Abstract: Three extraction methods (heat, ultrasound-assisted, microwave-assisted) and four different solvents (water, ethanol, methanol and acetone) were used to compare the extraction efficiencies of polyphenols from leaf tissues of Rhus chinensis Mill. The thermal extraction and ethanol solvent was chosen as the basic method for further study. By using single factor test and orthogonal test, the optimized extraction conditions were as follows: solid-liquid ratio 1:15, extraction time 60 min, extraction temperature 60 ℃ and 60% ethanol solvent. Crude polyphenol powder was obtained from solution of direct centrifugation, ethyl acetate phase or water part after ethyl acetate extraction. The polyphenol purity was determined as 37.53% by direct dry, 19.26% in water phase, 59.44% in ethyl acetate phase. Their radical-scavenging activities in vitro were slight lower than to commercial tea polyphenol with 98% purity, but more than that of Vc.

Key words: Rhus chinensis Mill, polyphenols, orthogonal tests, antioxidant