In-Vitro Studies on the Antioxidant Assay Profiling of Root of Withania somnifera L. (Ashwagandha) Dunal: Part 2

The anti-oxidative activities of six different extracts of Withania somnifera (Ashwagandha) root, prepared in a sequential manner starting from non-polar (hexane) to polar (water) solvent, were investigated employing various established in-vitro systems that include total antioxidant activity (TAA), total reducing power (TRP), nitric oxide scavenging activity (NOSA) and lipid peroxidation inhibition activity (LPIA). Among all the extracts, methanol extract was found the most potent and additionally, its DNA damage protective efficacy was tested using pRSET-A vector system. Positive correlations were established between total polyphenolic contents (TPC) and various activities strongly suggesting that the observed activities of the extracts may be ascribed to their phenolic compounds that could be responsible, at least partly, for the observed antioxidant activities. Six main compounds viz. alkaloids, hydroxybenzene, terpene ansteroid, saponin, organic acids and flavone were identified in methanol extract using thin layer chromatography (TLC) while by employing reverse-phase high pressure liquid chromatography (RP-HPLC) four polyphenols namely epicatechin (3.21 μg/g), quercetin-3-rhamnoside (1.12 μg/g), gallic acid (0.05 μg/g) and rutin hydrate (0.01 μg/g) were identified and quantified in aforementioned extract. Overall, the results of study clearly demonstrated that methanolic extract of Ashwagandha root possesses a marked antioxidant activity.