Extraction and radicals scavenging activity of polysaccharides with microwave extraction from mung bean hulls

Extraction variables of microwave extraction mung polysaccharides (MEMPs) from mung bean hulls were optimized by Box-Behnken design. The optimal extraction parameter of MEMP was 700 W, 70 s and 17 mL/g, and highest recovery was 60.03±2.56 mg GE/g DW, which was agreed closely with predicted values. Two purified polysaccharide fractions (MEMP-1 and MEMP-2) were successfully isolated through DEAE cellulose-52 chromatography and Sephadex G-100 size-exclusion chromatography in steps. MEMP-1 was mainly composed of mannose and galactose while that of MEMP-2 was rhamnose and galactose. MEMP and purified fractions both had great radicals scavenging activities of hydroxyl and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, and MEMP-2 possessed highest antioxidant activity. The results suggested that MEMP-2 could be the suitable natural antioxidants and may be the functional foods for humans.