The impact of UV-B radiation on antioxidant activity, essential oil composition and physiological factors of Pelargonium graveolens L’Hér.

Abstract

<em>Pelargonium graveolens</em> L’Hér. is an important aromatic and medicinal plant, which is famous for its essential oils (EOS).The aim of this study was to evaluate the effects of UV-B on growth factors, essential oils components, antioxidant activity of essential oils and antioxidant enzymes activity, carbohydrate content, leaf pigments and total protein. Cuttings from potted plants were exposed to 0, 0.12, 0.26, and 0.38 W m-2 of UV-B radiation. The antioxidant enzyme activity, carbohydrate content and protein and pigments contents were measured by spectrophotometric methods. The composition of EOS was analyzed by GC-MS. The antioxidant activity of the EOS was analyzed by free radical scavenging activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH). Results demonstrated that the leaves’ fresh and dry mass, plant height, number of leaves, and the content of chlorophyll, protein and total carbohydrates were significantly (P ≤ 0.05) decreased, when plants were subjected to increased intensity of UV radiation. In contrast, the content of carotenoids and antioxidant enzymes activities increased. The chemical composition of EOS indicated that the main components in all treated plants were citronellol, geraniol, and citronellyl formate. The antioxidant activity of the essential oils increased with increasing UV-B radiation. The maximum and minimum IC50 values of essential oils were obtained in control plants and plants under 0.38 W m-2 UV-B radiation, respectively.