Effects of Soluble Tea Polysaccharides on Hyperglycemia in Alloxan-Diabetic Mice

The effects of tea water extracts (TWE), crude tea polysaccharides (CTP), and a tea polysaccharide fraction (TPF) were tested on hyperglycemic diabetic mice. Results indicated that TWE, CTP, and TPF could significantly decrease fasting blood glucose (FBG) and glucosylated serum protein (GSP) in alloxan-induced diabetic mice compared to the control group. In vitro antioxidant activities of TWE, CTP, and TPF for scavenging hydroxyl radicals and superoxide radicals decreased with the degree of purification and were lowest for TPF. High-performance gel permeation chromatography (HPGPC) and component analysis revealed the molecular mass distribution and constituents of TWE, CTP, and TPF, indicating that a 100−120 kDa fraction contained the hypoglycemic activity. This fraction was essentially composed of polysaccharides (∼90%) with substantial amounts of arabinogalactan proteins. The second-derivative IR spectra of TWE, CTP, and TPF with peak intensity around 1075 and 1045 cm-1, which characterize galactopyrano...