ANTIMICROBIAL ACTIVITY OF ESSENTIAL OILS FROM MEDICAL PLANTS GROWN IN LIGHT MODIFIED ENVIRONMENT

Abstract

Thyme, marjoram, lemon balm, mint, and sweet basil were used to determine whether light modification (plants grown under pearl nets with 50% shaded index or un-shaded - open field conditions) could improve the antimicrobial activity of essential oils (EOs). Obtained results were discussed concerning previously determined yield and composition of EOs from five medicinal plants. Seven microorganisms were selected to determine the antimicrobial activity of medicinal plants essential oils. The inhibition zone is dependent primarily on the plant species and the influence of shading is much less expressed. The results revealed that EOs from Thymus vulgaris L., proved most active against all isolates with inhibitory zone range from 24 mm (B. subtilis) to 56 mm (C. albicans). From all species of the plants, only marjoram exhibits inhibition (18-20 mm) in the case of P. aeruginosa. EOs from shaded thyme and marjoram expressed higher inhibition effects in comparison to other shaded or unshaded plants against all tested microorganisms. EOs from all shaded plants, except basil, showed higher anti-candida activity than EOs from unshaded plants. The results of this study suggest that the natural products derived from Lamiaceae plantsmay have potential use in the food and/or pharmaceutical industries as antimicrobial agents.