Chemical structure and effects of antioxidation and against α-glucosidase of natural polysaccharide from Glycyrrhiza inflata Batalin

GIBP, a homogeneous polysaccharide extracted from Glycyrrhiza inflata Batalin with a molecular weight 1.96 × 103 kDa, had a triple helix structure, smooth and sheet-like structure. Comprehensive analysis showed that the main chain of GIBP was composed of α-D-1,4 linked glucose, branch points were composed of α-D-1,3,6 and α-D-1,2,3,6 linked glucoses, and side chains were composed of α-D-1,3 and β-D-1,6 linked galactose, β-L-1,2 linked arabinose, α-D-1,3 and β-D-1,3 mannose. The scavenging abilities of GIBP (3 mg/mL) against DPPH radical, OH radical, O2− radical and ABTS were 50.75 ± 0.13% and 52.32 ± 0.13, 25.84 ± 0.35% and 44.57 ± 0.15% and it also demonstrated an obvious dose-effect relationship. The inhibitory activity of α-glucosidase showed that the inhibitory effect of GIBP was enhanced with the increase of concentration. When the concentration reached 6 mg/mL, the inhibition rate of α-glucosidase activity reached 64.77%. And the ka, kd and KD were 6.472 × 104 1/Ms., 2.934 × 10−3 1/s and 4.534 × 10−8 M.