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.
