绿茶、乌龙茶、红茶的茶多糖组成、抗氧化及降血糖作用研究

目的:比较绿茶、乌龙茶、红茶的茶多糖(TPS)含量、组成、体外清除自由基以及降血糖效果。方法:选择湖北福鼎大白茶、福建水仙以及云南大叶种鲜叶,都制成绿茶、乌龙茶和红茶,提取TPS,并测定其得率,分析TPS中的中性糖、糖醛酸、蛋白质含量,观察体外清除-2O和·OH的作用以及对四氧嘧啶诱导的糖尿病小鼠的降血糖效果。结果:1. TPS得率、中性糖、糖醛酸、蛋白质含量高低依次为绿茶>乌龙茶>红茶,体外清除 -2O 和·OH 的能力大小依次为乌龙茶>绿茶>红茶。2. 在所设定的低、中、高剂量(100 mg·kg-1·d-1、300 mg·kg-1·d-1、600 mg·kg-1·d-1)下,各种茶叶TPS对DM小鼠都有显著或极显著的降血糖效果,其中在低、中等剂量下,乌龙茶、红茶TPS的降低血糖作用明显优于绿茶TPS,但在高剂量下差异不明显。3. 不同产地、品种和茶类的TPS得率、中性糖、糖醛酸、蛋白质含量高低、体外清除-2O和·OH 能力,对DM小鼠降血糖效果均不相同,其中以湖北产茶叶TPS降血糖效果最好,其次是福建茶叶,再次是云南茶叶。结论:不同产地、品种、加工工艺对茶叶的茶多糖含量、组成、体外清除自由基以及降血糖效果都有显著性影响。

STUDIES ON COMPOSITION,ANTIOXIDATION AND HYPOGLYCEMIC EFFECTS OF POLYSACCHARIDES FROM GREEN TEA, OOLONG TEA AND BLACK TEA

Objective: To compare tea polysaccharides(TPS) characteristics and their role in scavenging free radicals and reducing blood glucose(BG) in diabetic mice(DM). Methods: TPS was extracted from green,Oolong and black tea which were made from the same fresh leaves from Hubei,Fujian and Yunnan. Then the recovery rate of TPS, contents of neutral sugar, uronic acid and protein were analysed, and scavenging rate of -2Oand 稯H in vitro and hypoglycemic effect were also determined. Results: 1. The yield and contents of neutral sugar, uronic acid and protein of green tea TPS were the highest, and those of black tea TPS were the lowest. Oolong tea TPS acted the best in scavenging-2O and 稯H . 2. The hypoglycemic effect of TPS from Hubei tea was the best . The effect of TPS extracted from semi-fermented Oolong tea and fermented black tea was better than that of non-fermented green tea. 3. There were obvious differences in yield, free radical scavenging rate and effect of reducing BG among TPS extracted from tea in different regions. TPS extracted from Fujian tea had the best effect in reducing BG,but that from Yunnan tea had not. Conclusion: There was remarkable effect of region and process on physico-chemical characteristics,effect of scavenging radical and reducing blood sugar TSP.