Antioxidant properties of proanthocyanidin fraction isolated from wild grape (Vitis amurensis) peel

The proanthocyanidin fraction was isolated from the wild grape (Vitis amurensis) peel and its antioxidant capacities were examined to promote the utilization of wild grape by-products. The 70% acetone crude extract of the wild grape peel was fractionated with hexane, ethyl acetate, and water. The ethyl acetate fraction was applied to a Sephadex LH-20 column chromatograph, which was eluted with 50% methanol, 75% methanol, and 75% acetone. The proanthocyanidin characteristics and contents of the isolated fractions were investigated by the vanillin-H₂SO₄ and BuOHHCl methods. Fraction 6 had the highest proanthocyanidin content (49.35±2.75 g%) among the isolated fractions. The antioxidant activities of the proanthocyanidin fraction were examined by DPPH radical scavenging, FRAP assay, and total phenolic contents. The FRAP values and total phenolic contents of the fractions ranged from 3.54 to 32.25 mmol/kg and from 4.48 to 50.80 g/100 g, respectively. The proanthocyanidin contents was strongly correlated with DPPH radical scavenging activities, FRAP values, and total phenolic contents.