title: Physicochemical properties and antioxidant capacity of 3 polysaccharides from green tea, oolong tea, and black tea.
abstract: Three polysaccharide-rich fractions named GTPS, OTPS, and BTPS were isolated from green tea, oolong tea, and black tea, respectively. Chemical characteristics, glycosidase inhibitory effects, and antioxidant properties of the 3 fractions were compared. Monosaccharides of GTPS were composed of D-rhamnose, L-arabinose, D-xylose, D-mannose, D-galactose, and D-glucose. But there were no xylose and mannose detected in OTPS and BTPS. The molecular weight distributions were decreased from 9.2 to 251.5 KDa to 3.8 to 32.7 KDa with the fermentation of the tea from green tea to black tea. BTPS showed the highest alpha-glucosidase inhibitory activity, antioxidant activities on hydroxyl radicals and DPPH radicals. The differences in antioxidant activities and glycosidase inhibitory properties among the 3 polysaccharide-rich fractions appeared to be related to differences in monosaccharide composition and molecular weight distribution of the polysaccharide.
  
  
  CONCLUSIONS
  Diabetes mellitus (DM) is one of the primary threats to human health due to its increasing prevalence, chronic course, and disabling complications. Control of postprandial hyperglycemia and inhibition of oxidative stress are suggested to be important in the treatment of diabetes. Many efforts had been made to search for effective and safe alpha-glucosidase inhibitors and antioxidants from natural materials to develop a physiological functional food or lead compounds for curing diabetes. Coarse tea was used to cure diabetics in people in China and Japan. The hypoglycemic activity increased with the contents of polysaccharide in coarse tea. Many studies have focused on the hypoglycemic activities of tea polysaccharides, but little is known about the glycosidase inhibitory effects of tea polysaccharide. The aim of this study was to find a tea polysaccharide with the best potential for exploitation in curing diabetes.
authors.affiliation: Tianjin Key Laboratory for Modern Drug Delivery & High-Efficiency, School of Pharmaceutical Science and Technology, Tianjin Univ., Tianjin, 300072, P.R. China. chennhxx@yahoo.com.cn
authors.forename: Haixia
authors.initials: H
authors.lastname: Chen
authors.forename: Zhishuang
authors.initials: Z
authors.lastname: Qu
authors.forename: Lingling
authors.initials: L
authors.lastname: Fu
authors.forename: Peng
authors.initials: P
authors.lastname: Dong
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000975:Antioxidants / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D002845:Chromatography; D019422:Dietary Sucrose / Q000032:analysis; D016166:Free Radical Scavengers / Q000737:chemistry; D006026:Glycoside Hydrolases / Q000037:antagonists & inhibitors*; D017665:Hydroxyl Radical / Q000737:chemistry; D007004:Hypoglycemic Agents / Q000737:chemistry; D015227:Lipid Peroxidation / Q000187:drug effects; D010434:Pepsin A / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry / Q000378:metabolism; D010940:Plant Proteins / Q000032:analysis; D011134:Polysaccharides / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D029701:Saccharomyces cerevisiae Proteins / Q000037:antagonists & inhibitors; D013045:Species Specificity; D013662:Tea / Q000737:chemistry*; D014574:Uronic Acids / Q000032:analysis
chemical_list: D000975:Antioxidants; D019422:Dietary Sucrose; D016166:Free Radical Scavengers; D007004:Hypoglycemic Agents; D010936:Plant Extracts; D010940:Plant Proteins; D011134:Polysaccharides; D029701:Saccharomyces cerevisiae Proteins; D013662:Tea; D014574:Uronic Acids; D017665:Hydroxyl Radical; D006026:Glycoside Hydrolases; D010434:Pepsin A