Composition, antioxidant and antimicrobial activities of leaf and twig essential oils of Litsea akoensis from Taiwan

This study analyzed the hydrodistilled essential oils in the leaves and twigs of Litsea akoensis to determine composition and yield. Seventy-one and 40 compounds were identified in the leaf and twig oils, respectively. The main components of leaf oil were limonene (18.5%), thymol (10.1%), p-cymene (9.6%), beta-caryophyllene (8.9%), and carvacrol (8.2%). The main components of twig oil were beta-phellandrene (43.7%) and trans-beta-ocimene (10.4%). The results demonstrated that leaf oil had excellent antioxidant and antimicrobial activities, superior to those of twig oil.     

Antimicrobial activity and chemical constituents of the essential oils from flower, leaf and stem of Gypsophila bicolor from Iran

The volatile constituents from flower, leaf and stem of Gypsophila bicolor growing in Iran were obtained by hydrodistillation and analyzed by GC and GC/MS. The flower oil was characterized by high amounts of germacrene-D (21.2%), p-cymene (20.6%), bicyclogermacrene (17.6%), gamma-dodecadienolactone (13.7%) and terpinolene (9.4%). Twenty-four constituents representing 97.4% of the leaf oil were identified of which germacrene-D (23.4%), terpinolene (14.5%), bicyclogermacrene (7.5%), gamma-dodecadienolactone (6.8%), p-cymene (6.7%) and cis-beta-ocimene (6.3%) were major components. The main components of the stem oil were gamma-dodecadienolactone (28.5%), bicyclogermacrene (14.8%), germacrene-D (12.6%), p-cymene (12.5%), terpinolene (11.6%) and trans-beta-ocimene (4.2%). The antimicrobial effects of flower, leaf and stem essential oils from Gypsophila bicolor were studied according to the agar diffusion cup method. The essential oils had a moderate effect on the Gram-positive and Gram-negative bacteria, but had a substantial effect on the fungi studied.     

Deuterium/hydrogen ratio analysis of thymol, carvacrol, gamma-terpinene and p-cymene in thyme, savory and oregano essential oils by gas chromatography-pyrolysis-isotope ratio mass spectrometry

Isotope ratio mass spectrometry online coupled with capillary gas chromatography (GC-Py-IRMS) on column INNOWAX is used in the origin specific analysis and the authenticity control of the phenolic essential oils (EOs). Isotopic data delta(2)H(V-SMOW) of thymol and carvacrol in natural essential oils were evidently more depleted than synthetic products (from -49 to 7 per thousand for thymol and -61 per thousand for carvacrol). delta(2)H(V-SMOW) values of p-cymene, gamma-terpinene and thymol in authentic thyme oils (Thymus vulgaris L. and Thymus zygis L.) were found from -300 to -270 per thousand, from -285 to -248 per thousand and from -259 to -234 per thousand, respectively. delta(2)H(V-SMOW) values of carvacrol and p-cymene in authentic oregano oils (Origanum heracleoticum L., Coridothymus capitatus L. and Origanum compactum L.) varied from -223 to -193 per thousand and from -284 to -259 per thousand, respectively. For authentic Satureja montana subsp. montana essential oils, the mean delta(2)H(V-SMOW) value for aromatic compounds were found to be the following: gamma-terpinene -273 per thousand (SD=4.6 per thousand) and p-cymene -283 per thousand (SD=3.0 per thousand), thymol -245 per thousand (SD=1.8 per thousand) and carvacrol -226 per thousand (SD=1.7 per thousand). In addition, p-cymene was previously found as a precursor of the biosynthesis of thymol and carvacrol in thyme oil, thus, we considered p-cymene as an endogenous reference compound (ERC) for D/H ratio analysis. The isotopic fractionation factors alpha(thymol/p-cymene)=1.05 and alpha(carvacrol/p-cymene)=1.08 were obtained and also used to control the authenticity of the phenolic EOs.     

Antimicrobial and antioxidant activities of essential oils of Satureja thymbra growing wild in Libya

The composition of essential oil isolated from Satureja thymbra, growing wild in Libya, was analyzed by GC and GC-MS. The essential oil was characterized by γ-terpinene (39.23%), thymol (25.16%), p-cymene (7.17%) and carvacrol (4.18%) as the major constituents. Antioxidant activity was analyzed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging method. It possessed strong antioxidant activity (IC50 = 0.0967 mg/mL). The essential oil was also screened for its antimicrobial activity against eight bacterial and eight fungal species, showing excellent antimicrobial activity against the microorganisms used, in particular against the fungi. The oil of S. thymbra showed bacteriostatic activity at 0.001-0.1 mg/mL and was bactericidal at 0.002-0.2 mg/mL; fungistatic effects at 0.001-0.025 mg/mL and fungicidal effects at 0.001-0.1 mg/mL. The main constituents thymol, carvacrol and γ-terpinene also showed strong antimicrobial activity. The commercial fungicide bifonazole showed much lower antifungal activity than the tested oil.     

Antioxidant, nitric oxide scavenging and malondialdehyde scavenging activities of essential oils from different chemotypes of Zataria multiflora

The antioxidant, nitric oxide (NO) scavenging and malondialdehyde (MDA) scavenging activities of different Zataria multiflora (ZM) chemotype essential oils (EOs) were investigated. The main components are: ZM1 (carvacrol, p-cymene), ZM2 (carvacrol, p-cymene), ZM3 (carvacrol, p-cymene), ZM4 (linalool), ZM5 (carvacrol, p-cymene, thymol), ZM6 (thymol, carvacrol, p-cymene, γ-terpienene), ZM7 (thymol, p-cymene, γ-terpienene) and ZM8 (carvacrol, linalool, p-cymene, thymol). The antioxidant capacities were estimated to be 863?±?55, 619?±?27, 876?±?32, 38?±?9, 649?±?50, 595?±?40, 696?±?41 and 618?±?9?μg ascorbic acid equivalents per millilitre for ZM1 to ZM8, respectively. The NO scavenging values were estimated to be 54?±?1.2, 50?±?1.4, 63?±?1, 0.60?±?0.1, 53?±?0.7, 53?±?1.5, 38?±?1.1 and 46.5?±?3?μg ascorbic acid equivalents per millilitre for ZM1 to ZM8, respectively. The MDA scavenging values were estimated to be 19?±?1, 9?±?1, 24?±?1, 1.6?±?0.6, 12?±?1, 11.7?±?1, 10?±?1 and 12.5?±?1.3?μg ascorbic acid equivalents per millilitre for ZM1 to ZM8, respectively. Among these EOs, ZM3 with carvacrol and p-cymene had higher antioxidant, NO scavenging and MDA scavenging properties.     

Chemical markers in Origanum vulgare L. from Kumaon Himalayas: a chemosystematic study

The essential oils of four wild growing Origanum vulgare L. (family Lamiaceae) collected from different locations in Kumaon region (Uttarakhand, India) were analysed by capillary GC and GC/MS. The comparative results of O. vulgare L. collected from four different regions showed differences in the chemical constituents of the essential oils. The oil of O. vulgare L. collected from Dhoulchina and Champawat (chemotype I) shows p-cymene (6.7-9.8%), γ-terpinene (12.4-14.0%), thymol (29.7-35.1%) and carvacrol (12.4-20.9%) as major constituents while the oil from Kilbury and Rushi village (chemotype II) shows linalool (6.7-9.7%), bornyl acetate (12.6-16.8%), β-caryophyllene (10.5-13.8%) and germacrene D (6.3-11.3%) as the major constituents. These features highlight the chemosystematics of this genus.     

Chemical composition and antibacterial activity of Origanum saccatum P.H. Davis essential oil obtained by solvent-free microwave extraction: comparison with hydrodistillation

The components of the essential oils (EOs) obtained by solvent-free microwave extraction (SFME) and hydrodistillation (HD) from endemic Origanum saccatum P.H. Davis were identified by using GC/MS. The main constituents of both EOs obtained by SFME and HD, respectively, from O. saccatum were p-cymene (72.5 and 70.6%), thymol (9.32 and 8.11%), and carvacrol (7.18 and 6.36%). The EO obtained by SFME contained substantially higher amounts of oxygenated compounds and lower amounts of monoterpenes than did the EO obtained by HD. The antibacterial activities of the EOs obtained by SFME and HD were evaluated with the disc diffusion method by comparison with 10 different bacterial strains. The antibacterial activity of the EO extracted by SFME was found to be more effective than that of the EO extracted by HD against seven of the tested bacteria.     

Essential oil polymorphism of wild growing Hungarian thyme (Thymus pannonicus) populations in the Carpathian Basin

The volatile oil compositions of Thymus pannonicus All. from nineteen different localities of Hungary were analyzed by GC/MS. The essential oil content of the Hungarian thyme samples varied between very low (0.14 mL/100 g DW) and fairly high (1.9 mL/100 g DW) values. Significant essential oil polymorphism was found: altogether twelve chemovarieties may have been determined, representing a way of adaptation to different habitat conditions. The main volatile compound of chemotype 1 was thymol (24.6-67.5%), while in the case of chemotype 2, thymol (36.5-63.7%) and p-cymene (11.5-27.3%) predominated. Thymol (28.4-63.7%), p-cymene (11.5-31.8%) and gamma-terpinene (9.7-20.9%) were identified as the chief monoterpenes of chemotype 3, while chemotype 4 contained thymol (36.5%), p-cymene (27.3%) and neral (11.2%). Chemotype 5 accumulated thymol (38.5%), p-cymene (20.6%), gamma-terpinene (12.0%) and beta-bisabolene (10.3%) as its main volatiles. The oil of chemotype 6 can be characterized by thymol (41.9%), p-cymene (20.2%), isoborneol (10.3%) and gamma-terpinene (9.9%), while that of chemotype 7 consisted of thymol (27.7%), linalyl acetate (18.8%), gamma-terpinene (18.6%) and alpha-cubebene (13.9%). In the oil of chemotype 8, p-cymene (45.0%), geraniol (13.6%) and linalyl acetate (9.9%) were found in higher percentages, while chemotype 9 mainly produced linalyl acetate (36.2%) and geranyl acetate (20.2%). Chemotype 10 accumulated germacrene-D (43.4) and beta-caryophyllene (15.0%), while the oil of chemotype 11 contained caryophyllene oxide (45.2%), alpha-cubebene (15.7%) and linalool (13.8%) in high proportions. Germacrene-D (29.7%), beta-caryophyllene (22.0%) and farnesol (10.4%) were identified as main essential oil compounds of chemotype 12. The last nine chemotypes were new for the literature, while the first seven contained thymol as their chief compound. The role of certain sesquiterpenes was found to be considerable.     

Analysis of essential oil of Satureja thymbra by hydrodistillation, thermal desorber, and headspace GC/MS techniques and its antimicrobial activity

The essential oil composition of Satureja thymbra was analyzed by direct thermal desorber and Headspace GC/MS analysis methods. Its constituents were determined to be mainly carvacrol (40.15%), gamma-terpinene (26.56%), p-cymene (16.39%), and thymol (13.16%). The other techniques, thermal desorber and Headspace GC/MS, were used for the plant leaves at three different temperature, which showed similar results. The thermal desorber GC/MS gave better and more sensitive results than Headspace GC/MS. The essential oil was found to be active against the bacteria Escherichia coli, Pseudomonas aeruginosa, Salmonella typhimurium, Shigella sonnei, and Staphylococcus aureus and the yeast Candida albicans.     

Essential Oils of Seven Lamiaceae Plants and Their Antioxidant Capacity

Oxidative stress has been reported as a cause of many diseases like Parkinson′s, Alzheimer′s, cardiovascular disease, and diabetes. Oxidative stress can also lead to cancer formation by promoting tumor development and progression. Antioxidants derived from Lamiaceae plants play an important role in natural medicine, pharmacology, cosmetology, and aromatherapy. Herein, we examine the antioxidative capacity of essential oils from seven aromatic Lamiaceae plants against the synthetic radicals DPPH and ABTS. Among the essential oils analyzed, the most robust scavenging capacities were found in mixtures of volatile compounds from thyme and savory. The scavenging activity of tested EOs against the ABTS radical was clearly higher than activity towards DPPH. Analysis of essential oils with weaker antioxidant activity has shown that volatile compounds from marjoram, sage, and hyssop were more active than EOs from lavender and mint. It can be suggested that the potent antioxidant capacity of thyme (Thymus vulgaris) and savory (Satyreja hortensis) are related to a high level of phenolic constituents, such as thymol and carvacrol. On the other hand, the elevated antioxidative power of marjoram, sage, and hyssop essential oils may also be due to their terpinene, o-cymene, terpinolene, and terpinen-4-ol constituents. Although non-phenolic components are less active than thymol or carvacrol, they may affect antioxidant capacity synergistically.     

Composition of the essential oil of Origanum tyttanthum from Tajikistan

Origanum tyttanthum Gontsch. was collected from two different sites in south-central Tajikistan. The essential oils were obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry. A total of 52 compounds were identified representing 99.0-100% of total oil compositions. The major components of Origanum tyttanthum Gontsch. oil were carvacrol (34.3-59.2%), thymol (10.8-46.4%), p-cymene (0.7-7.3%), beta-thujone (1.9-4.1%), piperitenone oxide (0.1-3.8%), gamma-terpinene (0.3-3.5%), cis-piperitone epoxide (0.8-3.3%), carvacrol acetate (0.4-2.4%), menthone (0.6-2.1%) and borneol (1.0-2.3%).     

Essential oil composition of aerial parts of Cyclospermum leptophyllum (Pers.) Sprague ex Britton and P. Wilson

The essential oil of Cyclospermum leptophyllum (Pers.) Sprague ex Britton and P. Wilson syn. Apium leptophyllum (Pers.) F. Muell. Ex Benth., family Apiaceae (Umbellifereae), was analysed by GC and GC-MS. The essential oil showed the presence of thymohydroquinone dimethyl ether (50.7%), thymol methyl ether (11.2%), γ-terpinene (10.4%), p-cymene (9.5%) and carvacrol methyl ether (5.9%), along with trans-ocimene, β-pinene, germacrene D, cumin aldehyde, α-humulene, β-myrcene, sabinene, limonene, β-phellandrene, caryophyllene oxide, α-pinene and α-thujene as minor constituents. To the best of our knowledge, this is the first study of the essential oil composition of C. leptophyllum collected from India.     

Chemical investigation of the essential oil of Thymus linearis (Benth. ex Benth) from western Himalaya, India

Thymus linearis (Benth. ex Benth) was collected from five distinct locations of western Himalaya (India) during the summer season. The hydro-distilled essential oil (yield 0.84-0.95%) was analysed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). A total of 56 constituents, representing 81.55% to 98.11% of the total oil composition, were identified. Thymol (52.28-66.65%), p-cymene (1.81-21.60%) and γ-terpinene (1.94-12.48%) were the major constituents in all populations. Other constituents identified in significant amounts were carvacrol, p-cymen-8-ol, borneol, terpinen-4-ol and thymol methyl ether. The presence of high phenol and essential oil contents in this species make it a suitable substitute for common thyme oil.     

Essential oil composition of aerial parts of Micromeria persica Boiss. from Western of Shiraz,Iran

Micromeria persica Boiss. is medicinal and aromatic plant, belonging to the Lamiaceae family. The chemical composition of the essential oils (EOs) from aerial parts of M. persica were extracted using hydro-distillation method and analysed using GC and GC–MS. Fifty-two compounds were identified in the EOs of aerial parts of M. persica. The main chemical compositions were n-hexadecanoic acid (14.9%), thymol (9.5%), linoleic acid (8.0%), carvacrol (5.6%), (E)-nerolidol (5.5%), linolenic acid (5.5%), α-cadinol (2.7%), linalool (2.7%), borneol (2.6%), caryophyllene oxide (2.3%) and pulegone (2.0%). Presence of borneol, thymol, carvacrol and pulegone suggests the potential of this plant as a flavouring source in the food industry, being used in perfumery and cosmetics industry, vitamin E synthesis and exhibit strong fungicidal, antibacterial and antimicrobial activities.     

Volatile organic compounds from Centaurium erythraea Rafn (Croatia) and the antimicrobial potential of its essential oil

GC and MS were used for the analysis of Croatian Centaurium erythraea Rafn essential oil (obtained by hydrodistillation) and headspace (applying headspace solid-phase microextraction). The headspace contained numerous monoterpene hydrocarbons (the major ones were terpinene-4-ol, methone, p-cymene, γ-terpinene and limonene). Oxygenated monoterpenes were present in the headspace and oil, while 1,8-cineole, bornyl acetate and verbenone were present only in the headspace. High headspace percentages of toluene and naphthalene were found, followed by hemimellitene. Lot of similarities were observed with Serbian C. erythraea oil [neophytadiene (1.4%), thymol (2.6%), carvacrol (6.1%) and hexadecanoic acid (5.7%)], but different features were also noted such as the presence of menthol, menthone and phytone. The oil fractionation enabled identification of other minor compounds not found in total oil such as norisoprenoides, alk-1-enes or chromolaenin. The essential oil showed antimicrobial potential on Escherichia coli, Salmonella enteritidis, Staphylococcus aureus and Bacillus cereus. On the other hand, no antibacterial activity of the oil was observed on Pseudomonas fluorescens and Lysteria monocytogenes.     

Chemical composition, antibacterial and antioxidant activities of the essential oils from Thymus satureioides and Thymus pallidus

This study was designed to examine the in vitro antibacterial and antioxidant activities of the essential oils (EOs) of Thymus satureioides (T.s) and T. pallidus (T.p). EOs were isolated by steam distillation and analyzed by capillary gas chromatography and gas chromatography coupled to mass spectrometry (GC-MS). The major constituents of the volatile fraction of T. satureioides were bomeol (29.5%), carvacrol (9.1%), and beta-caryophyllene (8.2%), while those of T. pallidus were camphor (29.8%), dihydrocarvone (17.6%), bomeol (7.6%) and camphene (7.5%). The essential oils were tested against a panel of Gram+ and Gram- bacteria by using agar diffusion and broth dilution methods. The data indicated that the Gram-positive Bacillus subtilis was the most sensitive strain producing an average inhibition zone of 51.7 mm. Furthermore, Pseudomonas aeruginosa, known as a resistant strain, was also sensitive. The samples were also subjected to screening for their possible antioxidant activity by using the 2,2-diphenyl-l-picrylhydrazyl (DPPH) assay. The IC50 values of the oil of T. satureioides and T. pallidus were 0.32 and 11.6 mg/mL, respectively.     

The composition and antimicrobial activities of Cyperus conglomeratus, Desmos chinensis var. lawii and Cyathocalyx zeylanicus essential oils

The essential oil compositions of the rhizomes of Cyperus conglomeratus (Cyperaceae) collected from Oman and the leaves of two Annonaceae plants, Desmos chinensis var. lawii and Cyathocalyx zeylanicus collected from India were studied by GC, GC-MS and 13C NMR spectroscopy. Twenty-six compounds, representing 84.4% of the oil were identified in C. conglomeratus, where eugenol (31.3%), alpha-cyperone (10.5%) and cyperotundone (8.4%) were the major compounds. Twelve compounds, constituting 100%, were identified in D. lawii oil, of which benzyl benzoate (58.7%), beta-caryophyllene (23.2%), limonene (4.9%) and alpha-humulene (4.0%) were the major constituents. Thirty-two compounds, comprising 98.0%, were identified in C. zeylanicus oil, of which beta-caryophyllene (21.6%), alpha-pinene (20.4%) and E-beta-ocimene (11.8%) were the major components. The antibacterial and antifungal activities of the oils were tested against a panel of five bacterial and two fungal strains. The oils showed moderate activity against all the tested microbial strains. The minimum inhibitory concentrations of the oils were also determined.     

Composition, antioxidant and antimicrobial activities of the leaf essential oil of Machilus japonica from Taiwan

The chemical composition, and antioxidant and antimicrobial activities of the essential oil isolated from the leaf of Machilus japonica from Taiwan have been investigated. The essential oil from the fresh leaves was isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC-FID and GC-MS. A total of 97 compounds were identified, representing 100% of the oil. The main components identified were alpha-phellandrene (14.5%), alpha-pinene (12.8%), thymol (12.6%), beta-pinene (8.3%), alpha-terpineol (6.5%) and carvacrol (6.0%). The antioxidant activity of the oil was tested by the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging capability test. The results showed that the IC50 was 51.8 microg/mL. The antimicrobial activity of the oil was tested by the disc diffusion and micro-broth dilution methods against ten microbial species. The oil exhibited strong growth suppression against Gram-positive bacteria and yeast, with inhibition zones of 48-54 mm and MIC values of 16.12-32.25 microg/mL, respectively. For the antioxidant and antimicrobial activities of the oil, the active source compounds were determined to be thymol and carvacrol.     

Composition and antimicrobial activities of Lippia multiflora Moldenke, Mentha x piperita L. and Ocimum basilicum L. essential oils and their major monoterpene alcohols alone and in combination

Essential oils from leaves of Lippia multiflora, Mentha x piperita and Ocimum basilicum from Burkina Faso were analysed by GC-FID and GC-MS. Major components were p-cymene, thymol, b-caryophyllene, carvacrol and carvone for L. multiflora, menthol and iso-menthone for M. x piperita and, linalool and eugenol for O. basilicum. The essential oils and their major monoterpene alcohols were tested against nine bacterial strains using the disc diffusion and broth microdilution methods. The essential oils with high phenolic contents were the most effective antimicrobials. The checkerboard method was used to quantify the efficacy of paired combinations of essential oils and their major components. The best synergetic effects among essential oils and major components were obtained with combinations involving O. basilicum essential oil and eugenol, respectively. As phenolic components are characterized by a strong spicy aroma, this study suggests that the selection of certain combinations of EOs could help to reduce the amount of essential oils and consequently reduce any adverse sensory impact in food.     

Antibacterial activities of essential oils extracted from leaves of Murraya koenigii by solvent-free microwave extraction and hydro-distillation

Solvent-free microwave extraction (SFME) for the isolation of essential oil from leaves of Murraya koenigii L. (Rutaceae) has been compared with the conventional hydro-distilled oil (HD) in terms of yield, composition, antioxidant activity, and antibacterial activity against Listeria innocua. The yield of essential oil obtained from 30 min of SFME was similar to that of HD for 180 min. By GC-MS analysis, the major compounds of the essential oil extracted by SFME, which were obtained in somewhat lower amounts than in the essential oil obtained by HD, were alpha-copaene (44.3%), beta-gurjunene (25.5%), isocaryophyllene (12.1%), beta-caryophyllene (8.7%) and germacrene D (2.9%). The content of oxygenated terpenes, slightly higher for the SFME-essential oil (2.3%) than the HD-essential oil (1.4%), were much lower than that of nonoxygenated terpenes in both oils. DPPH radical scavenging activities of both essential oils were relatively low (10%-24%). Complete inhibition of growth of L. innocua was observed with both SFME and HD essential oils, at 400 and 600 microg/mL (minimum inhibitory concentration), respectively. The SFME-essential oil at 300 microg/mL provided 92% inhibition, indicating its potential as a natural antimicrobial agent.