Alternative treatment of vaginal infections ­ in vitro antimicrobial and toxic effects of Coriandrum sativum L. and Thymus vulgaris L. essential oils.

AIMS: The aims of study were to examine the antibacterial potential of two commercial essential oils (EOs) from coriander (Coriandrum sativum L.) and thyme (Thymus vulgaris L.) against vaginal clinical strains of bacteria and yeast and their chemical composition. METHODS AND RESULTS: Antimicrobial activities of commercial essential oils were determined using macro-diffusion (disc, well) and micro-dilution method in 96-well micro plates against twelve clinical strains of bacteria: Escherichia coli, Proteus mirabilis, Staphylococcus aureus and Enterococcus sp., Staph. aureus ATCC 25923, ATCC 6538 and E. coli 25922 and two clinical Candida albicans strains, including ATTC 10231. Spectrophotometric method was used for determination on C. albicans growth. An antimicrobial effect of EOs was strain specific. Bactericidal activity was higher for coriander EO (minimal inhibitory concentration (MICs) 0·4-45·4 µl ml(-1)) against almost all tested bacteria, except multiple resistant strains of Eneterococcus sp. and Proteus sp. Thyme EO showed slightly better fungicidal activity reaching MIC at 0·11 mg ml(-1) for all C. albicans strains. The effect of EOs on biofilm-forming ability was tested for two strains of Staph. aureus and E. coli, as well as on C. albicans filamentation ability. Brine shrimp lethality bioassay revealed thymus oil total toxicity and coriander oil intoxicity (LC50 = 2·25 mg ml(-1)). The chemical composition of oils was analysed by gas chromatography mass spectrometry showing oxygenated monoterepenes as dominant constituents. CONCLUSIONS: The results provide in-vitro scientific support for the safety possible use of Coriander EO against E. coli, Staph. aureus and C. albicans vaginal infections in alternative gynaecological treatment. SIGNIFICANCE AND IMPACT OF STUDY: To examine EOs as possible constituent of naturally based antimicrobial agents in vaginaletes for safety gynaecological application.

Mentha L. species (Lamiaceae) as promising sources of bioactive secondary metabolites.

The use of mint species in traditional and conventional medicine is mostly due to the presence of two classes of secondary bimolecules: monoterpenoids in essential oils and different structural types of phenolic compounds. Essential oils are known to act as antimicrobial, antispasmodic, carminative, and antiviral agents. In addition, essential oils of several mint species have been recently qualified as natural antioxidants. However, since oil composition is highly variable, the pharmacological activity strongly depends on certain chemorace. On the contrary, composition of phenolic constituents is relatively stable within species. The most important phenolic compounds in Mentha species are flavonoids. Mints are characterized by the presence of specific lipophilic flavonoids. Phenolic compounds of mints are found to poses a wide range of pharmacological activity: antioxidant, antiulcer, cytoprotective, heptoprotective, cholagogue, chemopreventive, anti-inflammatory, antidiabetogenic etc. However, besides healing properties some mint species can exhibit an adverse effect on human health. Here we report on botany, chemistry and activity of Mentha species with special respect to their significance for the modern phytotherapy.