Two water-soluble polysaccharides from mung bean skin: Physicochemical characterization, antioxidant and antibacterial activities

Two water-soluble polysaccharides were extracted and purified from mung bean (Vigna radiate) skin by cellulose-enzyme assisted extraction (MBP-1) and hot-water extraction (MBP-2), respectively. The physicochemical properties, antioxidant and antibacterial activities of MBP-1 and MBP-2 were investigated and compared. Results showed that MBP-1 and MBP-2 had different sugar, protein, and uronic acid contents. MBP-1 was consisted of rhamnose (Rha), arabinose (Ara), galactose (Gal), glucose (Glc), xylose (Xyl), mannose (Man), and galacturonic acid (Gal Lambda), MBP-2 was mainly composed of Rha, Ara, Gal, Glc, Xyl, fructose (Fru), and Gal Lambda, and with molecular weights (Mws) of 139 and 208 kDa, respectively. Thermal gravimetric analysis (TGA) suggested that MBP-2 had more a stable structure than MBP-1. Antioxidant assay showed that they all exhibited strong DPPH center dot,center dot OH and ABTS(+)center dot radicals scavenging abilities. MBP-1 and MBP-2 also exhibited moderate antibacterial activities against both Gram-positive (G(+)) and Gram-negative (G(-)) bacteria.