Évaluation in vitro de l'effet des huiles essentielles de Salvia officinalis L, Laurus nobilis L et Thymus vulgaris L sur les lactobacilles du microbiote vaginal humain.

Abstract

The vaginal microbiota, dominated by bacteria of the genus Lactobacillus, is a key component of vaginal balance and protection against urogenital infections. Accordingly, essential oils are attracting growing interest due to their widely reported antimicrobial properties against pathogens. However, their selectivity towards beneficial lactobacilli flora remains insufficiently explored, whilst the absence of a selective effect could lead to an alteration of the vaginal microbiota. In this context, the present study aims to assess the safety of three essential oils (Thymus vulgaris, Salvia officinalis and Laurus nobilis) with regard to lactobacilli isolated from the vaginal microbiota, in order to evaluate their potential for safe use in gynaecological applications. Ten Lactobacillus isolates were recovered from vaginal swabs collected from ten healthy women and were identified based on their phenotypic characteristics. The essential oils were obtained by Clevenger-type hydrodistillation and steam distillation, with yields ranging from 0.65% to 2.295%. The results of in vitro susceptibility tests revealed variability in activity among the essential oils. T. vulgaris exhibited marked inhibitory activity, with an inhibition zone of 30.82 mm. In comparison, S. officinalis and L. nobilis exhibited more moderate activity, with inhibition zones of 14.30 mm and 11.70 mm respectively. The minimum inhibitory concentrations observed ranged from 0.312 μl/ml to 10 μl/ml. These results indicate that the essential oil of T. vulgaris exerts a potentially disruptive effect on the vaginal microbiota due to its pronounced inhibitory action on lactobacilli, whilst S. officinalis and L. nobilis exhibit a more moderate activity profile, suggesting better compatibility with the preservation of the protective flora. Further investigations, including molecular analyses, identification of active compounds, and in vivo and clinical studies, are necessary to confirm the efficacy and safety of essential oils in the treatment of vaginal infections while preserving the vaginal microbiota.