Influence of phytochemical composition on in vitro antioxidant and reducing activities of Indian ginseng [Withania somnifera (L.) Dunal] root extracts

BACKGROUND: Roots of Withania somnifera (WS) are a celebrated medicinal ingredient in Ayurvedic and many other indigenous systems of medicine. The present study investigates the effect of the phytochemical composition of the extracts on their antioxidant and reducing activities. METHODS: WS roots were extracted with water, acetone, aqueous methanol (1:1), and methanol:chloroform:water (1:1:1) to obtain aqueous, acetone, hydro-methanolic, and methanol–chloroform–water extracts. Thereafter, phytochemical constitution and antioxidant and reducing activities of the extracts were compared using different qualitative and quantitative tests. RESULTS: Maximum extraction recovery was obtained with 50% aqueous methanol whereas extraction with acetone yielded the poorest recovery. Methanol–chloroform–water extract had the highest content of phytochemical constituents, except tannins, and also exhibited the highest antioxidant and reducing activities. CONCLUSION: Phytochemical composition and antioxidant and reducing activities of the extracts were positively associated with the use of organic solvents during the extraction process. Alkaloids and flavonoids were the most important contributors in the antioxidant and reducing activities of the extracts.