Antioxidant activity of Potentilla fulgens: An alpine plant of western Himalaya

Antioxidant activities of the methanol extract, fractions and isolated compounds from the roots of Potentilla fulgens Lodd. were evaluated by three in vitro experiments, namely, ABTS, DPPH, and FRAP assays. PF-2 was characterized as a new biflavanoid and designated as Potifulgene on the basis of NMR and mass spectrum, whereas PF-1 was identified as epicatechin. The activities of aqueous methanolic extract and fractions could be correlated with their respective total phenolic content and compared with standard natural antioxidants such as quercetin, vitamin C and pyrogallol. The root powder of the plant was extracted with methanol/water (80:20) by cold extraction and its extract was further partitioned with ethyl acetate, butanol and water fractions. Among the three fractions (ethyl acetate, butanol and water fraction) and the total aqueous methanolic extract, the butanol fraction exhibited good scavenging response measured in terms of TEAC (mM Trolox equivalent/mg extract). The butanol fraction was found to possess strong antioxidant activity (2.54 ± 0.69, 2.41 ± 0.53, 3.57 ± 0.05 mM Trolox equivalent/mg extract) with ABTS, DPPH and FRAP assays, respectively. The chemical composition of extracts, studied in terms of total polyphenol content (TPC), was found in the range of 20.61 ± 0.38 to 33.28 ± 0.11 mg/g gallic acid equivalent. A significant correlation was observed between total polyphenolics and antioxidant activity, indicating participation of phenolics in antioxidant activities of extract and fractions. The antioxidant activity of new biflavanoid (Potifulgene) was found to be higher, i.e. 6.85 ± 0.38, 4.24 ± 0.41, 5.35 ± 0.53 than that of epicatechin, 2.13 ± 0.05, 1.50 ± 0.02, 1.57 ± 0.03 with ABTS, DPPH and FRAP assays.