Inhibition on α-Amylase and α-Glucosidase of Polysaccharides from Inonotus obliquus and Effects on Delaying the Digestion of Polysaccharides-Dough system

In the present study, three alcohol precipitation polysaccharides fractions (IOP40, IOP60, and IOP80) are isolated from Inonotus obliquus polysaccharides (IOP). In vitro starch digestion experiments suggest that IOP40 and IOP60 show stronger inhibitory effects than crude polysaccharides. Inhibition kinetics demonstrates that IOP60 has reversible and anti-competitive inhibitory effect on alpha-glucosidase. I. obliquus polysaccharides also have a significantly effect on the digestion of dough. Furthermore, in vivo studies prove IOP60 can inhibit the increase in postprandial blood glucose level. IOP60 is further purified to gain IOP-2S. The results of monosaccharide composition show that IOP-2S consisted of mannose, rhamnose, glucose, galactose, xylose, and arabinose in Moorbys of 0.521:0.511:1.551:0.793:0.567:0.232. IOP-2S's molecular weight is 26.76 kDa. Congo red results reveal that IOP-2S contains a triple helix structure. This study indicates that I. obliquus polysaccharides might be used in functional foods for postprandial hyperglycemia control.

Automated summary

In this study, three alcohol precipitation polysaccharides fractions (IOP40, IOP60, and IOP80) were isolated from Inonotus obliquus polysaccharides (IOP). In vitro starch digestion experiments showed that IOP40 and IOP60 had stronger inhibitory effects compared to crude polysaccharides. Inhibition kinetics revealed that IOP60 had a reversible and anti-competitive inhibitory effect on alpha-glucosidase. In vivo studies confirmed that IOP60 could inhibit the increase in postprandial blood glucose level. Further purification of IOP60 resulted in IOP-2S, which showed a triple helix structure. The findings suggest that I. obliquus polysaccharides may be used in functional foods for postprandial hyperglycemia control.