Optimization for the extraction of polyphenols from Inonotus obliquus and its antioxidation activity

In order to study the extraction process and antioxidative activity of Inonotus obliquus polyphenols (IOP), the optimal extraction process was determined by orthogonal experiment optimization. The clearance rate of DPPH and hydroxyl radicals were used as indicators to evaluate the antioxidant activity of IOP. The results showed that the optimum extraction conditions were as follows: ethanol concentration of 50%, solid–liquid ratio of 1:20, temperature of 60 °C, and 90 min. Under these conditions, the extraction yield of IOP was 2.84%. The antioxidant capacity of extracts appeared to be IOP dose-dependent, while it also presented stronger ferric reducing antioxidant power (FRAP). High Performance Liquid Chromatography (HPLC-MS) analysis indicated that the major identified polyphenol compounds extracted at the optimal conditions were ten compounds (procyanidin, caffeic acid, p-coumaric acid, isorhamnetin-3-O-glucoside, astilbin, tangeretin, gallic acid, kaempferol, quercetin, and catechin 7-xyloside). These findings indicate that I. obliquus polyphenols have the potential to be developed as a natural antioxidant and have a good application prospect.