Abstract
In situations of medical and occupational exposure, the radiological protection can be planned in advance. One possible method for protection, typically for dermal tissues, is a topical application of a kind of sunscreen which contains radioprotective agent with less adverse effects. Here we examined the radioprotective effects of five different natural plant-derived antioxidants, Caffeic acid (CA), Rosmarinic acid (RA), trans-Cinnamic acid (TCA), Hydroxy phenyllactic acid (HPA) and p-Coumaric acid (PCA) on cultured human keratinocytes (HaCaT). Among the compounds, the pretreatment of cells with CA, RA and TCA at the doses showing no cytotoxity (0.1-10μg/ml) resulted in approximately 10% recovery of clonogenic survival following gamma-ray exposure from Cs-137 source at 4Gy and 8Gy (1Gy/min). In addition to the intracellular antioxidative effect of these compounds against radiation-induced ROS generation as revealed by using CM-H2DCFDA as an ROS indicator, the reduction of DNA double strand break by these compounds was also observed at 15min and 6h following the irradiation by immunofluorescent detection of gamma-H2A.X and 53BP1. These findings suggest that natural antioxidants CA, RA and TCA are the candidate ingredients of radioprotective agents through the mechanisms involving the inhibition of ROS generation as expected, and possibly, the promotion of DNA damage repair.
