Antioxidant activities of water-soluble polysaccharide extracted from mung bean (Vigna radiata L.) hull with ultrasonic assisted treatment

Ultrasonic assisted extraction and antioxidant activity of water-soluble polysaccharide (MSP) from mung bean (Vigna radiata L.) hull were investigated. After deproteinization, MSP was isolated and purified by a DEAE-cellulose anion-exchange column and a Sephadex G-100 gel-permeation column. Two acid polysaccharide fractions, MP1 and MP2, were characterized by FT-IR, GC, and gel-permeation chromatography (GPC). Results indicated that MP1 and MP2 were acid heteropolysaccharide with 9.9% and 36.4% of uronic acid contents respectively. The main composition of MP1 was mannose, whereas MP2 consisted of rhamnose and galactose. The molecule weights of MP1 and MP2 were 83 kDa and 45 kDa, respectively. Although, MP2 showed higher hydroxyl radical-scavenging activity, MP1 exhibited higher reducing power and stronger scavenging capacity for superoxide radical and DPPH radicals as well as higher inhibition on self-oxidation of 1,2,3-phentriol than that of MP2. Thus, MP1 should be explored as a potential antioxidant.