Insights into the radioprotective efficacy of Pterocarpus santalinus L. aqueous extract.

In the present study, we have attempted a comprehensive assessment of the possible 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 gallic acid equivalents), flavonoids (6.616 µg/mg quercetin equivalents), and tannins (0.008 mg/L of PSAE) 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 cell death. 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 potent radioprotective formulation.

Radioprotective Properties of Pterocarpus santalinus Chloroform Extract in Murine Splenic Lymphocytes and Possible Mechanism.

Background: Pterocarpus santalinus popularly known as Red Sanders is an endemic species confined to Southern part of Eastern Ghats of India especially in Andhra Pradesh and has high demand for its economical importance for its use in treatment of human ailments. Materials and Methods: In the present study, the authors have examined the presence of various phytochemicals in the chloroform extract of P. santalinus heartwood (PSCE, Pterocarpus santalinus chloroform extract) by qualitative and quantitative assays. PSCE was further used to evaluate its antioxidant and metal reducing capacity. Radioprotective property was also evaluated in various subcellular and cellular model systems. Results: The phytochemical screening study showed that the extract was positive for carbohydrates, cardiac glycosides, flavonoids, phenols, tannins, saponins, and terpenoids and was negative for alkaloids, steroids, and phlobatannins. Contents of total phenol, total flavonoids, total anthocyanin, and total tannin in the PSCE are 404 µg/mg in terms of gallic acid equivalents, 22.6 µg/mg in terms of quercetin equivalents, 0.066 mg in terms of cyanidin-3-glucoside (cyn-3-glu) equivalents, and 12.477 g/L, respectively. This extract exhibited significant radical scavenging activity against model free radical 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS•+), 1,1-diphenyl picrylhydrazyl, and biologically important nitric oxide. It has significant metal reducing capacity as monitored by ferric and molybdenum reduction assay. PSCE showed a concentration dependent radioprotection to plasmid pBR322 DNA and lipids of the mitochondrial membranes. Their study also showed that PSCE protected splenic lymphocytes against radiation induced cell death, DNA double strand breaks, and lipid peroxidation as monitored by propidium iodide staining, γ-H2AX assay, neutral comet assay, and TBARS assay, respectively. Addition of PSCE to lymphocytes scavenged radiation derived reactive oxygen species, restored loss of thiol content, and inhibited cellular apoptosis. Conclusions: PSCE possesses high antioxidant activity and exhibited very good radioprotective property in cell free and cellular model systems.