Identification of phenolics in the fruit of emblica (Phyllanthus emblica L.) and their antioxidant activities

An activity-directed fractionation and purification process was used to identify the antioxidative components of emblica fruit. Dried fruit of emblica was extracted with methanol and then partitioned by ethyl ether, ethyl acetate, butanol and water. The ethyl acetate fraction showed the strongest 1,1-diplienyl-2-picrylhydrazyl (DPPH) radical scavenging activity among four fractions. The ethyl acetate fraction was then subjected to separation and purification using Sephadex LH-20 chromatography and reverse-phase high-performance liquid chromatography (HPLC). Six compounds were identified to be geraniin (1), quercetin 3-beta-D-glucopyranoside (2), kaempferol 3-beta-D-glucopyranoside (3), isocorilagin (4), quercetin (5), and kaempferol (6), respectively, by spectral methods, H-1 and C-13 nuclear magnetic resonance (NMR) spectroscopy, ultraviolet-visible (UV-Vis) spectrophotometry and mass spectroscopy (MS), and comparison with literatures. Compounds 2-4 and 6 were identified from emblica fruit for the first time. Furthermore, the antioxidant activities of purified compounds were screened for their antioxidative potential using lipid peroxidation and DPPH systems. All the purified compounds showed strong antioxidant and radical scavenging activities. Amongst, geraniin showed the highest antioxidant activity (4.7 and 65.7 mu M of IC50 values for DPPH and lipid peroxidation assay, respectively) than other purified compounds. (C) 2008 Elsevier Ltd. All rights reserved.