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.
Keywords: antioxidant; flavonoid; free radical; gallic acid; polyphenols; radical scavenging.