Fractionation, physicochemical characteristics and biological activities of polysaccharides from Pueraria lobata roots

In this paper, three water-soluble polysaccharides (PS-D1, PS-D2, and PS-D3) isolated and purified from Pueraria lobata roots were characterized and their biological activities were evaluated. Results showed that PS-D1 was a neutral heteropolysaccharide comprised glucose and fructose in a molar ratio of 24.4:1.0 with a weight-average molecular weight (Mw) of 62 kDa, while PS-D2 and PS-D3 were both acidic heteropolysaccharides consisting of glucose, fructose, arabinose and glucose, fructose, galactose, arabinose in a molar ratio of 54.5:1.0:1.0 and 61.0:1.0:2.7:2.4 with Mws of 159 and 385 kDa, respectively. Amongst of them, PS-D3 had the highest uronic acid content (∼12.4%), carbohydrate content (∼88.9%) and Mw. All the three polysaccharides exhibited as random coils or large aggregates in aqueous solution. In vitro antioxidant activity tests indicated that PS-D3 showed the strongest scavenging capacities on hydroxyl (79.6%) and DPPH (60%) radicals at 3.0 mg/ml, and exhibited the highest antioxidant activity with a Trolox equivalent antioxidant capacity of 53.8 µmol Trolox/g and a ferric reducing ability of plasma of 56.9 µmol Fe2+/g. Moreover, the inhibitory activity on advanced glycation end-products (AGEs) formation of PS-D3 was 59.1% at 0.8 mg/ml. These results indicated that PS-D3 with prominent antioxidant capability showed pronounced non-enzymatic glycation inhibition activity in vitro.