Chemical composition and antimicrobial properties of essential oils of three Australian Eucalyptus species

The chemical composition and antimicrobial properties of the essential oils of three common Australian Eucalyptus species, namely E. olida, E. staigeriana and E. dives were determined by gas chromatography/mass spectrometry and the agar disc diffusion method, respectively. A total of 24 compounds were identified from the essential oil of E. dives, with the dominant compounds being piperitone (40.5%), α-phellandrene (17.4%), p-cymene (8.5%) and terpin-4-ol (4.7%). For E. staigeriana, 29 compounds were identified with 1,8-cineole (34.8%), neral (10.8%), geranial (10.8%), α-phellandrene (8.8%) and methyl geranate (5.2%) being the dominant ones. In contrast, a single compound, (E)-methyl cinnamate, accounted for 99.4% of the essential oils of E. oilda, although 20 compounds were identified. The essential oils displayed a variable degree of antimicrobial activity with E. staigeriana oil showing the highest activity. In general, Gram-positive bacteria were found to be more sensitive to the essential oils than Gram-negative bacteria. Staphylococcus aureus was the most sensitive strain while Pseudomonas aeruginosa was the most resistant.     

Phytochemical composition and antimicrobial activities of the essential oils from Satureja subspicata Vis. growing in Croatia

The present study describes the phytochemical profile and antimicrobial activity of Satureja subspicata Vis. essential oils, collected in Dalmatia (Croatia). Three samples of essential oils were obtained from the aerial parts of the plant by hydrodistillation and analyzed by GC–MS. From the 24 compounds representing 97.47% of the oils, carvacrol (16.76%), α-pinene (13.58), p-cymene (10.76%), γ-terpinene (9.54%) and thymol methyl ether (8.83%) appear as the main components. The oils also contained smaller percentages of myrcene, linalool, β-caryophyllene, limonene, geranyl acetate, 1-Octen-3-ol, nerol, thymol and borneol. Furthermore, antimicrobial activity of the oil was evaluated using agar diffusion and broth microdilution methods. The antimicrobial test results showed that the oils had a great potential antimicrobial activity against all 13 bacteria and 9 fungal strains. Gram-positive bacteria are more sensitive to the investigated oil, with a range of 0.09 to 6.25 μl/ml than Gram-negative bacteria in the range which is significantly higher from 1.56 to 25.00 μl/ml. Results presented here may suggest that the essential oil of S. subspicata possesses antimicrobial properties, and is therefore a potential source of antimicrobial ingredients for the food and pharmaceutical industry.     

Essential oils of Lavandula bipinnata and their antimicrobial activities

The essential oils from dried leaves of Lavandula bipinnata (Roth) Kuntze (Lamiaceae), obtained by soxhlet extraction was analysed by gas chromatography–mass spectrometry (GC–MS) and was evaluated for in vitro antimicrobial activity. The most common components usually found in lavender essential oils were present in the oil samples analysed, out of 43 peaks, 29 components, which constitute 72.38%, were identified in the essential oil. The major constituents were transcarveol (18.93%), pulegone (8.45%), camphor (7.09%) and menthol (5.89%). Other constituents present in fairly good amounts are pipertone (4.65%), caryophyllene oxide (3.68%), linalyl acetate (3.37%) and bicyclogermacrene (3.09%). The essential oil was screened for antimicrobial activity by disc diffusion assay and minimum inhibitory concentration (MIC) against bacteria and fungus. Results reveal that L. bipinnata essential oils are inhibitory against the tested bacteria and fungal strains.     

Composition and biological activities of essential oils from four Heracleum species

The composition of essential oils from aerial parts of Heracleum persicum, a widely used medicinal plant, and three other Heracleum species growing wild in Iran were analysed by GC and GC–MS. Myristicin (53.6%), (E)-anethole (25.0%), hexyl butanoate (29.7%) and elemicin (41.1%) were the major compounds of Heracleum pastinacifolium, H. persicum, Heracleum rechingeri and Heracleum transcaucasicum, respectively. Cytotoxic activity assessed on three human cancer cell lines (HeLa, LS180 and Raji), showed that essential oils from H. transcaucasicum (IC₅₀ values; 0.362–0.594 mg/ml) followed by H. pastinacifolium (0.497–1.398 mg/ml) had moderate antitumoral activities. In the DPPH radical scavenging assay, H. pastinacifolium and H. persicum oils showed the highest activities with IC₅₀ values of 7.3 and 7.4 mg/ml, respectively. Antioxidant activity correlated well with the total phenolic content of the oils. None of the essential oils showed significant antimicrobial activities.     

Chemical composition and antioxidant and antimicrobial activity of two Satureja essential oils

Hydro-distilled volatile oils from the aerial parts of Satureja montana L., and Satureja subspicata Bartl. ex Vis., growing wild in Bosnia and Herzegovina, were analyzed by GC/MS. More than one hundred compounds were identified in both plant oils, representing 92.4–98.1% of the total oil. The major constituents of essential oils obtained from the plant material of S. montana, collected from two different localities, were thymol (31.7%), and geraniol (22.3%), respectively. The most abundant compounds in essential oils of S. subspicata, collected at two different stages of development, were thymol (28.6%), and spathulenol (37.6%), respectively. The screening of antimicrobial activity of essential oil samples was individually evaluated against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis using a paper disc diffusion method. All tested microorganisms were inhibited by essential oil samples. Antioxidant activity was tested using the DPPH radical-scavenging method. All samples showed activity comparable to thymol, which was used as a positive probe.     

Composition and antimicrobial activity of the essential oils of three Satureja species growing in Tanzania

Hydro-distilled volatile oils from the aerial parts of three Satureja species were investigated, mainly by a combination of GC and GC/MS. One hundred and thirteen compounds were identified, representing 82.9–92.0% of the total oil. Among the identified components, spathulenol, cis-piperitone oxide, α-bisabolol oxide-B, terpinen-4-ol, linalool, bornyl acetate, β-bourbonene, isomenthone, thymol, neoisomenthol and menthone were found as the main components. Furthermore, the essential oils were investigated for their antimicrobial activity, by the agar dilution technique. The antimicrobial test results showed that the oils had a high antimicrobial activity against two Gram-positive and four Gram-negative bacteria, two oral pathogens and three pathogenic fungi. Gram-positive bacteria were more sensitive to the investigated oils than were Gram-negative bacteria. These results could support the suggestion of Satureja species as a source of antimicrobial ingredients for the food industry.     

Essential oils of Alpinia conchigera Griff. and their antimicrobial activities

The essential oils from the dried leaves, pseudostems and rhizomes of Alpinia conchigera Griff. (KL 5049), collected from Jeli province of Kelantan, east coast of Peninsular Malaysia, were isolated by hydrodistillation. The collected oils were analyzed by capillary GC and GC–MS. Forty one compounds were identified, among which 13 have not been detected previously. The leaf, pseudostem and rhizome oils afforded 40, 33 and 39 constituents, respectively. The most abundant components in the leaf oil included β-bisabolene (15.3%), β-pinene (8.2%), β-sesquiphellandrene (7.6%), chavicol (7.5%) and β-elemene (6.0%), while β-bisabolene (19.9%), β-sesquiphellandrene (11.3%), β-caryophyllene (8.8%) and β-elemene (4.7%) were the main components in the pseudostem. In the rhizome, 1,8-cineole (17.9%), β-bisabolene (13.9%), β-sesquiphellandrene (6.8%) and β-elemene (4.0%) were the major components. The essential oils were also subjected to antifungal and antibacterial tests, using the minimum inhibitory concentration (MIC) method. Results revealed weak inhibitions against the microorganisms tested.     

Phytochemical composition,anti-inflammatory and antitumour activities of four Teucrium essential oils from Greece

The essential oils of four Teucrium species were studied and 150 components, in all, were identified. All oils were rich in sesquiterpenes (50.1–55.8%). Spathulenol and δ-cadinene were the main compounds of Teucrium brevifolium oil; caryophyllene and 4-vinyl guaiacol predominated in Teucrium flavum. Carvacrol and caryophyllene oxide predominated in Teucrium montbretii ssp. heliotropiifolium, while carvacrol and caryophyllene were the most abundant components in Teucrium polium ssp. capitatum. The oil which most effectively inhibited LPS-induced NO production in macrophage cell line RAW 264.7 was that from T. brevifolium (IC₅₀ = 7.1 μg/ml), followed by T. montbretii ssp. heliotropiifolium and T. polium ssp. capitatum (IC₅₀ = 16.5 and 29.4 μg/ml, respectively). The in vitro cytotoxic assay on three human cancer cell lines showed that the most antiproliferative oils were those from T. polium ssp. capitatum and T. montbretii ssp. heliotropiifolium on CACO-2 cell lines (IC₅₀ = 52.7 and 92.2 μg/ml, respectively). The T. brevifolium oil showed a selective cytotoxicity on COR-L23 while significant activity was exerted by T. polium oil on C32.     

Antimicrobial activity of the essential oils of Brazilian species of the genus Cunila against foodborne pathogens and spoiling bacteria

The essential oils from aerial parts of six Brazilian species of the genus Cunila Mill. (Lamiaceae) currently used in beverages and food preparation, and in folk medicine, were obtained by steam distillation and analyzed by GC and GC/MS. The main components of the oils were: Cunila galioides citral (citral −77.9%), C. galioides menthene (mentha-trans-2,8-dienol −20.0%, limonene −13.6%, trans-ocimene −13.0%), C. incisa (1,8-cineole −42.9%, α-terpineol −14.0%), C. spicata (1,8-cineole −47.9%, α-terpineol −37.5%), C. menthoides (menthene −77.8%), C. angustifolia (sabinene −41.4%, γ-terpinene −11.4%), and C. microcephala (menthofuran −94.90%). These oils were screened for antibacterial activity against 15 bacterial species. The oil of C. galioides citral efficiently controlled the growth of Bacillus sp., L. monocytogenes, S. aureus, A. hydrophila, and E. faecalis, showing both contact and gaseous activity. Although less efficient, the other essential oils studied were effective against Bacillus species, S. aureus, and other specific bacteria. MIC and MCC values support their popular use, and indicate that they can be an efficient alternative for the control of foodborne and spoiling bacteria.     

Chemical composition and antimicrobial activity of Vitex agnus-castus L. fruits and leaves essential oils

The following study deals with the chemical composition, antimicrobial activity of essential oils of Vitex agnus-castus L. and their main constituents in vitro and in vivo. The main compounds in the oil of unripe fruits were sabinene (17.8%) and 1,8-cineole (17.5%), while in the oil of the ripe fruits dominant compounds were 1,8-cineole (16.3%) and sabinene (13.4%). The leaves oil contained an abundance of 1,8-cineole (22.0%), as well. All of the oils tested were rich sources of α-pinene (12.2%, 9.4% and 9.4%, respectively). Antimicrobial activity was tested using bacterial and fungal strains by the microdilution method. Using the same technique 1,8-cineole and α-pinene showed very high antimicrobial potency as well. As 1,8-cineole was the predominant constituent of the oils, we have chosen to test it further in an in vivo experiment. Randomly chosen apples were treated with 1,8-cineol solution and infected with Aspergillus niger in order to provoke Aspergillus rot in apples. Disease incidence was recorded.     

Chemical composition and antimicrobial activity of the essential oil of Coriandrum sativum

The essential oil from leaves of Coriandrum sativum L. (Apiaceae), obtained by hydro-distillation was analysed by gas chromatography–mass spectrometry (GC–MS) and also evaluated for in vitro antimicrobial activity. Out of 27 peaks, 24 components, which constitute 92.7%, were identified in the oil. The oil was dominated by aldehydes and alcohols which accounted for 56.1% and 46.3% of the oil, respectively. The major constituents were 2E-decenal (15.9%), decanal (14.3%), 2E-decen-1-ol (14.2%) and n-decanol (13.6%). Other constituents present in fairly good amounts are 2E-tridecen-1-al (6.75%), 2E-dodecenal (6.23%), dodecanal (4.36%), undecanol (3.37%), and undecanal (3.23%). The oil was screened for antimicrobial activity against both Gram positive (Staphylococcus aureus, Bacillus spp.) and Gram negative (Escherichia coli, Salmonella typhi, Klebsiella pneumonia, Proteus mirabilis, Pseudomonas aeruginosae) bacteria and a pathogenic fungus, Candida albicans. The oil showed pronounced antibacterial and antifungal activity against all of the microbes tested, except for P. aeruginosae, which showed resistance.     

Chemical composition and antimicrobial activity of the essential oil of Lippia grandis Schauer (Verbenaceae) from the western Amazon

Lippia grandis Schauer is an aromatic plant that has been used as a spice in Brazilian culinary and in traditional medicine to treat liver disease, disorders of the stomach and throat infections. We determined the chemical composition of the essential oil of L. grandis and evaluated its potential for the treatment of clinically-important pathogenic micro-organisms. The essential oil was obtained by hydrodistillation and analyzed by gas chromatography-mass spectrometry (GC-MS), giving carvacrol (37.12%), ρ-cymene (11.64%), and thymol (7.83%) as the main components. The agar disk diffusion method of the essential oil was effective against 75% of the micro-organisms analyzed, in particular, Staphylococcus aureus, Enterococcus faecalis, and Escherichia coli. The minimum inhibitory concentration was 0.57 mg/ml for E. faecalis and 1.15 mg/ml for all the other strains. The results indicate that the essential oil of L. grandis contains chemical compounds with good potential for the treatment of infections.     

Chemical composition,antimicrobial, cytotoxic and antioxidant activities of the essential oil of Artemisia indica Willd

Essential oil from the aerial parts of Artemisia indica was analysed by GC-FID and GC–MS. A total of 43 compounds representing 96.8% of the oil were identified and the major components were found to be artemisia ketone (42.1%), germacrene B (8.6%), borneol (6.1%) and cis-chrysanthenyl acetate (4.8%). Antimicrobial activity of the oil was evaluated against seven clinically significant bacterial and two fungal strains. The essential oil and its major constituents exhibited moderate to potent, broad-spectrum antibacterial and antifungal activities targeting both Gram-positive and Gram-negative bacteria. In vitro cytotoxicity evaluation against four human cancer cell lines THP-1 (leukemia), A-549 (lung), HEP-2 (liver) and Caco-2 (colon) showed that the essential oil exhibited concentration dependant growth inhibition in the 10–100 μg/ml dilution range, with IC₅₀ values of 10 μg/ml (THP-1), 25 μg/ml (A-549), 15.5 μg/ml (HEP-2) and 19.5 μg/ml (Caco-2). It was interesting to note that the essential oil also exhibited potent antioxidant activity.     

Chemical composition and biological activities of Algerian Thymus oils

The compositions of essential oils isolated from nine samples of three Thymus species (Thymus algeriensis, Thymus pallescens and Thymus dréatensis) were analysed by GC and GC–MS, and a total of 114 components were identified. T. pallescens collected from various regions showed a great similarity in their compositions and were characterised by carvacrol (44.4–57.7%), p-cymene (10.3–17.3%) and γ-terpinene (10.8–14.2%) as the major components for four samples; only one sample was thymol-rich (49.3%) with a small amount of carvacrol (9.0%). On the other hand, T. algeriensis showed a chemical polymorphism, even for samples from the same location, and two new chemotypes for this species were proposed. Oxygen-containing monoterpenes were the predominant class (76.3%) in T. dreatensis oil, with linalool (30.4%), thymol (20.2%) and geraniol (19.6%) as the principal constituents. The oils were screened for their possible antioxidant activities by four complementary assays, namely DPPH free radical scavenging, hydroxyl radical scavenging, inhibition of lipid peroxidation and reducing power. The two new chemotypes of T. algeriensis exhibited strong hydroxyl radical scavenging (IC₅₀ = 2.2–3.3 μg/ml), but were not or only slightly active against the other radicals and exhibited a weak reducing power. Despite their chemical similarity, T. pallescens oils sometimes produced significant differences in their antioxidant activities. The essential oils were also screened for their antimicrobial activity against five bacteria (three Gram-positive and two Gram-negative) and one yeast (Candida albicans). The tested essential oils showed antimicrobial activity against the microorganisms used, in particular against two important pathogens, C. albicans and Helicobacter pylori.     

A comparative study of tocopherols composition and antioxidant properties of in vivo and in vitro ectomycorrhizal fungi

In aerobic organisms, the free radicals are constantly being produced during the normal cellular metabolism. The antioxidant properties of many organisms and particularly of wild mushrooms with their content in antioxidant compounds such as tocopherols, can detoxify potentially damaging forms of activated oxygen. Herein, a comparative study of tocopherols composition and antioxidant properties of in vivo (fruiting bodies) and in vitro (mycelia) ectomycorrhizal fungi: Paxillus involutus and Pisolithus arhizus. Tocopherols were determined by high performance liquid chromatography (HPLC) coupled to a fluorescence detector. The antioxidant properties were studied in terms of DPPH radical-scavenging activity, reducing power and inhibition of β-carotene bleaching. Fruiting bodies revealed the highest antioxidant properties, including scavenging effects on free radicals (EC₅₀ = 0.61 and 0.56 mg/ml) and inhibition of lipid peroxidation capacity (EC₅₀ = 0.40 and 0.24 mg/ml for P. involutus and P. arhizus, respectively), than mycelia produced in vitro cultures. Nevertheless, mycelia revealed higher levels of total tocopherols than fruiting bodies, and particularly P. arhizus mycelium proved to be a powerful source of γ-tocopherol (154.39 μg/g dry weight).     

Essential oil composition,antimicrobial and antioxidant activities of Satureja cuneifolia Ten.

Satureja cuneifolia Ten. is a well-known aromatic plant which is frequently used as a spice and herbal tea in Anatolia. S. cuneifolia oil was analyzed by gas chromatography/mass spectrometry (GC/MS). The major components of S. cuneifolia oil were carvacrol (44.99%) and p-cymene (21.61%). The essential oil of S. cuneifolia exhibited antimicrobial activity against all of the tested foodborne and spoilage bacteria. The minimum inhibitory concentration (MIC) values for test bacteria which were sensitive to the essential oil of S. cuneifolia were in the range of 600–1400 μg/ml. Antioxidant activities of the essential oil and the methanolic extract from S. cuneifolia were evaluated by using DPPH radical scavenging, β-carotene–linoleic acid bleaching and metal chelating activity assays. In addition, the amounts of total phenol components in the plant methanolic extract (222.5 ± 0.5 μg/mg) and the oil (185.5 ± 0.5 μg/mg) were determined.     

Chemical composition and antifungal activity of essential oils from three Himalayan Erigeron species

Three Himalayan Erigeron (Asteraceae) species viz Erigeron mucronatus, Erigeron annuus and Erigeron karwinskianus growing in sub-alpine region revealed occurrence of isomeric polyacetylenic constituents viz., matricaria and lachnophyllum esters which accounted for 83.3%, 69.3% and 30.1% of the essential oils from these species, respectively, in addition to mono- and sesquiterpenoids as minor constituents. The antifungal activity tested by poisoned food (PF) techniques against Fusarium oxysporum, Helminthosporium maydis, Rhizoctonia solani, Alternaria solani and Sclerotinia sclerotiorum demonstrated significant inhibition of the mycelial growth of all strains (p < 0.05). The oils (500 μg/mL) showed significant antifungal effect against tested fungi in the growth inhibition range of 37.6–85.5% with respective IC₅₀ values ranging from 88.8 to 660.0 μg/mL as compared to standard fungicides (100% inhibition) with IC₅₀ value in the range of 32.2–129.4 μg/mL. Significant inhibition of spore germination was noticed for F. oxysporum, Curvularia lunata and Albugo candida which were highly susceptible to E. annuus oil with their IC₅₀ values 120.7, 253.5 and 300.4 μg/mL, respectively. Thus, the results obtained in this study demonstrate the potential of essential oils from Himalayan Erigeron species as non-toxic, eco-friendly and biodegradable natural fungicides.     

Chemical composition,antioxidant and antimicrobial activities of basil (Ocimum basilicum) essential oils depends on seasonal variations

Chemical composition, antioxidant and antimicrobial activities of the essential oils from aerial parts of basil (Ocimum basilicum L.) as affected by four seasonal, namely summer, autumn, winter and spring growing variation were investigated. The hydro-distilled essential oils content ranged from 0.5% to 0.8%, the maximum amounts were observed in winter while minimum in summer. The essential oils consisted of linalool as the most abundant component (56.7–60.6%), followed by epi-α-cadinol (8.6–11.4%), α-bergamotene (7.4–9.2%) and γ-cadinene (3.2–5.4%). Samples collected in winter were found to be richer in oxygenated monoterpenes (68.9%), while those of summer were higher in sesquiterpene hydrocarbons (24.3%). The contents of most of the chemical constituents varied significantly (p < 0.05) with different seasons. The essential oils investigated, exhibited good antioxidant activity as measurements by DPPH free radical-scavenging ability, bleaching β-carotene in linoleic acid system and inhibition of linoleic acid oxidation. Evaluation of antimicrobial activity of the essential oils and linalool, the most abundant component, against bacterial strains: Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Pasteurella multocida and pathogenic fungi Aspergillus niger, Mucor mucedo, Fusarium solani, Botryodiplodia theobromae, Rhizopus solani was assessed by disc diffusion method and measurement of determination of minimum inhibitory concentration. The results of antimicrobial assays indicated that all the tested microorganisms were affected. Both the antioxidant and antimicrobial activities of the oils varied significantly (p < 0.05), as seasons changed.     

Chemical composition,angiotensin I-converting enzyme (ACE) inhibitory,antioxidant and antimicrobial activities of the essential oil from Periploca laevigata root barks

The present study describes the chemical composition, and antimicrobial, antioxidant and angiotensin I-converting enzyme (ACE) inhibitory activities of essential oil from Periploca laevigata root barks (PLRB), an aromatic plant widely distributed in Tunisia and used as a traditional medicinal plant. Gas chromatography/mass spectrometry was used to determine the composition of the PLRB oil. Forty-three components were identified in the essential oil and the main compounds were benzaldehyde (56%), methyl 4-methoxysalicylate (6.55%) and carvacrol (4.75%). The PLRB essential oil exhibited a dose-dependent manner of inhibitory activity toward ACE. The highest ACE inhibitory activity (54%) was observed at a concentration of 30 μg/ml. The PLRB oil was also found to possess antioxidant activities, as evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical method, β-carotene bleaching and reducing power assays. The antimicrobial activity of the essential oil was also investigated on several microorganisms. The inhibition zones and minimal inhibitory concentration (MIC) values of bacterial strains were in the range of 12–46 mm and 50–300 μg/ml, respectively. The inhibitory activity of the PLRB essential oil against Gram-positive bacteria was significantly higher than against Gram-negative. It also exhibited remarkable activity against several fungal strains.