Insights into the synergistic radioprotection by secondary metabolites of Pterocarpus santalinus L. aqueous extract

Abstract Radioprotective mechanism of chloroform and hydroalcoholic extracts of Pterocarpus santalinus on spleen lymphocytes and sub-cellular systems were previously studied. In the present study, we have attempted a comprehensive assessment of the synergistic radioprotective efficacy of Pterocarpus santalinus aqueous extract (PSAE). All the studied models were gamma-irradiated with prior treatment with PSAE. First, the content of total phenols (4.061 µg mg− 1 Gallic acid equivalents), flavonoids (6.616 µg mg− 1 Quercetin equivalents), and anthocyanins (0.008 mg Cyn3-glu/g) were determined spectrophotometrically. Second, UHPLC-HRMS analysis was performed to identify the possible radioprotectors. Of those, Santalins A & B are known for their usage as natural color in foods and alcoholic beverages identified in PSAE. Treatment was well tolerated with no side effects from PSAE. Later, it was shown that radiation-induced lethality significantly amended in PSAE-treated spleen lymphocytes as evidenced by reduced elevated levels of ROS and lipid peroxidation, restored total thiols and GSH: GSSG, inhibited DNA DSBs and apoptosis. Furthermore, an immunomodulation study was carried out, because radiation exposure induces an inflammatory response. Our study shows that PSAE suppressed concanavalin A-induced T-cell proliferation as evidenced by CFSE dye dilution and CD69 antibody staining methods. Taken together, the current study explored the protective efficacy of PSAE from gamma radiation-inflicted injuries and hence we recommend PSAE as a synergistic radioprotective formulation.