Structure and hypoglycemic activity of a novel exopolysaccharide of Cordyceps militaris

A novel neutral exopolysaccharide (EPS-III) was isolated from culture broth of Cordyceps militaris (C. militaris). The EPS-III was a homogeneous polysaccharide with M-w of 1.56 x 10(3) kDa. The yield of EPS-III from culture broth was 123.2 +/- 3.1 mg/L. and the sugar content was 93.32 +/- 0.87%. The backbone of EPS-III was mainly consisted of -> 4)-alpha-D-Galp-(1 ->, while -> 3, 6)-alpha-D-Manp-(1 ->,-> 4)-alpha-D-Manp-(1 ->, -> 3)-beta-D-Galp-(1 -> and -> 3)-alpha-D-Glcp-(1 -> were distributed in the backbone or in the branch chains. The EPS-III had helix structure when dissolved in weak alkaline solution. It also had branched and intertwined form on the surface. The inhibition of alpha-glucosidase significantly increased as the increase of purity of exopolysaccharides. The EPS-III had effective inhibition on the alpha-glucosidase with dose-effect relationship. Besides, the results of hypoglycemic activity analysis in vivo indicated that EPS-Rican alleviate weight loss, reduce plasma glucose concentration, improve glucose tolerance, protect immune organs and repair dyslipidemia to relieve diabetes in STZ-induced diabetic mice. The manuscript first studied the hypoglycemic activity of exopolysaccharide of by C. militaris, proving and promoting the application value of culture broth. The structure characterization of EPS-III laid experimental foundations on the exploration of structure-activity relationship. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

A novel neutral exopolysaccharide (EPS-III) was isolated from Cordyceps militaris culture, with its structure and hypoglycemic activity studied in this research, proving its potential application value in lowering blood sugar and protecting immune organs.