Abstract
Recently, the interest in discovering natural antioxidants has increased tremendously for their application to control onset of multiple diseases. The present study was designed to determine polyphenolic compounds and antioxidant potential of Hedera nepalensis. Crude extract of H. nepalensis and its fractions (n-hexane, ethyl acetate and aqueous) was prepared by solvent–solvent extraction. Total flavonoid and phenolic contents were determined by colorimetric methods using quercetin and gallic acid as standard. Further quantitative analysis of phenolic and flavonoid compounds was carried out by using high performance liquid chromatography coupled with diode array detector (HPLC-DAD). Ethyl acetate fraction showed the highest amount of total flavonoid (2.4±0.164mgQE/100mg) and phenolic contents (12.90±0.15mgGAE/100mg). Using HPLC-DAD, catechin was identified in aqueous fraction and caffeic acid was identified in ethyl acetate fraction of H. nepalensis. The antioxidant capacity of H. nepalensis was evaluated by measuring the scavenging potential of hydrogen peroxide (H2O2), total antioxidant capacity and reducing power. The extract/fractions showed significant (P<0.05) hydrogen peroxide scavenging potential with their IC50 values ranging from 31.19 to 200μg/ml. Among crude extract and all the fractions of H. nepalensis, ethyl acetate fraction showed the highest total antioxidant activity by phosphomolybdenum method followed by n-hexane, crude extract and aqueous fraction. Moreover, ethyl acetate fraction has shown the highest reducing power followed by aqueous fraction, n-hexane fraction and crude extract. The present study provides evidence that ethyl acetate fraction of H. nepalensis has significant antioxidant potential which correlates well with its high phenolic and flavonoid contents. To the best of our knowledge catechin and caffeic acid have been reported for the first time in H. nepalensis.