Essential oils content, composition and antioxidant activity of lemon balm, mint and sweet basil from Serbia

Lemon balm, mint, and basil were used to determine whether light modification (plants grown under pearl shade nets with 40 % shaded index or in un-shaded open field) could improve the quantity and quality of essential oils (EOs) and antioxidant activity. The yield of EOs of lemon balm, mint and sweet basil obtained after 120 min of hydrodistillation was 0.18, 2.00, and 1.12 mL/100 g, respectively. At the same time under shading conditions plants obtained more levels of EOs (0.22, 2.23, and 1.32 mL/100 g). The main components of the lemon balm essential oil are geranial (6.84-7.78 %); neral (3.02-3.52 %) and piperitenone oxide (1.67-5.36 %). The main components of mint essential oil are piperitenone oxide (12-14 %) and 1,8 cineole (1.32-2.27 %), while basil essential oil consists of the following components: linalool (9.06-10.2 %); 1,8 cineole (1.26-8.06 %) and alpha-trans bergamotene (1.21-1.47 %). The essential oil obtained from basil leaves grown under shading has shown the highest antioxidant activity (EC50 value after 20 min of incubation = 0.68 mg/mL). Medicinal plants are a good source of natural antioxidants with potential application in the food and pharmaceutical industries. Medicinal plants can be recommended to grow in shading conditions for achieving optimal quality parameters.