Optimization of Ultrasound-Assisted Extraction of Polyphenols from Xanthoceras sorbifolia Husks and their Determination using HPLC

X. sorbifolia can be used as both food material and medicinal plant. In this study, ultrasound-assisted extraction (UAE) was firstly used to optimize the extraction process of total polyphenols from X. sorbifolia husks. Ultrasonic time, ultrasonic temperature, ratio of solvent to material and volume fraction of ethanol were investigated and optimized by orthogonal experiments. Then, High Performance Liquid Chromatography (HPLC) was applied to analyze the polyphenols of the extract under the optimal extraction process. The optimized results for UAE was 40 min of ultrasonic time, 40 ℃ of ultrasonic temperature, 100:1 mL/g of solvent to material ratio and 60% aqueous ethanol. Under the optimal extraction process, the total polyphenol content (TPC) of the extract was 23.16 mg GAE/g DW. Furthermore, the most abundant polyphenols in X. sorbifolia husks extract, such as gallic acid, protocatechuic acid, epicatechin, myricetin-3-O-β-D-rutinoside, rutin and quercetin, were analysed using HPLC. In addition, UAE extract showed antioxidant activity in a concentration-dependent manner. Accordingly, X. sorbifolia husks can be used as a rich source of natural antioxidants. To sum up, these results provided a solid chemical basis underlying the future research and application of Xanthoceras sorbifolia husks.