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PubMed1999

Comparative evaluation of the antimicrobial activities of essential oils of Artemisia afra, Pteronia incana and Rosmarinus officinalis on selected bacteria and yeast strains.

Essential oils are frequently used for flavour and fragrance in the perfume, pharmaceutical, cosmetic and food industries. The antimicrobial activities of the essential oils of Artemisia afra, Pteronia incana and Rosmarinus officinalis were tested against 41 microbial strains. The test organisms were selected on the basis of their significance as food spoilage and/or poisoning, common human and plant pathogens. The agar diffusion assay was performed using nutrient agar and antibiotic medium. All the oils tested displayed some antimicrobial activities. However, the efficiency differed and depended both on the type and concentration of the oil, as well as the test microbial strain. Artemisia afra and R. officinalis showed similar and higher antimicrobial activity than P. incana. Due to their broad antimicrobial activities, the essential oils of the above plants growing in Eastern Cape may have preservative potential for the food and cosmetic industries.

Artemisia↗
PubMed1999

Influence of organic matter, cations and surfactants on the antimicrobial activity of Melaleuca alternifolia (tea tree) oil in vitro.

The effect of some potentially interfering substances and conditions on the antimicrobial activity of Melaleuca alternifolia (tea tree) oil was investigated. Agar and broth dilution methods were used to determine minimum inhibitory and cidal concentrations of tea tree oil in the presence and absence of each potentially interfering substance. Activity was determined against Gram-positive and -negative bacteria, and Candida albicans. Minimum inhibitory or cidal concentrations differed from controls by two or more dilutions, for one or more organisms, where Tween-20, Tween-80, skim-milk powder and bovine serum albumin were assessed. These differences were not seen when assays were performed in anaerobic conditions, or in the presence of calcium and magnesium ions. The effect of organic matter on the antimicrobial activity of tea tree oil was also investigated by an organic soil neutralization test. Organisms were exposed to lethal concentrations of tea tree oil ranging from 1-10% (v/v), in the presence of 1-30% (w/v) dry bakers' yeast. After 10 min contact time, viability was determined. At > or = 1%, organic matter compromised the activity of each concentration of tea tree oil against Staphylococcus aureus and C. albicans. At 10% or more, organic matter compromised the activity of each tea tree oil concentration against Pseudomonas aeruginosa. Organic matter affected 1 and 2% tea tree oil, but not 4 and 8%, against Escherichia coli. In conclusion, organic matter and surfactants compromise the antimicrobial activity of tea tree oil, although these effects vary between organisms.

Agar↗
PubMed2001

Interactions between components of the essential oil of Melaleuca alternifolia.

AIMS: This study compared the antimicrobial activity of Melaleuca alternifolia (tea tree) oil with that of some of its components, both individually and in two-component combinations. METHODS AND RESULTS: Minimum inhibitory concentration and time-kill assays revealed that terpinen-4-ol, the principal active component of tea tree oil, was more active on its own than when present in tea tree oil. Combinations of terpinen-4-ol and either gamma-terpinene or p-cymene produced similar activities to tea tree oil. Concentration-dependent reductions in terpinen-4-ol activity and solubility also occurred in the presence of gamma-terpinene. CONCLUSION: Non-oxygenated terpenes in tea tree oil appear to reduce terpinen-4-ol efficacy by lowering its aqueous solubility. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings explain why tea tree oil can be less active in vitro than terpinen-4-ol alone and further suggest that the presence of a non-aqueous phase in tea tree oil formulations may limit the microbial availability of its active components.

Anti-Infective Agents, Local↗
PubMed1999

How big is a drop? A volumetric assay of essential oils.

There has been an increase in the use of aromatherapy in nursing, and many issues are now being raised which need addressing in order to maintain professional credibility and safe practice. These issues include: who can safely practise aromatherapy, what qualifications are required to practise, who provides indemnity, and other issues, including the safety and toxicity of essential oils. A small study was undertaken to examine the differences in drop size of bergamot essential oil. Drop size was determined by weighing different manufacturers' essential oil of bergamot and it was found that drop size did differ, resulting in unequal doses of essential oil. It is important to be aware of this, because there are implications for the size of the dose administered in an aromatherapy treatment. This paper raises the issue of standardizing the measurement of essential oils, to ensure that there are no problems regarding safety in their administration.

Analysis of Variance↗
PubMed1999

Microsatellite variation and assessment of genetic structure in tea tree (Melaleuca alternifolia-Myrtaceae).

Analysis of five microsatellite loci in 500 Melaleuca alternifolia individuals produced 98 alleles that were useful for population genetic studies. Considerable levels of observed heterozygosity were recorded (HO = 0.724), with approximately 90% of the variability being detected within populations. A low level of selfing (14%) was suggested to be the principal cause of excess homozygosity in a number of populations (overall FIS = 0.073). This study showed low levels of inbreeding in certain populations as well as a significant isolation-by-distance model. Only two groups of populations (Queensland and New South Wales) constituted different genetic provenances as a result of geographical isolation. The M. alternifolia data suggest that microsatellite loci did not always arise by a stepwise mutation process but that larger jumps in allele size may be involved in their evolution.

Australia↗
PubMed1999

In vitro susceptibility of opportunistic Fusarium spp. to essential oils.

The inhibitory effects of essential oils extracted from 10 Indian plants were evaluated against five fungi. The plants used for extraction of essential oils were six species of the genus Eucalyptus and Ocimum basilicum, Prosopis cineraria and Derris indica. The fungi used in the experiments were Fusarium solani, F. oxysporum, F. pallidoroseum, F. acuminatum and F. chlamydosporum. The susceptibility of the Fusarium species was tested by the paper disc method and the serial dilution technique. The results were compared with the inhibitory effects of miconazole on the fungi. The essential oils extracted from the Eucalyptus species markedly inhibited fungal growth. Prosopis cineraria did not show inhibiting properties. Among the fungi, F. oxysporum proved to be the most resistant species.

Antifungal Agents↗
PubMed1998

The synergistic preservative effects of the essential oils of sweet basil (Ocimum basilicum L.) against acid-tolerant food microflora.

Essential oils extracted by hydrodistillation from five different varieties of Ocimum basilicum L. plants (Anise, Bush, Cinnamon, Dark Opal and a commercial sample of dried basil) were examined for antimicrobial activity against a wide range of foodborne Gram-positive and -negative bacteria, yeasts and moulds by an agar well diffusion method. All five essential oils of basil showed antimicrobial activity against most of the organisms tested with the exception of Flavimonas oryzihabitans and Pseudomonas species. The inhibitory effect of Anise oil, in comparison with mixtures of the predominant components of pure linalool and methyl chavicol, against the acid-tolerant organisms, Lactobacillus curvatus and Saccharomyces cerevisiae, was examined in broth by an indirect impedance method. Synergistic effects between Anise oil, low pH (pH 4.2) and salt (5% NaCl) were determined. The antimicrobial effect of Anise oil was also assessed in a tomato juice medium by direct viable count, showing that the growth of Lact. curvatus and S. cerevisiae was completely inhibited by 0.1% and 1% Anise oil, respectively. The results of the current study indicate the need for further investigations to understand the antimicrobial effects of basil oils in the presence of other food ingredients and preservation parameters.

Acyclic Monoterpenes↗
PubMed2002

Preservative properties of Calamintha officinalis essential oil with and without EDTA.

AIMS: This study was focused on the preserving properties of Calamintha officinalis essential oil, a plant known for its diaphoretic, expectorant and aromatic properties. METHODS AND RESULTS: The commercial aerial parts of C. officinalis Moench were hydrodistilled and the essential oil analysed by Gas chromatography/Electron impact mass spectrometry (GC/EIMS). The inhibition efficacy of this essence, alone (0.5 and 1.0% v/v) and in combination with 2.0 mM EDTA, was assayed, in culture medium and in cetomacrogol cream, using preservative efficacy testing against standard microrganisms (E. coli ATCC 25922, Ps. aeruginosa ATCC 9027, Staph. aureus ATCC 6538P, C. albicans ATCC 10231 and A. niger ATCC 16404). C. officinalis essential oil in cetomacrogol cream with EDTA showed long-lasting antimicrobial activity, satisfying the European Pharmacopoeia Commission (E. P.) criteria. CONCLUSION: C. officinalis essential oil could have a potential for a future use as a cosmetic preservative. IMPACT OF THE STUDY: To find natural compounds with antimicrobial activity which could be alternatives to the synthetic chemical preservatives.

Aspergillus niger↗
PubMed2003

In vitro effect of essential oils from Cinnamomum aromaticum, Citrus limon and Allium sativum on two intestinal flagellates of poultry, Tetratrichomonas gallinarum and Histomonas meleagridis.

Essential oils may be effective preventive or curative treatments against several flagelated poultry parasites and may become primordial either to organic farms, or as more drugs are bannished. The anti-flagellate activity of essential oils obtained from fresh leaves of Cinnamomum aromaticum, Citrus limon pericarps and Allium sativum bulbs was investigated in vitro on Tetratrichomonas gallinarum and Histomonas meleagridis. On T. gallinarum, the minimal lethal concentration (MLC) at 24 hours was 0.25 microliter/ml for C. aromaticum oil, and 0.125 microliter/ml for C. limon and A. sativum oils. On H. meleagridis, MLC was 0.5 microliter/ml for C. aromaticum oil and 1 microliter/ml for C. limon and A. sativum oils at 24 and 48 hours. Moreover, no synergistic effects were evidenced in vitro. The essential oil constituents, based on their GC retention times have been also identified. The major component is trans-cinnamaldehyde (79%) for C. aromaticum; limonene for C. limon (71%) and diallyl tri- and disulfide (79%) for A. sativum. Even if concentration and protocol adaptations are required for successful in vivo treatments, it appears that these oils may be useful as chemotherapeutic agents against several poultry parasites.

Animals↗
PubMed2001

Essential oil composition and antimicrobial activity of three Zingiberaceae from S.Tomé e Príncipe.

The essential oil composition of three Zingiberaceae widely used as medicinal aromatic plants from S. Tomé and Príncipe: Aframomum danielli (Hook. f.) K. Schum., Curcuma longa L. and Zingiber officinale Rosc. was studied. Two samples of the essential oils from fruit of A. danielli and from rhizomes of the other two species, were obtained by hydrodistillation and analyzed by GC, GC-MS, and (13)C-NMR. The essential oil from fruits of A. danielli has been studied for the first time and was characterised by its high content of monoterpenes, with 1,8-cineole (25.5 - 34.4 %) the major constituent, followed by beta-pinene (14.1 - 15.2 %) and alpha-terpineol (9.9 - 12.1 %). Essential oils from the rhizomes of C. longa contained a lower content of ar-turmerone (4.0 - 12.8 %) than those reported in the literature for C. longa from other origins (24.7 - 31.4 %), whereas the results for Z. officinale essential oils were in accordance with the literature data. The essential oils of A. danielli and Z. officinale showed antimicrobial activity against all Gram-positive and Gram-negative bacteria tested, as well as against yeasts and filamentous fungi, using the agar diffusion method.

Anti-Bacterial Agents↗
PubMed2003

Antimicrobial activity and chemical composition of the essential oil of Lippia graveolens from Guatemala.

The composition and the antimicrobial activity of the essential oil of Lippia graveolens H.B.K. collected in Guatemala were studied. Two samples of essential oils were obtained from the aerial parts of the plant by hydrodistillation and analyzed by GC and GC-MS. The oils were characterized by their high content of monoterpenes (70.0-87.2 %). Important differences between the major constituents were found, particularly for carvacrol (0.2 vs. 44.8 %), thymol (18.1 vs. 7.4 %) and p-cymene (6.8 vs. 21.8 %). Both oils showed significant activity against all tested Gram-positive and Gram-negative bacteria, as well as against fungi. Nevertheless, the oil with the higher carvacrol content was found to be more active than the thymol type, with MICs ranging from 0.25 to 0.83 microL/mL and 0.12 to 0.27 microL/mL for bacteria and fungi, respectively.

Anti-Bacterial Agents↗
PubMed2005

Relaxant effects of the essential oil of Eucalyptus tereticornis and its main constituent 1,8-cineole on guinea-pig tracheal smooth muscle.

The effects of the essential oil of Eucalyptus tereticornis Sm. (EOET) on guinea-pig tracheal smooth muscle were investigated. EOET (10 - 1000 microg/mL) relaxed the tracheal basal tonus with an EC (50) value of 125.3 [52.2 - 300.9] microg/mL. Its maximal relaxation (40 +/- 6 %) was significantly lower than that evoked by aminophylline (209 +/- 34 %). The K (+)-(60 mM)-induced contractions were significantly reduced by both EOET (200 - 1000 microg/mL) and its main constituent 1,8-cineole (600 - 1000 microg/mL). Acetylcholine (1 microgM)-induced contractions were significantly enhanced by 1,8-cineole (10 - 1000 microg/mL). However, they were significantly enhanced and reduced by lower (200 - 400 microg/mL) and higher (800 - 1000 microg/mL) concentrations of EOET, respectively. Electrical field stimulation-induced contractions were significantly increased by EOET (100 - 600 microg/mL). In conclusion, EOET produces myorelaxant effects on guinea-pig isolated trachea, an effect that seems to result from a complex interaction between its monoterpenoid constituents.

Animals↗
PubMed1993

Anti-inflammatory activity of the essential oil of Bupleurum fruticescens.

The essential oil of Bupleurum fruticescens was investigated qualitatively and quantitatively by GC and GC-MS analyses. The anti-inflammatory activity of the whole essential oil and its major components was also investigated in the rat hindpaw edema model induced by carrageenin or by PGE1. The anti-inflammatory activity shown by the essential oil can be attributed to the two major components, alpha-pinene and beta-caryophyllene. In order to know the role of the adrenal glands in the anti-inflammatory activity exerted by the two major components of the essential oil, they were studied against the carrageenin-induced hindpaw edema in adrenolectomized rats. It is concluded that alpha-pinene needs the integrity of the adrenal glands to exert its anti-inflammatory activity, as opposed to beta-caryophyllene which was also active in adrenolectomized animals.

Animals↗
PubMed1991

Studies on the genotoxic properties of essential oils with Bacillus subtilis rec-assay and Salmonella/microsome reversion assay.

Genotoxic properties of essential oils from Anthemis nobilis L., Artemisia dracunculus L., Salvia officinalis L., Salvia sclarea L., Satureja hortensis L., Satureja montana L., Thymus capitatus L., Thymus citriodorus Schreb., Thymus vulgaris L., Citrus bergamia Risso, were studied with Bacillus subtilis rec-assay and Salmonella/microsome reversion assay. The essential oil of Artemisia dracunculus L. "Piemontese" turned out to be active in the rec-assay but not in the Salmonella test. DNA-damaging activity was demonstrated to be due to the estragol component of the oil. Advantages of the combined use of these two short-term microbial assays in genotoxic studies are discussed.

Animals↗