Structural characterization of polysaccharide from Centipeda minima and its hypoglycemic activity through alleviating insulin resistance of hepatic HepG2 cells

A novel polysaccharide (CMP-2B) was purified from Centipeda minima by anion-exchange and gel-permeation chromatography. Structural characterization revealed that CMP-2B was a homogeneous heteropolysaccharide with an average molecular weight of 113.193 KDa. CMP-2B was made up of mannose, galacturonic acid, galactose and arabinose with a molar ratio of 0.27:0.12:0.42:0.17. The backbone chain of CMP-2B consisted of 3,6)-alpha-D-Manp-(1 and 4,6)-beta-D-Galp-(1, and the branches were comprised of 4)-alpha-D-GalpA-(1, 6)-beta-D-Galp-(1, T alpha-L-Araf-(1 and 3)-alpha-L-Araf -(1. Besides, the results of antioxidant assays revealed that CMP-2B possessed signifcant free radical scavenging ability. Moreover, the results of hypoglycemic assays showed that CMP-2B displayed alpha-glucosidase inhibitory activities, and could significantly improve glucose consumption, glycogen synthesis and the activity of pyruvate kinase of insulin-resistance HepG2 cells. Overall, these results suggested that CMP-2B could be a new source for functional foods.