Preparation and inhibition on α-D-glucosidase of low molecular weight polysaccharide from Cordyceps militaris

The structural properties and the inhibition on alpha-D-glucosidase activity of the low molecular weight (LCMPs-II) obtained from the optimized acid hydrolysis of the Cordyceps militaris polysaccharides (CMPs) were investigated in this paper. The LCMPs-II with a molecular weight of 28 KDa mainly composed of rhamnose, xylose and glucose with the molar ratio of 1: 2.19: 6.73 was separated from LCMPs-I which was the acid hydrolysis product of CMPs by chromatography on Sephadex G-100 column. The solubility of LCMPs-II was tested to be 32.12 +/- 1.05 gin 100 mL distilled water under 25 degrees C. Its solubility was almost as twice as that of CMPs. Afterward, the structural features of LCMPs-II was investigated by a combination of chemical and instrumental analysis such as the specific rotation determination, FT-IR, periodate oxidation-Smith degradation, Congo-red, GC, scanning electron microscope and NMR. The results showed that the optical rotation of LCMPs-II was +25 degrees and it was 1,3-branched-rhamnoxyloglucan which had a linear backbone of (1 -> 4)-linked alpha-D-glucopyranose (alpha-D-Glcp units). (C) 2016 Elsevier B.V. All rights reserved.