Composition and antibacterial activities of essential oils of seven Ocimum taxa

GC/MS was used to identify compounds of essential oils from seven Ocimum taxa (O. americanum L., O. basilicum L., O. campechianum Mill., O. x citriodorum Vis., O. kilimandscharicum Baker ex Gürke and three botanical varieties and cultivars of Ocimum basilicum L.: ‘Genovese’, var. difforme and var. purpurascens). Preliminary screening of their antibacterial activity was done against a number of common pathogens (Enterococcus faecalis, Enterococus faecium, Escherichia coli 0157:H7, Listeria monocytogenes, Listeria ivanovii, Proteus vulgaris, Staphylococcus aureus, Staphylococcus epidermis) using the filter paper disc agar diffusion technique, while further analyses were done by modification of the disc diffusion method. A broad variation in the antibacterial properties of investigated essential oils was observed. E. coli 0157:H7 was inhibited by O. basilicum ‘Genovese’ essential oil, while Ocimum americanum and Ocimum x citriodorum essential oils were the most effective against Enterococcus faecalis, Enterococcus faecium, P. vulgaris, S. aureus and S. epidermis.     

Chemical composition and antimicrobial activity of the essential oils of four Ocimum species growing in Tanzania

As part of ongoing research on Tanzanian plants used as edibles or spices, six samples of essential oils from four Ocimum species (O. basilicum, O. kilimandscharicum, O. lamiifolium, O. suave) were analyzed by GC and GC–MS. Eighty-one compounds, corresponding to 81.1–98.2% of the chemical components of the oils, were identified. Major compounds were either phenyl propane derivatives or terpenoids, including methyl eugenol, 1,8-cineole, camphor, bornyl acetate, germacrene-D, E-myroxide, germacrene-B, caryophylene oxide and p-cymene. The oils were also evaluated for antimicrobial activity against eight bacterial strains and three fungi. The oil of O. suave (B) showed the strongest antibacterial activity; O. suave (A), O. kilimandscharicum and, O. lamiifolium were moderately active, while O. basilicum oil was weakly active. However, none of the oils was active against the fungi species. The study has shown that, Ocimum oils could potentially be used as anti-infective agents.     

Chemical composition and biological activities of essential oil and extracts from Ocimum sanctum

The objective of the present research work was to evaluate the antioxidant, antimicrobial and antimalarial activities of essential oil and various extracts from O. sanctum. Gas chromatography-mass spectrometry analysis identified the following major compounds with their quantification as: eugenol (22.0%), β-elemene (19.2%), β-caryophyllene (19.1%), and Germacrene D (5.03%). HPLC analysis of O. sanctum extracts revealed that gallic acid, chlorogenic acid, p-hydroxy benzoic acid, caffeic acid, vanillic acid, p-coumeric acid, sinapic acid, and ferulic acid were the important phenolic acids. The methanol extract exhibited highest level of total phenolic (1.36 g/100 g dry plant material) and total flavonoid (0.67 g/100 g dry plant material) followed by ethanol and n-hexane extracts. The oil and extracts exhibited excellent free radical scavenging potential as measured by 2,2-diphenyl-1-picrylhydrazyl radical free radical-scavenging ability, and antioxidant activity as measured by inhibition of linoleic acid oxidation. Essential oil, n-hexane, methanol, and ethanol extracts exhibited moderate antimalarial potential in term of anti-haem biocrystallization activity. In the resazurin microtitre plate and disc diffusion assays, the essential oil of O. sanctum showed better antibacterial activity than various extracts. The results of the present investigation demonstrated significant (p < 0.05) variations in the antioxidant, antimicrobial, and antimalarial activities of essential oil and extracts from O. sanctum.     

Variation in the volatile terpenoids of two industrially important basil (Ocimum basilicum L.) cultivars during plant ontogeny in two different cropping seasons from India

BACKGROUND: Two Ocimum basilicum cultivars, ‘Vikarsudha’ and ‘CIM‐Saumya’, grown in the Kumaon region of western Himalaya were evaluated for their essential oil yield and composition at different stages of plant growth during two distinct cropping seasons (spring–summer and rain–autumn). RESULTS: The highest yield of essential oil was obtained at full bloom stage in both cultivars in both cropping seasons. The essential oils obtained from different stages in two cropping seasons were analysed by capillary gas chromatography with flame ionisation detection, and gas chromatography–mass spectrometry. The major component of cultivar ‘Vikarsudha’ was methyl chavicol (84.3–94.3%), while for cultivar ‘CIM‐Saumya’ the main components were methyl chavicol (62.5–77.6%) and linalool (14.4–34.1%). CONCLUSION: This study clearly indicated that cultivar, cropping season, plant ontogeny and plant part had significant effects on the yield and quality of the essential oil of O. basilicum. Further, the amount of methyl chavicol in the cultivars grown in this region was higher than in cultivars from other parts of India. Copyright © 2011 Society of Chemical Industry     

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.     

In vitro application of selected essential oils and their major components in controlling fungal pathogens of crown rot in Embul banana (Musa acuminata– AAB)

The necessity for pesticide‐free fresh produce have prompted investigating the effect of selected essential oils and their major components on inhibition of conidial germination, appressoria formation and membrane permeability changes of the pathogens responsible for crown rot of banana. Eugenol, which is the major component of the essential oil of Ocimum basilicum, was the most effective chemical component in inhibiting conidial germination of Colletotrichum musae and Fusarium proliferatumin vitro while Cymbopogon citratus oil was the least effective. Both O. basilicum and C. citratus oils and their major components (Eugenol, citral a + b) inhibited appressoria formation by C. musae and changed the selective permeability of conidial membranes. Ocimum basilicum oil, eugenol and citral a + b could be satisfactorily used for inhibition of conidial germination and disruption of conidial activity of banana pathogens.     

Composition of the essential oils from leafy parts of the shoots,flowers and fruits of Eryngium amethystinum from Amiata Mount (Tuscany,Italy)

The essential oils obtained from the leafy parts of the shoots, inflorescences and fruits of Eryngium amethystinum (Apiaceae) from Italy have been studied. The essential oil from the inflorescences was characterised by methyl-derivatives of benzaldehyde (26.4%) and by some phenylpropanoids (3.0%) such as eugenol and (E)-methyl isoeugenol. The essential oil of leafy parts of the shoots showed a higher percentage of sesquiterpenes (31.3%) than monoterpenes (20.2%). The main differences between the two essential oils can be referred to α-pinene and germacrene D: the essential oil of the inflorescences contained much more α-pinene than the other one (25.6% vs. 11.8%), while the contrary is true for germacrene D (14.5% vs. 31.3%).     

Analysis and characterization of aroma‐active compounds of Schizandra chinensis (omija) leaves

Volatile components from leaves of Schizandra chinensis (omija), a native plant of Korea, were extracted by simultaneous distillation–extraction (SDE) and analyzed by gas chromatography–mass spectrometry (GC‐MS) using two types of capillary column with different polarities (DB‐5MS and DB‐Wax). The GC‐MS analysis of volatile compounds obtained by SDE revealed that germacrene D is the most abundant compound (22.6%) in omija leaves, followed by β‐elemene (17.4%), (E)‐2‐hexenal (8.7%), and (E)‐β‐ocimene (7.2%). Aroma‐active compounds were determined by gas chromatography–olfactometry (GC‐O) using the aroma‐extract‐dilution analysis method. (E,Z)‐2,6‐Nonadienal (cucumber) was the most intense aroma‐active compound due to its higher flavor‐dilution factor (243–729) than any other compound. (Z)‐3‐Hexenal (green/apple), (E)‐2‐hexenal (green/fruity), and (E)‐β‐ocimene (wither green/grass) were also identified as important aroma‐active compounds by GC‐O. In addition, the volatile compounds were extracted by solid‐phase microextraction (SPME), and the quantitative analysis of the SPME samples gave slightly different results, depending on the type of SPME fiber, compared with those from SDE, However, the aroma‐active compounds identified in SPME were similar to those in SDE. Copyright © 2004 Society of Chemical Industry     

Evaluation of plant oils for suppression of crown rot disease and improvement of shelf life of banana (Musa spp. AAA subgroup,cv. Robusta)

Fourteen plant oils were evaluated to control the crown rot disease caused by Lasiodiplodia theobromae and Colletotrichum musae. Five of these, viz. Ocimum sanctum, Cymbopogan citratus, C. martinii, C. nardus and Pelargonium graveolens oils completely arrested the mycelial growth of both test pathogens at their lowest concentration compared to other oils. Besides, these plant oils have also inhibited the activity of cellulolytic and pectinolytic enzymes produced by these pathogens effectively under in vitro condition. The treatment of banana fruit var. Robusta (Cavendish‐AAA) with oils of O. sanctum, C. citratus, C. nardus and C. martinii not only reduced the crown rot severity significantly, but also increased the shelf life of banana fruits. However, under low‐temperature storage (14 °C) condition, O. sanctum oil increased the shelf life of banana fruits up to 48 days without affecting their organoleptic properties. Hence, O. sanctum oil could be used as an alternative to chemical fungicides for the management of crown rot disease.     

Essential oil of Teucrium scorodonia L. ssp. scorodonia from Italy

The essential oil of the flowering aerial parts of Teucrium scorodonia L. ssp. scorodonia growing in Italy on Verrucano, was analyzed by GC and GC–MS. All the identified compounds were sesquiterpene hydrocarbons. The main ones were germacrene B (26.2%) and β-caryophyllene (25.2%).     

Chemical composition of Ocimum basilicum L. essential oil and its efficacy as a preservative against fungal and aflatoxin contamination of dry fruits

The study presents fungal and aflatoxin contamination of some dry fruits and Ocimum basilicum essential oil (EO) as a plant‐based preservative. During mycoflora analysis, 2045 fungal isolates were recorded from dry fruits and 40% isolates of Aspergillus flavus were toxigenic in nature. The EO of O. basilicum exhibited strong fungitoxicity against toxigenic strain of A. flavus. Its minimum inhibitory concentration (MIC) was recorded at 1.0 μL ml^?1, and it completely inhibited aflatoxin B₁ production at 0.5 μL ml^?1. The oil exhibited broad fungitoxic spectrum and considerably reduced A. flavus isolates from dry fruits when used as fumigant in closed storage containers at 1.0 μL ml^?1. The chemical profile of the EO was standardised through GC–MS analysis. Based on antifungal potency, antiaflatoxigenicity and efficacy as fumigant during storage conditions, O. basilicum EO may be recommended as a botanical preservative for enhancing the shelf life of dry fruits and edible products during storage.     

In Vitro Determination of the Antifungal Activity of Artemisia campestris Essential Oil from Algeria

The chemical composition of the essential oil isolated from the aerial parts of Artemisia campestris from Algeria and its antifungal activity against 10 filamentous fungal strains were investigated. The A. campestris essential oil was obtained in a yield of 0.71% (v/w). The major constituents of the oil were α-pinene (18.65%), β-pinene (16.78%), β-myrcene (17.34%), and germacrene D (10.34%). Our study showed that A. campestris essential oil was a potent antifungal agent against some pathogenic fungal species. Fusarium graminearum was the most sensitive strain to A. campestris essential oil with minimal inhibitory concentration and minimal fungicidal concentration values of 1.25 µL/mL (v/v). The essential oil also exhibited a strong fungicidal activity against the tested fungi, except for Penicillium citrinum, P. viridicatum, and Aspergillus niger (MFC >20 µL/mL). Our findings suggested the application of A. campestris essential oil as a biofungicide in order to reduce the dependence on synthetic fungicides and ensure food safety and quality.     

Chemical composition and some biological activities of the volatile oils of a chemotype of Lippia chevalieri Moldenke

The volatile oils of a chemotype Lippia chevalieri collected in Burkina-Faso were obtained by hydrodistillation and analysed by GC and GC/MS. Most of the constituents identified in leaves and flowers oils were sesquiterpenoids. The dominant components in the oil from leaves were β-caryophyllene (27%), elemol (22%) and caryophyllene oxide (9%) whereas those found in the oil from flowers were β-caryophyllene (30%), germacrene d (15%) and elemol (12%). The latter compound and 1,8-cineole may be considered as metabolic markers of flowers differentiation taking into account the local environmental changes. The antibacterial and antifungal activities of both oils were tested against six microorganisms. While a strong inhibitory effect was shown regarding the growth of Staphylococcus aureus and Enterococcus hirae, a moderated effect was observed for Candida albicans and Saccharomyces cerevisiae. Elemol, 1,8-cineole, camphor and para-cymene can be considered as the principal antimicrobial components of these oils. No antioxidant capacity comparable to that of α-tocopherol was demonstrated from either oil.     

Essential oils,kava pyrones and phenolic compounds from leaves and rhizomes of Alpinia zerumbet (Pers.) B.L. Burtt. & R.M. Sm. and their antioxidant activity

During essential oil production from Alpinia zerumbet, large volumes of water and solid wastes are produced and subsequently discarded. An extraction protocol to obtain essential oil, dihydro-5,6-dehydrokawain (DDK) and enriched antioxidant phenolic extracts from fresh leaves or rhizomes of A. zerumbet and their wastes was developed. The main components determined in leaf oil were 1,8-cineol, camphor and methyl cinnamate, whereas rhizome oil mainly contained DDK and methyl cinnamate. The highest DDK content was found in the hexane extract of fresh rhizomes. Ethyl acetate extracts from leaves showed higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities than those from rhizomes. Ethyl acetate extract from wastewater of leaves possessed the strongest inhibition to β-carotene oxidation. Ferulic and p-hydroxybenzoic acids were the major phenolics present in these extracts. The results indicate that disposed wastes produced during essential oil production from A. zerumbet leaves or rhizomes may be utilized in foodstuffs as a cheap source of natural antioxidants.     

Identification of volatile components in basil (Ocimum basilicum L.) and thyme leaves (Thymus vulgaris L.) and their antioxidant properties

Aroma compounds in the extracts of basil leaves (Ocimum basilicum L.) and thyme leaves (Thymus vulgaris L.) were identified by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The major aroma constituents of basil were 3,7-dimethyl-1,6-octadien-3-ol (linalool; 3.94 mg/g), 1-methoxy-4-(2-propenyl) benzene (estragole; 2.03 mg/g), methyl cinnamate (1.28 mg/g), 4-allyl-2-methoxyphenol (eugenol; 0.896 mg/g), and 1,8-cineole (0.288 mg/g). The major aroma constituents of thyme were 2-isopropyl-5-methylphenol (thymol; 8.55 mg/g), 4-isopropyl-2-methylphenol (carvacrol; 0.681 mg/g), linalool (0.471 mg/g), α-terpineol (0.291 mg/g), and 1,8-cineole (0.245 mg/g). Twelve aroma constituents of basil and thyme were examined for their antioxidant activities using the aldehyde/carboxylic acid assay. Eugenol, thymol, carvacrol, and 4-allylphenol showed stronger antioxidant activities than did the other components tested in the assay. They all inhibited the oxidation of hexanal by almost 100% for a period of 30 days at a concentration of 5 μg/ml. Their antioxidant activities were comparable to those of the known antioxidants, α-tocopherol and butylated hydroxy toluene (BHT).     

Effect of Plant Extracts on Quality of Khasi Mandarin (Citrus reticulata Blanco) Fruits During Ambient Storage

Khasi mandarin (Citrus reticulata Blanco) fruits were treated with Azadirachta indica, Ocimum sanctum, Aloe barbedensis, carbendazim, A. barbedensis + A. indica, A. barbedensis + O. sanctum, A. barbedensis + carbendazim and control (water). Treated fruits were packed in corrugated fibre boxes and kept for a total period of 28 days at ambient storage (20?±?2 °C and 65?±?5% RH). Prominent pathogen associated with fruit rot was identified as Penicillium brevicompactum. The fruit quality during storage was evaluated in terms of disease severity (per cent disease index), inhibition of spore germination (%) of P. brevicompactum, decay loss (%), juice content retention (%), total soluble solids (%), acidity (%), ascorbic acid content (mg/100 g) and sensory scores. O. sanctum-treated fruits exhibited minimum decay loss (3.33%) up to a total period of 28 days which was even less than carbendazim (10%). O. sanctum was also highly effective in inhibiting spore germination of P. brevicompactum (96.5%). Overall acceptability score (7.33) was also high in O. sanctum-treated fruits as compared with other treatments at the end of the storage period.     

Bioactivity of Ocimum gratissimum L. oil and two of its constituents against five insect pests attacking stored food products

The fumigant and repellent effects of Ocimum gratissimum L. oil and its constituents, β-(Z)-ocimene and eugenol, were evaluated against adults of Sitophilus oryzae (L.), Tribolium castaneum (Herbst), Oryzaephilus surinamensis (L.), Rhyzopertha dominica (F.) and Callosobruchus chinensis (L.). The fumigant toxicities of the oil and two of its constituents were assessed at four rates (0, 1, 5 and10 μL/L air) in space fumigation, whereas repellence of the oil and eugenol in acetone was evaluated in choice bioassays at five rates (0, 1.0, 2.0, 3.0 and 4.0 μL oil/2 g grain). Results showed that fumigant toxicity and repellence of the oil and its constituents were significantly (P<0.0001) influenced by concentration and time after treatment. At 1 μL/L air, the oil caused 98%, 99% and 100% mortality of R. dominica, O. surinamensis and C. chinensis, respectively, 24 h after treatment, whereas eugenol achieved 79%, 61% and 100% kill of the same insects. β-(Z)-ocimene produced a weaker toxicity with 8%, 11% and 59% mortality of R. dominica, O. surinamensis and C. chinensis, respectively. Except for T. castaneum which was more tolerant, LC₅₀ values for tested insects ranged from 0.20 to 14, 0.01 to 17 and 0.80 to 23 μL/L air 24 h after treatment for O. gratissimum oil, eugenol and β-(Z)-ocimene, respectively. All test insects had percentage repellence (PR) values which ranged from 37.5% to 100% and 45% to 100% for the oil and eugenol, respectively. However, C. chinensis showed a dose-dependent decrease in PR values in the eugenol bioassay with a corresponding dose-dependent mortality on treated grains. Ocimum gratissimum oil and its constituents are potential alternatives to synthetic fumigants in the treatment of durable agricultural products. Successful adoption of plant oils in the protection of food commodities promises an eco-friendly option compatible with international biosafety regulations.     

Characterization of aromatic compounds and biological activities of essential oils from Tunisian aromatic plants

The aromatic compounds and biological activities of essential oils from six Tunisian aromatic plants including Artemisia herba-alba, Rosmarinus officinalis, Thymus capitatus, Mentha piperita, Ocimum basilicum and Artemisia absinthium were investigated. Hydro-distillation was used to extract essential oil from these plants. The identification of compounds from essential oils was performed using GC–MS analysis. Camphor (28.47%) was the major compound of A. absinthium essential oil. High contents of verbenone (20.99%) and camphor (19.72%) were found in R. officinalis. In the case of T. capitatus, carvacrol (81.09%), gamma terpinene (6.61%) and caryophyllene (4.87%) were identified as the major compounds. While eugenol (24.69%), linalool (18.00%) were characteristic compounds of O. basilicum essential oil, camphor (39.10%) and farnesol (14.25%) together with bornyl acetate (12.31%) were the main constituents of A. absinthium. These oils were also subjected to a screening for their antioxidant activity and essential oil from A. absinthium showed a greater antioxidant activity (IC₅₀?=?0.0063 mg/mL) compared to the standard Vitamin E (IC₅₀?=?0.019 mg/mL). The antibacterial activities of the oils against seven pathogenic strains, Pseudomonas aeruginosa, Bacillus cereus, Salmonella, Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus, Enterococcus faecalis and Micrococcus luteus, were tested. The highest and broadest activity was shown by M. piperita; however, Ocimum basilicum was inactive against all strains. Essential oils were also evaluated for antidiabetic and anti-acetylcholinesterase activities. The IC₅₀ values of A. herba-alba and O. basilicum against α-amylase were respectively 17.76 and 16.32 µg/mL suggesting a powerful anti-diabetic effect comparable to that of acarbose (IC₅₀?=?14.88 µg/mL). R. officinalis, M. piperita and A. absinthium exhibited an interesting acetylcholinesterase inhibition with IC₅₀ equal to 22, 24 and 58 µg/mL respectively.     

Potential of some volatile oils in protecting packages of irradiated wheat flour against Ephestia kuehniella and Tribolium castaneum

Six essential oils of Citrus reticulate (mandarin peel), Pimpinella anisum (anise), Anethum graveolens (dill), Allium sativum (garlic), Ocimum basilicum (basil) and Zingiber officinale (ginger), were evaluated for fumigant toxicity against Ephestia kuehniella and Tribolium castaneum and for contact toxicity against larvae of both species. The major compounds in these volatile oils were identified using gas chromatography- mass spectrometry. Both O. basilicum and Z. officinale oils gave 100% mortality within 24 h with doses of 32 μl/l air for E. kuehniella adults, and 128 μl/l air for T. castaneum adults. The oil of A. graveolens was the most effective against larvae of both species; treated filter papers giving 100% mortality of T. castaneum and E. kuehniella larvae with exposure periods of 24 h and 96 h, respectively. The persistence of toxicity of the six tested oils varied according to their chemical components with A. graveolens and O. basilicum proving the most persistent, and C. reticulate and P. anisum the least. The possible use of the oils applied as a 30% aqueous solution for protection of wheat flour irradiated with gamma radiation (1.5 KGy) from infestation by the test insect species during a 60-day storage period in damour and gunny plastic pouches was investigated. The effect of these oils on acetylcholinesterase activity also was examined to explore their possible mode of toxic action. Dill oil was the most active against E. kuehniella larvae while ginger oil had the greatest depressive action against T. castaneum larvae.