The effect of UV-C on the total antioxidant activity and phenolic content in hypericum scabroides raised under in vitro conditions

Abstract

Seeds of H. scabroides Robson and Poulter were germinated in vitro in Murashige and Skoog (MS) medium without hormones. The shoots thus obtained were then reproduced successfully in MS medium supplemented with 0.25 mg L-1 BAP (N6-benzylaminopurine). The shoots, into two groups of different periods of time (15, 30, 45, 60 min.) were exposed to UV-C as direct (covers of culture vessels are open) and indirect (covers of culture vessels are closed). After treatment, the antioxidant activities of the extracts obtained from H. scabroides were determined using the DPPH test method. The samples had lower activities than ascorbic acid (AA), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). In this work, extracts exposed for 15 min to direct UV-C had higher antioxidant activity (84.5 ± 0.4 I%) than extracts exposed for 30, 45, 60 min or control extracts (80.6 ± 0.7 I%). The results indicated that the control group extracts had a higher antioxidant activity than extracts exposed to 30, 45, 60 min or 15, 30, 45, 60 min of direct and indirect UV-C respectively. In the current study, brief UV-C exposure led to an increase in the amount of antioxidant activity of H. scabroides extracts, particularly for direct and indirect 15-min doses of UV-C. However, only the extracts exposed to15 min of direct UV-C had a higher response with respect to total phenolic content (837±2.1 μg/mg) than the control group (815±1.3 μg/mg).