Ultrasound-assisted aqueous two-phase extraction of resveratrol from the enzymatic hydrolysates of Polygonum cuspidatum

An efficient ultrasound-assisted aqueous two-phase extraction (UAATPE) and enrichment process for resveratrol from the enzymatic hydrolysates of Polygonum cuspidatum using an ethanol/ammonium sulfate system was developed. After enzymatic hydrolysis using polydatin-beta-glucosidase (PBG) which was a wild extracellular enzyme, 99.7% of polydatin was converted to resveratrol. The maximum yield of resveratrol was 10.7 mg/g and the corresponding recovery rate was 99.1% at 21% (w/w) ethanol/22% (w/w) (NH4)(2)SO4. The extraction yield of resveratrol in UAATPE was increased by 43.6 and 79.4% compared with ultrasound-assisted extraction and solvent extraction with stirring, respectively. Meanwhile, the total sugars in UAATPE were only 46.8% of ultrasound-assisted extraction and 56.0% of solvent extraction with stirring. The process of UAATPE is a promising technique for extraction and enrichment of bioactive components.