POLYPHENOLICS FROM FRESH LOTUS SEEDS: ENZYME-ASSISTED ETHANOL EXTRACTION OPTIMIZATION AND ITS ANTIOXIDANT ACTIVITY

摘要

In this study, enzyme-assisted ethanol extraction was applied with the aim to increase soluble polyphenolics extraction yield from fresh lotus seeds (FLS) using four factors, three levels Box-Behnken response surface design. Besides, this crude ethanol extract was further fractionated with different solvents including chloroform, ethyl acetate, n-butanol; and the total antioxidant capacity and the scavenging activities for DPPH, and superoxide anion free radicals of these fractions were measured to compare their antioxidant activities. In addition, the phenolics components in these fractions and the ethanol extract were identified by high-performance liquid chromatography (HPLC). Results showed the fresh lotus seeds extracted with papain (4mg/g) and a-amylase (60U/g) under 81.6 degrees C for 3h achieved the total polyphenolic contents of 2.57 +/- 0.07 mg/g. The ethyl acetate and n-butanol fractions showed stronger antioxidant activity and contained more polyphenolic components than other fractions. In conclusion, the total polyphenolic contents of free phenolic extracts from fresh lotus seeds were significantly increased by enzyme hydrolysis accompany with 50% ethanol extraction. Meanwhile, the different fractions of the crude extract with abundant polyphenolics exhibited stronger antioxidant activity.