ASSESSMENT OF ANTIBACTERIAL AND CYTOTOXIC PROPERTIES FOR THYMUS VULGARIS, SALVIA OFFICINALIS, MENTHA PIPERITA, ROSMARINUS OFFICINALIS, LAVANDULA ANGUSTIFOLIA AND MELLISA OFFICINALIS EXTRACTS

A multitude of phytopharmacological studies have pointed out the extraordinary biological potential owned by some herbal extracts (Ncube et al.; 2008). To establish the delimitations for their therapeutical use; the cytotoxic effect must be also taken into consideration (Gerald Muller and Axel Kramer; 2008). The aim of present research was to assess both the antimicrobial and cytotoxic properties of essential oils obtained from Thymus vulgaris; Salvia officinalis; Mentha piperita; Rosmarinus officinalis; Lavandula angustifolia and Mellisa officinalis. By determing the antibacterial activity (broth microdilution method) against the reference strain Staphylococcus aureus ATCC 25923 and; in parallel; the cytotoxicity on cultured canine leukocytes (viable cells count using Trypan Blue exclusion test); the biocompatibility index (BI) was established for each tested herbal extract. BI was defined as the ratio of the concentration at which 50% of the canine leucocytes were damaged and the minimum bactericidal concentration (MBC). All herbal extracts displayed antibacterial potential; but also some of them proved to be highly cytotoxic to the canine leukocytes as a significant decrease in the final number of viable cells was observed. Still; in case of Mellisa officinalis and Rosmarinus officinalis essential oils; the cytotoxic effect was absent for all the tested concentrations; indicating that these two essential oils could be used for their antimicrobial activity. However; further tests should be performed on their efficacy and side effects.