons was used to characterize the citrus essential oils from different species and hybrids. Citrus cold-pressed peel oils from Vietnam were analyzed for the composition and isotope ratio of monoterpene hydrocarbons by using gas chromatography-mass spectrometry. A profile of citrus essential oils on the basis of their isotope ratio values and levels of monoterpene hydrocarbons was developed for Vietnamese citrus. The molecular isotope ratios were lower than those calculated from natural abundance of 13C and 2H. In addition, the isotope ratio of the base peaks (m/z 94/93) was significantly different among the citrus essential oils from different species and hybrids. The results would be applicable for the characterization of citrus essential oils from different origins.     

Isotope ratio by HRGC-MS of citrus Junos tanaka (yuzu) essential oils: m/z 137/136 of terpene hydrocarbons

The isotope ratios of monoterpene hydrocarbons in Citrus junos Tanaka (yuzu) essential oils from different origins were determined by ordinary high-resolution gas chromatography-mass spectrometry (HRGC-MS). Both intensities of the molecular mass peaks (m/z 136) and of the isotope peaks (m/z 137) of monoterpene hydrocarbons were measured by single-ion monitoring with an MS analysis. The isotope ratios (m/z 137/136) of the ten monoterpene hydrocarbons commonly contained in citrus essential oils, alpha-pinene, beta-pinene, sabinene, myrcene, alpha-phellandrene, alpha-terpinene, limonene, gamma-terpinene, beta-phellandrene and terpinolene, were determined in yuzu samples of the highest commercial quality from 42 different production districts. Statistical treatment of these data by the t-test and sign test revealed significant differences of the isotope effects in each yuzu sample. It is suggested that this technique will be applicable for evaluating the quality, genuineness and origin of citrus fruits and their products. The isotope fingerprints were also demonstrated in several citrus fruits other than the yuzu samples.     

Isotope Ratio by HRGC-MS of Citrus junos Tanaka (Yuzu) Essential Oils: m/z 137/136 of Terpene Hydrocarbons

The isotope ratios of monoterpene hydrocarbons in Citrus junos Tanaka (yuzu) essential oils from different origins were determined by ordinary high-resolution gas chromatography-mass spectrometry (HRGC-MS). Both intensities of the molecular mass peaks (m/z 136) and of the isotope peaks (m/z 137) of monoterpene hydrocarbons were measured by single-ion monitoring with an MS analysis. The isotope ratios (m/z 137/136) of the ten monoterpene hydrocarbons commonly contained in citrus essential oils, α-pinene, β-pinene, sabinene, myrcene, α-phellandrene, α-terpinene, limonene, γ-terpinene, β-phellandrene and terpinolene, were determined in yuzu samples of the highest commercial quality from 42 different production districts. Statistical treatment of these data by the t-test and sign test revealed significant differences of the isotope effects in each yuzu sample. It is suggested that this technique will be applicable for evaluating the quality, genuineness and origin of citrus fruits and their products. The isotope fingerprints were also demonstrated in several citrus fruits other than the yuzu samples.     

Phylogenetic relationships of the genus Chamaecyparis inferred from leaf essential oil

The species differentiation between Chamaecyparis formosensis, C. obtusa var. formosana, and C. obtusa, based on the composition of the leaf essential oils, was studied. The characterization of the oils by GC-FID and GC/MS analyses showed remarkable differences between these three essential oils. Cluster analysis (CA) and principal-component analysis (PCA) distinguished three groups of essential oils. The C. formosensis oil was dominated by α-pinene while those isolated from C. obtusa var. formosana and C. obtusa were characterized by high levels of (-)-thujopsene and α-terpinyl acetate, respectively. Moreover, the phylogenetic relationships of the genus Chamaecyparis were in agreement with previous findings based on morphological and molecular evidence. In addition, the essential oils from C. obtusa var. formosana could be classified into three chemical types, according to their different characteristic main compounds (β-elemol, (-)-thujopsene, and cis-thujopsenal). The biochemical correlations between the major constituents of the Chamaecyparis species were examined and their relationship is discussed.     

Determination of the volatile fraction of Polygonum bistorta L. at different growing stages and evaluation of its antimicrobial activity against two major honeybee (Apis mellifera) pathogens

The composition of the volatile fraction of Polygonum bistorta L. (also known as bistort or snakeroot) was investigated. Fresh aerial parts of this plant species were collected in the Western Italian Alps during the summer at three different phenological stages, namely vegetative, flowering, and fruiting, and steam-distilled in a Clevenger-type apparatus. The oils accounted for 0.004 to 0.010% of the fresh plant material, and their compositions were determined by GC/FID and GC/MS. The composition of the oils during the vegetative period varied both in quantity and quality; several classes of compounds were found with a predominance of alcohols in the vegetative phase, terpenes and linear-chained saturated hydrocarbons in the flowering phase, while saturated aliphatic acids and their methyl esters were predominant in fruiting phase. The most abundant compounds were 3-methylbut-3-en-1-ol in the vegetative phase, linalool in the flowering phase, and dodecanoic acid and its methyl ester in the fruiting phase. The obtained essential oils were then tested against two major bee pathogens, i.e., Paenibacillus larvae and Melissococcus plutonius, and against a reference bacterial species, Bacillus subtilis. Data were compared to those obtained with reference standards used against those pathogens such as the essential oils obtained from leaves and bark of Cinnamomum zeylanicum (cinnamon), and the antibiotic oxytetracyclin.     

槲寄生挥发性成分研究

目的：研究槲寄生挥发性成分。方法：利用水蒸汽蒸馏法提取槲寄生挥发性成分,用GC/MS进行分离测定,结合计算机检索技术对分离的化合物进行结构鉴定,应用色谱峰面积归一化法计算各成分的相对百分含量。结果：分离出119个成分,确定了66个化合物,占挥发油总量的77．31％。结论：槲寄生挥发性成分大于2％的化学成分有12种。     

Chemical composition and biological activities of essential oils extracted from Korean endemic citrus species

The aim of this study was to analyze the chemical composition of 14 kinds of citrus oils and to test their biological activities. Citrus essential oils were obtained by steam distillation from immature fruits collected from Jeju Island and were analyzed using gas chromatograph (GC)- flame ionization detectors (FID) and GC-MS. Limonene (55.4% to 91.7%), myrcene (2.1% to 32.1%), alpha-pinene (0.6% to 1.6%) and linalool (0.4% to 6.9%) were the major components in most citrus species. To evaluate in vitro antibacterial activity, all essential oils were tested against Propionibacterium acnes and Staphylococcus epidermidis. Nine out of fourteen citrus oils exhibited antibacterial activity against P. acnes, but not against S. epidermidis. The effects of the citrus oils on DPPH radical scavenging, superoxide radical anion scavenging, nitric oxide radical, and cytotoxicity were also assessed. Three essential citrus oils, Joadeung, Dongjunggyul, and Bujiwha, exhibited potent inhibitory effects on nitric oxide production. Two essential oils, Dongjunggyul and Joadeung, showed potent free radical scavenging activities in the DPPH assay. For future applications in cosmetic products, we also performed MTT assays in a human dermal fibroblast cell line. The majority of the essential oils showed no cytotoxicity. The results indicate that citrus essential oils can be useful natural agents for cosmetic application.     

In-vitro antimicrobial activity and chemical composition of Sardinian Thymus essential oils

Essential oils and their components are becoming increasingly popular as naturally occurring antimicrobial agents. In this work the chemical composition and the antimicrobial properties of Thymus essential oils and of their main components were determined. Three essential oils obtained from different species of Thymus growing wild in Sardinia and a commercial sample of Thymus capitatus oil were analysed. The essential oil components were identified by GC/MS analysis. The antimicrobial activity of the oils and components was determined against a panel of standard reference strains and multiple strains of food-derived spoilage and pathogenic bacteria, using a broth microdilution method. The GC/MS analysis showed that the major constituents of the oils were monoterpene hydrocarbons and phenolic monoterpenes, but the concentration of these compounds varied greatly among the oils examined. The results of the antimicrobial assay showed that essential oils extracted from Sardinian Thymus species have an antimicrobial activity comparable to the one observed in other thyme oils. It seems also confirmed that the antimicrobial properties of thyme essential oils are mainly related to their high phenolic content. Among the single compounds tested carvacrol and thymol turned out to be the most efficient against both reference strains and food-derived bacteria. The results of this study confirmed the possibility of using thyme essential oils or some of their components in food systems to prevent the growth of foodborne bacteria and extend the shelf-life of processed foods.     

石香薷挥发油提取的比较研究

利用GC-MS对石香薷挥发油进行了定性、定量分析。采取超临界CO2萃取、水蒸气蒸馏和有机溶剂石油醚萃取这三种方法提取石香薷挥发油。这三种方法提取石香薷挥发油的主要成分基本相似,主要为含氧化合物(香薷酮、百里香酚和香荆芥酚)等,采取超临界CO2萃取和水蒸气蒸馏的石香薷挥发油品质较优。超临界CO2萃取法为提取石香薷挥发油的理想方法。     

Chemical composition of essential oils from leaves of Helicteres guazumifolia (Sterculiaceae), Piper tuberculatum (Piperaceae), Scoparia dulcis (Arecaceae) and Solanum subinerme (Solanaceae) from Sucre, Venezuela

Essential oils, biosynthesized and accumulated in aromatic plants, have a wide range of applications in the pharmaceutical health, cosmetics, food and agricultural industry. This study aimed to analyze the secondary metabolites in some plant species in order to contribute to their chemotaxonomy. Leaves from Helicteres guazumifolia, Piper tuberculatum, Scoparia dulcis and Solanum subinerme were collected and their essential oils were obtained by means of hydro-distillation. The oil fraction was analyzed and identified by GC/MS. The extraction yields were of 0.004, 0.032, 0.016 and 0.005%, and the oil constituents of 88.00, 89.80, 87.50 and 89.47%, respectively. The principal oils found were: non-terpenoids volatile secondary metabolites (30.28%) in H. guazumifolia; sesquiterpenoids (20.82 and 26.09%) and oxigen derivated (52.19 and 25.18%) in P. tuberculatum and S. dulcis; and oxigen diterpenoids (39.67%) in S. subinerme. The diisobuthylphtalate (13.11%) in H. guazumifolia, (-)-spathulenol (11.37%) in P. tuberculatum and trans-phytol (8.29 and 36.00%) in S. dulcis and S. subinerme, were the principal constituents in their respective essential oils. The diisooctylphtalate were the essential oil common to all species, but the volatile compounds such as trans-pinane, L-linalool, beta-ionone, isophytol, neophytadiene, trans-phytol, dibutylphtalate and methyl hexadecanoate, were only detected in three of these essences. This suggests that these plants may require similar secondary metabolites for their ecological interactions, possibly due to common environmental factors.     

Volatile constituents of Aristolochia argentina

The essential oils from leaves, aerial stems and underground organs of Aristolochia argentina Gris., a medicinal plant popularly known as "charrúa", were obtained by hydrodistillation and analyzed by GC and GC/MS. Forty-three components were identified in the oils. All parts of the plant afforded volatile oils characterized by high levels of argentilactone (57-89%) and the presence of undecatriene isomers (0.3-4.0%), these latter compounds providing the essential oils and extracts with an intense particular odor. Terpenes account for the remaining portion of the essential oils (5-29%). Bicyclogermacrene predominates in the aerial parts of the plant, whereas ishwarane is the main terpene of the subterranean organs. Argentilactone, a suspected carcinogenic compound, was also identified in a medicinal commercial tincture of A. argentina.     

A simple method to obtain essential oils from Salvia triloba L. and Laurus nobilis L. by using microwave-assisted hydrodistillation

A microwave-assisted hydrodistillation protocol was modified to extract essential oils from leaves of Salvia triloba L. and Laurus nobilis L. The essential oils of these plants are generally obtained by hydrodistillation or steam distillation. The volatile compounds obtained by microwave-assisted hydrodistillation and hydrodistillation methods were analyzed by GC and GC/MS. Both distillation methods and analytical results were compared. 1,8-Cineole (46.8-54.2%) was the main component in the leaf oils of both samples. Although the distillation was accomplished in a shorter time, oil yields and 1,8-cineole contents were slightly higher in the microwave-assisted hydrodistillation compared to usual hydrodistillation. Microwave-assisted hydrodistillation appears to be an effective method for the production of essential oils.     

Chemical Composition and in vitro Biological Activities of Essential Oils from Conchocarpus fontanesianus (A. St.‐Hil.) Kallunki & Pirani (Rutaceae)

This study aimed at assessing the chemical composition of the essential oils from leaves and fruits of Conchocarpus fontanesianus, an endemic Brazilian species of Rutaceae. The plant material was harvested from two regions of the Atlantic rainforest in the State of São Paulo. The volatile compounds in the essential oils were extracted by hydrodistillation (HD), and analyzed by GC/FID and GC/MS, allowing the quantification and identification of 54 components in total, which comprise about 97% of the total oil composition. From the leaves collected in Caraguatatuba and Juréia‐Itatins, the major volatile compounds identified were as follows: spathulenol (22.32% and 16.67%) and α‐cadinol (9.7% and 14.76%). However, β‐myrcene (34.56%), (+)‐epi‐bicyclosesquiphellandrene (8.71%), and bicyclogermacrene (5.80%) were dominant in the fruits collected only in Juréia‐Itatins. The in vitro biological activities were tested to evaluate the cytotoxic, antifungal, and antioxidant potential of essential oils from leaves and fruits.     

Enantioselective GC–MS analysis of volatile components from rosemary (Rosmarinus officinalis L.) essential oils and hydrosols

Essential oils and hydrosols were extracted from rosemary harvested in different seasons, and the chemical compositions of volatile components in the two fractions were analyzed by gas chromatography–mass spectrometry (GC–MS). Enantiomers of some volatile components were also analyzed by enantioselective GC–MS. Classification of aroma components based on chemical groups revealed that essential oils contained high levels of monoterpene hydrocarbons but hydrosols did not. Furthermore, the enantiomeric ratios within some volatile components were different from each other; for example, only the (S)-form was observed for limonene and the (R)-form was dominant for verbenone. These indicate the importance of determining the enantiomer composition of volatile components for investigating the physiological and psychological effects on humans. Overall, enantiomeric ratios were determined by volatile components, with no difference between essential oils and hydrosols or between seasons.     

Composition of volatile oils of Styrax (Styrax officinalis L.) leaves at different phenological stages

The volatile oil composition of Styrax officinalis L. leaves was investigated by GC and GC–MS during the phenological cycle of this species in a population growing wild in France. Whatever the analysed stage, yields were low 0.01–0.02%. (E)-2-hexenal, octanol and geraniol were the main constituents in all these volatile oils. The level of sesquiterpenoids was the highest at the vegetative stage. However, the chemical composition of leaf essential oil was relatively constant during the phenological stage of this tree and 58% of the identified compounds were common at all the analysed oils.     

Chemical composition and antimicrobial activity of Citrus essences on honeybee bacterial pathogen <Emphasis Type="Italic">Paenibacillus larvae</Emphasis>, the causal agent of American foulbrood

Antimicrobial properties and chemical composition of four citrus fruit essential oils to control Paenibacillus larvae, the causal agent of American foulbrood disease (AFB) were determined. This honeybee larvae disease occurs throughout the world and is found in many beekeeping areas of Argentina. Citrus fruit essential oils tested were those from grapefruit (Citrus paradisi), sweet orange (Citrus sinensis), mandarin (Citrus nobilis) and lemon (Citrus limon). The components of the essential oils were identified by SPME-GC/MS analysis. The antimicrobial activity of the oils against P. larvae were determined by the broth microdilution method. Two way ANOVA tests for minimum inhibitory concentrations (MICs) data and minimal bactericide concentrations (MBCs) data, indicated significant differences between the strains and the oils tested. The antimicrobial assays showed that the oil of C. paradisi inhibited the bacterial strains at the lowest concentrations tested, MICs and MBCs averages of 385.0 mg/l and 770.0 mg/l, respectively. This property could be attributed to the kind and percentage of the volatile components of the oil, like limonene (69.9%) and myrcene (9.6%). The use of essential oils or their specific volatile components individually against pests related to food provision may represent an alternative scope for the control of this serious disease because it does not leave toxic chemical residues in honey nor in its by products.     

Chemical Composition and Biological Activity of the Essential Oil of Origanum vulgare ssp. hirtum from Different Areas in the Southern Apennines (Italy)

The chemical composition of the essential oils of Origanum vulgare ssp. hirtum, growing wild in three different localities in the Southern Apennines, was studied by GC‐FID and GC/MS analyses. In total, 103 compounds were identified. The oils were mainly composed of phenolic compounds and all oils belonged to the chemotype carvacrol/thymol. The three essential oils were evaluated for their in vitro phytotoxic activity by determining their influence on the germination and initial radicle elongation of Sinapis arvensis L., Phalaris canariensis L., Lepidium sativum L., and Raphanus sativus L. The seed germination and radicle growth were affected in various degrees. Moreover, the antifungal activity of the three essential oils was assayed against three species causing pre‐ and postharvest fruit decay (Monilinia laxa, M. fructigena, and M. fructicola). At 1000 ppm, the three oils completely inhibited fungal growth. The hemolytic activity of the oils was assayed and showed no effect on the cell membranes of bovine erythrocytes.     

Chemical and Olfactory Analysis of the Volatile Fraction of Ocimum gratissimum Concrete from Madagascar

The chemical composition of the volatile fraction of Ocimum gratissimum concrete (romba) from Madagascar has been determined for the first time by GC/MS and GC-FID. A methyl cinnamate chemotype has been determined for this material, along with a set of compounds typical in essential oils and extracts from plants of the Ocimum genus. Variability was mostly observed on terpenes and terpenoids components. GC-O-MS was also used for a sensory evaluation of this material performed by a master perfumer. The chemical composition of this O. gratissimum extract was then compared with literature data to assess subtle differences between chemotypes of the same species and other species of the same genus within natural variability. A mapping illustrates the occurrence of the cinnamate chemotype in Eastern Africa, India and now Madagascar, while other origins generally present eugenol, thymol, camphor, or linalool chemotypes.     

Species Differentiation and Quality Evaluation for Atractylodes Medicinal Plants by GC/MS Coupled with Chemometric Analysis

The utilization of rhizomes from the genus Atractylodes has been challenging due to their closely related origins. In this study, we developed an analytical strategy to differentiate Atractylodes lancea (A. lancea), Atractylodes chinensis (A. chinensis), Atractylodes japonica (A. japonica), and Atractylodes macrocephala (A. macrocephala), and compared their volatile compositions. Gas chromatography-mass spectrometry (GC/MS) was used to analyze the volatile profiles of essential oils extracted from 59 batches of samples. Chemometric methods enabled a better understanding of the differences in volatile oils between the four species and identified significant components affecting their classification and quality. A total of 50 volatile components were identified from the essential oils by GC/MS. Unsupervised and supervised chemometric analyses accurately distinguished A. lancea, A. chinensis, A. japonica, and A. macrocephala. Furthermore, five characteristic chemical markers, namely hinesol, β-eudesmol, atractylon, atractylodin and atractylenolide I, were obtained, and their respective percentage contents in individual species and samples were determined. This study provides a valuable reference for the quality evaluation of medicinal plants with essential oils and holds significance for species differentiation and the rational clinical application of Atractylodes herbs.