Variation of the Chemical Composition and Antimicrobial Activity of the Essential Oils of Natural Populations of Tunisian Daucus carota L. (Apiaceae)

The essential oils of Daucus carota L. (Apiaceae) seeds sampled from ten wild populations spread over northern Tunisia were characterized by GC‐FID and GC/MS analyses. In total, 36 compounds were identified in the D. carota seed essential oils, with a predominance of sesquiterpene hydrocarbons in most samples (22.63–89.93% of the total oil composition). The main volatile compounds identified were β‐bisabolene (mean content of 39.33%), sabinene (8.53%), geranyl acetate (7.12%), and elemicin (6.26%). The volatile composition varied significantly across the populations, even for oils of populations harvested in similar areas. The chemometric principal component analysis and the hierarchical clustering identified four groups, each corresponding to a composition‐specific chemotype. The in vitro antimicrobial activity of the isolated essential oils was preliminarily evaluated, using the disk‐diffusion method, against one Gram‐positive (Staphylococcus aureus) and two Gram‐negative bacteria (Escherichia coli and Salmonella typhimurium), as well as against a pathogenic yeast (Candida albicans). All tested essential oils exhibited interesting antibacterial and antifungal activities against the assayed microorganisms.     

Chemical Composition and Biological Activities of the Essential Oil from Leaves and Flowers of Pulicaria incisa sub. candolleana (Family Asteraceae)

The composition of the essential oil isolated from leaves and flowers of Pulicaria incisa sub. candolleana E. Gamal ‐Eldin , growing in Egypt, was analysed by GC and GC‐MS. Forty‐nine and 68 compounds were identified from the oils of the leaves and flowers accounting for 86.69 and 84.29%, respectively of the total detected constituents. Both leaves and flowers oils were characterized by the high content of carvotanacetone with 66.01, 50.87 and chrysanthenone 13.26, 24.3%, respectively. The cytotoxic activity of both essential oils was evaluated against hepatocellular carcinoma cell line HEPG‐2, using MTT assay and vinblastine as a reference drug. Leaf oil showed higher activity with IC₅₀ 11.4 μg/ml compared with 37.4 μg/ml for flower oil. The antimicrobial activity of both oils was evaluated using agar well diffusion method towards two representatives for each of Gram positive and Gram negative bacteria as well as four representatives for fungi. The minimum inhibitory concentration of both essential oils against bacterial and fungal strains was obtained in the range of 0.49 – 15.63 μg/ml.     

Chemical Composition of the Leaf and Flower Essential Oils of Tunisian Lavandula dentata L. (Lamiaceae)

Essential oils of Lavandula dentata, a Tunisian native plant, were isolated from leaves and flowers by hydrodistillation in a Clevenger‐type apparatus and characterized by GC‐FID and GC/MS analyses. The average essential oil yields, means of five replicates, were higher for the flowers (8.60 mg/g) than for the leaves (6.56 mg/g). A total of 72 compounds were identified, accounting for 98.1 and 97.7% of the total oil composition of the leaves and flowers, respectively. The main essential oil constituents were 1,8‐cineole, camphor, and L ‐fenchone, accounting for 33.54, 18.89, and 8.36% in the leaf oils and for 19.85, 23.33, and 7.13% in the flower oils, respectively. Besides this quantitative variation, the results also showed considerable qualitative variation between the essential oils of the two plant parts analyzed. These differences might be adaptative responses to ecological exigencies.     

Chemical Composition and Antimicrobial and Allelopathic Activity of Tunisian Conyza sumatrensis (Retz.) E.Walker Essential Oils

Conyza sumatrensis (Retz.) E.Walker (Asteraceae) is a spontaneous annual herb, fairly widespread throughout Tunisia, which has rarely been studied or valued in any sector. Essential oils were obtained by hydrodistillation of different parts (flower heads, leaves, stems, and roots) of C. sumatrensis plants, which were collected in autumn (November 2007) at the flowering stage in the area of Monastir, Tunisia. In total, 98 compounds, representing 88.1–99.3% of the oil composition, were identified by GC‐FID and GC/MS analyses. The root essential oil was distinguished by its high content in acetylenes (matricaria ester, 4 ; 74.3%), while those from flower heads and leaves were dominated by oxygenated sesquiterpenes (61.1 and 50.3%, resp.). The oils of C. sumatrensis from Tunisia belonged to a matricaria ester/caryophyllene oxide chemotype. All the oils were evaluated for antibacterial, antifungal, and allelopathic activities. The results indicate that the leaf oil exhibited significant in vitro antibacterial activity against Enterococcus faecalis, Staphylococcus aureus, and Proteus mirabilis and that the C. sumatrensis oils isolated from the aerial parts presented high mycelia‐growth inhibition of Candida albicans and the filamentous fungi tested. Moreover, the essential oils of the different plant parts inhibited the shoot and root growth of Raphanus sativus (radish) seedlings. Indeed, the inhibition of the hypocotyl growth varied from 28.6 to 90.1% and that of the radicle from 42.3 to 96.2%.     

赤楠叶精油的化学成分及其抗菌活性

以水蒸汽蒸馏法提取赤楠叶精油,得率约0．51％,用GC-MS分析其化学成分,主要为石竹烯(37．623％)、α-瑟林烯(9.627％)、β-瑟林烯(9．408％)、柯巴烯(5．360％)等。抗菌实验显示该精油对金黄色葡萄球菌、枯草芽孢杆菌、大肠杆菌、普通变形杆菌、藤黄八叠球菌等具有较强的抑杀活性。     

Chemical Composition and Biological Activities of Tunisian Cupressus arizonica Greene Essential Oils

The chemical composition of the essential oils obtained by hydrodistillation of leaves, stems, and female cones of Cupressus arizonica Greene , grown in Tunisia, was studied by GC‐FID and GC/MS analyses. Altogether, 62 compounds were identified, 62 in the leaf oil, 19 in the cone oil, and 24 in the stem oil. The cone and stem oils were mainly composed by monoterpene hydrocarbons (96.6 and 85.2%, resp.). In the leaf oil, the total sesquiterpene fraction constituted 36.1% and that of the monoterpene hydrocarbons 33.8% of the total oil composition. The three oils were evaluated for their in vitro herbicidal activity by determining their influence on the germination and the shoot and root growth of the four weed species Sinapis arvensis L., Lolium rigidum Gaudin , Trifolium campestre Schreb ., and Phalaris canariensis L. At the highest doses tested (0.8 and 1.0 mg/ml), the leaf essential oil inhibited either totally or almost completely the seed germination and the shoot and root growth of S. arvensis and T. campestre. The oils were also tested for their antifungal activity; however, their effects on the fungal growth were statistically not significant.     

Chemical Composition of the Tuber Essential Oil from Helianthus tuberosus L. (Asteraceae)

Helianthus tuberosus L. (Jerusalem artichoke) is cultivated in Europe and other parts of the world as a food crop and ornamental plant. The volatile oils of the aerial parts of H. tuberosus were investigated more than 30 years ago, but no study could be found to date on the constituents of the tuber essential oil. Herein, the first characterization by GC‐FID, GC/MS, and ¹³C‐NMR analyses of a hydrodistilled essential oil of Jerusalem artichoke tubers was reported. Fresh plant material collected in Serbia (Sample A) and a commercial sample (Sample B) yielded only small amounts of oil (0.0014 and 0.0021% (w/w), resp.). In total, 195 constituents were identified, representing 88.2 and 93.6% of the oil compositions for Samples A and B, respectively. The main constituents identified were β‐bisabolene ( 1 ; 22.9–30.5%), undecanal (0–12.7%), α‐pinene (7.6–0.8%), kauran‐16‐ol ( 2 ; 6.9–9.8%), 2‐pentylfuran (0.0–5.7%), and (E)‐tetradec‐2‐enal (0.0–4.9%). Several rare compounds characteristic for Helianthus ssp. were also detected: helianthol A ( 6 ; 2.1–1.9%), dihydroeuparin ( 10 ; 0.0–2.3%), euparin ( 9 ; 0.0–0.4%), desmethoxyencecalin ( 7 ; traces – 0.2%), desmethylencecalin ( 8 ; 0.0–0.4%), and an isomer of desmethylencecalin (0.0%‐traces). The essential oils isolated from the tuber and the aerial parts share the common major component 1 .     

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.     

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.     

Chemical Composition and Allelopathic Potential of Essential Oils from Tipuana tipu (Benth.) Kuntze Cultivated in Tunisia

In Tunisia, Tipuana tipu (Benth .) Kuntze is an exotic tree, which was introduced many years ago and planted as ornamental street, garden, and park tree. The present work reported, for the first time, the chemical composition and evaluates the allelopathic effect of the hydrodistilled essential oils of the different parts of this tree, viz., roots, stems, leaves, flowers, and pods gathered in the area of Sousse, a coastal region, in the East of Tunisia. In total, 86 compounds representing 89.9 – 94.9% of the whole oil composition, were identified in these oils by GC‐FID and GC/MS analyses. The root essential oil was clearly distinguished for its high content in sesquiterpene hydrocarbons (β‐caryophyllene, 1 (44); 24.1% and germacrene D, 2 (53); 20.0%), while those obtained from pods, leaves, stems, and flowers were dominated by non‐terpene hydrocarbons. The most important ones were n‐tetradecane (41, 16.3%, pod oil), 1,7‐dimethylnaphthalene (43, 15.6%, leaf oil), and n‐octadecane (77, 13.1%, stem oil). The leaf oil was rich in the apocarotene (E)‐β‐ionone ( 4 (54); 33.8%), and the oil obtained from flowers was characterized by hexahydrofarnesylacetone ( 5 (81); 19.9%) and methyl hexadecanoate (83, 10.2%). Principal component and hierarchical cluster analyses separated the five essential oils into three groups and two subgroups, each characterized by the major oil constituents. Contact tests showed that the germination of lettuce seeds was totally inhibited by the root essential oil tested at 1 mg/ml. The inhibitory effect on the shoot and root elongation varied from ?1.6% to ?32.4%, and from ?2.5% to ?64.4%, respectively.     

Chemical Composition and Allelopathic Potential of Essential Oils from Citharexylum spinosum L. Grown in Tunisia

Citharexylum spinosum L. (Verbenaceae) also known as Citharexylum quadrangulare Jacq . or Citharexylum fruticosum L. is an exotic tree introduced many years ago in Tunisia, specially used as a street and park ornamental tree. Essential oils (EOs) were obtained by hydrodistillation of the different parts (roots, stems, leaves, flowers and fruits; drupes) collected from trees grown in the area of Monastir (Tunisia). In total, 84 compounds, representing 90.1 – 98.4% of the whole oil composition, were identified by GC‐FID and GC/MS analyses. The root EO was distinguished by its high content in monoterpene hydrocarbons (α‐phellandrene; 30.8%) whereas that obtained from stems was dominated by sesquiterpene hydrocarbons (cuparene; 16.4%). The leaf oil was rich in an apocarotenoid derivative (hexahydrofarnesylacetone; 26%) and an aliphatic hydrocarbon (nonadecane; 14.5%). Flowers oil was rich in esters (2‐phenylethyl benzoate; 33.5%). Finally, drupes oil was rich in oxygenated sesquiterpenes (β‐eudesmol; 33.1%). Flowers oil showed a significant phytotoxic effect against lettuce seeds germination, it induces a total inhibition when tested at 1 mg/ml. Root and shoot elongation seemed to be more affected than germination. The inhibition of the shoot length varied from 3.6% to 100% and that of the root from 16.1% to 100%. The highest inhibition of 100% was detected for flower oil tested at 1 mg/ml. Our in vitro studies suggest a possible and new alternative use of C. spinosum EOs in herbicidal formulations, further experiments involving field conditions are necessary to confirm its herbicidal potential.     

Seasonal and Geographical Influences on the Chemical Composition of Juniperus phoenicea L. Essential Oil Leaves from the Northern Tunisia

The essential‐oil composition of 60 individual trees of Juniperus phoenicea L. from four Tunisian populations in three different periods were investigated by GC and GC/MS analyses. 59 Compounds were identified in the oils, and a relatively high variation in their contents was found. All the oils were dominated by the terpenic hydrocarbon fraction, and the main component was α‐pinene (20.28–40.86%). The results of the oil compositions were processed by hierarchical clustering and principal component analysis (PCA) allowing establishing four groups of essential‐oils differentiated by one compound or more. Pattern of geographic variation in essential‐oil composition indicated that individuals from the continental site (Makthar) were clearly distinguished from those from littoral localities (Tabarka, Hawaria, and Rimel).     

Chemical Composition and Aroma Evaluation of Essential Oils from Evolvulus alsinoides L.

The aim of this study was to investigate the chemical composition and the odor‐active compounds of the essential oils from Evolvulus alsinoides, which is a well‐known edible and medicinal plant. The volatile compounds in the oils were identified by hydrodistillation (HD) and solvent‐assisted flavor evaporation (SAFE) in combination with GC, GC/MS, GC/O (=olfactometry), aroma extract dilution analysis (AEDA), and relative flavor activities (RFA values). The most abundant compound in the HD oil was cis‐α‐necrodol (12.62%), an irregular monoterpene with a cyclopentane skeleton, which is very unusual in the plant kingdom. In the SAFE oil, the main components included 2‐butoxyethanol (9.01%), benzyl alcohol (8.01%), and γ‐butyrolactone (7.37%). Through sensory analysis, 21 aroma‐active compounds were identified by GC/O. The most intense aroma‐active compounds in the HD oil were hexan‐1‐ol and γ‐nonalactone, both of which showed high RFA values. α‐Methyl‐γ‐butyrolactone and dimethyl sulfone contributed more strongly to the aroma of the SAFE oil. These results imply that the essential oils of E. alsinoides deserve further investigation in the food industry.     

假烟叶树叶挥发油化学成分分析

采用水蒸汽蒸馏法、两相溶剂萃取法提取,运用毛细管气相色谱-质谱联用法结合计算机检索对茄科植物假烟叶树(Solanum verbascifoliumL.)叶挥发油的化学成分进行分析和鉴定。其新鲜叶片提取10 h的挥发油得率为0.0611%。经毛细管色谱分离出18个峰,共鉴定出17种化合物,占挥发油总量的99.73%;用气相色谱面积归一化法计算各组分的相对含量,其主要化学成分为:大牻牛儿烯D(37.07%),咕巴烯(26.29%),1β-(1-甲基乙基)-4,7-二甲基-1α,2,4a()β,5,8,8a()α-六氢萘(13.63%),石竹烯(8.03%),1-β乙烯基-1-α甲基-2,β4-β双(1-甲基乙烯基)-环己烷(5.81%),-γ榄香烯(2.16%),α-筚澄茄油烯(2.06%),异喇叭烯(0.98%)。以上8种化合物占总挥发油含量的90.22%。     

Chemical Composition and Interpopulation Variability of Essential Oils of Taxus baccata L. from Serbia

The composition of the essential oil of the twigs and needles of Taxus baccata L. from three natural populations in Serbia has been determined by GC/MS analysis. Of the 91 detected compounds, 87 were identified. The most abundant compound classes were aliphatic alcohols, terpenes, aliphatic hydrocarbons, and aliphatic aldehydes, which together comprised ca. 86.92% of the total oil composition. The dominant constituents were oct‐1‐en‐3‐ol (23.48%), (3Z)‐hex‐3‐en‐1‐ol (11.46%; aliphatic alcohols), and myrtenol (11.38%; oxygenated monoterpene). The PCA of 22 selected compounds revealed differentiations of populations based on geographic distribution. The CA showed that Populations I and II from the Dinaric Alps were similar, and that Population III from the Balkan mountain system was distinct. This was the first investigation of interpopulation variability of T. baccata populations based on essential oil composition. The results of this study were compared with those of previous studies concerning volatile compounds produced by Taxus species. The results indicate that the essential oil content of T. baccata populations from this study is unique, mostly resembling the population from southeast Serbia.     

Essential Oils from Piper caldense C. DC. and Piper xylosteoides (Kunth) Steud.: Seasonal Variation of the Chemical Composition and Antimicrobial Activity

The essential oils (EOs) chemical composition can be affected by several environmental factors, impacting their desired biological activities. In this sense, this work aimed to evaluate the seasonal variation of the chemical composition and antimicrobial activity of Piper caldense and Piper xylosteoides leaves EOs. Their chemical composition was determined by GC/MS and GC-FID analyses, resulting in the identification of eighty compounds. P. caldense EOs were mainly consisted of sesquiterpene hydrocarbons, whereas in P. xylosteoides EOs, monoterpene hydrocarbons were predominant. EOs from both species strongly inhibited B. subtilis (MIC=0.25 mg mL⁻¹), while only P. caldense EOs showed strong activity against S. aureus (MIC=0.50 mg mL⁻¹). P. caldense spring EO showed the broadest spectrum of antimicrobial action amongst all samples. For each species, PCA seasonally differentiated EOs chemical composition. In addition, as expected, PCA of all samples showed a distinction between the two species. This study has successfully demonstrated the importance of evaluating the seasonal variation of EOs chemical composition and antimicrobial activity in obtaining a product with the desired properties.     

Study on Essential Oil Composition in Leaves of Pseudotaxus chienii (Cheng) Cheng and Its Chemotaxonomy

The chemical components of different genera and species of Taxaceae have been analyzed in order to provide data for discussion of the systematic position of this family. A characteristic component tsugalacton (or tsugaresinol) from trunk of Pseudotaxus chienii (Cheng) Cheng has been reported in our previous paper. The present paper deals with our preliminary study on essential oil composition of leaves in the same species. Thirt-eight components have been isolated and 33 of them have been identified. Three of them, limonene, α-pinene, and δ-3-carene, are the main ones, with their contents being more than 1/3 in the total essential oil. This characteristic of the essential oil composition from leaves of Pseu- dotaxus chienii resembles to that of Torreya grandis cv. ‘Merrillii’.     

Essential Oil Composition of Phagnalon sordidum (L.) from Corsica,Chemical Variability and Antimicrobial Activity

The chemical composition of Phagnalon sordidum (L.) essential oil was investigated for the first time using gas chromatography and chromatography/mass spectrometry. Seventy‐six compounds, which accounted for 87.9% of the total amount, were identified in a collective essential oil of P. sordidum from Corsica. The main essential oil components were (E)‐β‐caryophyllene (14.4%), β‐pinene (11.0%), thymol (9.0%), and hexadecanoic acid (5.3%). The chemical compositions of essential oils from 19 Corsican locations were investigated. The study of the chemical variability using statistical analysis allowed identifying direct correlation between the three populations of P. sordidum widespread in Corsica and the essential oil compositions they produce. The in vitro antimicrobial activity of P. sordidum essential oil was evaluated and it exhibited a notable activity on a large panel of clinically significant microorganisms.     

Chemical Composition of Volatiles; Antimicrobial,Antioxidant and Cholinesterase Inhibitory Activity of Chaerophyllum aromaticum L. (Apiaceae) Essential Oils and Extracts

The present study reports the chemical composition of the headspace volatiles (HS) and essential oils obtained from fresh Chaerophyllum aromaticum root and aerial parts in full vegetative phase, as well as biological activities of their essential oils and MeOH extracts. In HS samples, the most dominant components were monoterpene hydrocarbons. On the other hand, the essential oils consisted mainly of sesquiterpenoids, representing 73.4% of the root and 63.4% of the aerial parts essential oil. The results of antibacterial assay showed that the aerial parts essential oil and MeOH extract have no antibacterial activity, while the root essential oil and extract showed some activity. Both of the tested essential oils exhibited anticholinesterase activity (47.65% and 50.88%, respectively); MeOH extract of the root showed only 8.40% inhibition, while aerial part extract acted as an activator of cholinesterase. Regarding the antioxidant activity, extracts were found to be more effective than the essential oils.     

Chemical Composition of the Essential Oils from Different Morphological Parts of Pinus cembra L.

The essential oils from needles, twigs, bark, wood, and cones of Pinus cembra were analyzed by GC‐FID, GC/MS, and ¹H‐NMR spectroscopy. More than 130 compounds were identified. The oils differed in the quantitative composition. The principal components of the oil from twigs with needles were α‐pinene (36.3%), limonene (22.7%) and β‐phellandrene (12.0%). The needle oil was dominated by α‐pinene (48.4%), whereas in the oil from bark and in the oil from twigs without needles there were limonene (36.2% and 33.6%, resp.) and β‐phellandrene (18.8% and 17.1%, resp.). The main constituents of the wood oil as well as cone oil were α‐pinene (35.2% and 39.0%, resp.) and β‐pinene (10.4% and 18.9%, resp.). The wood oil and the cone oil contained large amounts of oxygenated diterpenes in comparison with needle, twig, and bark oils.