Objectives: The present study was to evaluate the effect of theaflavin on the activities of key enzymes of carbohydrate metabolism in high fat diet and streptozotocin – induced diabetic rats.

Methods: Diabetes was induced in male albino Wistar rats by feeding them with high fat diet comprising of standard laboratory rat chow 84.3%, lard 5%, egg yolk powder 10%, cholesterol 0.2% and bile salt 0.5% for 2 weeks. After 2 weeks, the animals were kept in an overnight fast and injected with low dose of streptozotocin (40 mg/kg b.w).

Results: Theaflavin (100 mg/kg b.w /day) was administered orally to diabetic rats for 30 days. At the end of the experimental period, diabetic control rats showed significant increase in plasma glucose, homeostatic model assessment of insulin resistance (HOMA-IR), glycosylated hemoglobin (HbA1c) with concomitant decrease in plasma insulin, total hemoglobin and body weight. The activities of key enzymes of carbohydrate metabolism, lipid peroxidation markers, antioxidant enzymes, glycogen content and glycogen synthase and glycogen phosphorylase were also altered in diabetic rats.

Discussion: Oral administration of theaflavin to diabetic rats significantly ameliorated all the biochemical alterations to near normal levels. The results of the present study suggest that theaflavin exhibits antidiabetic effect through its antioxidant activity.

目的：本研究旨在评估茶黄素对高脂饮食和链脲佐菌素诱导的糖尿病大鼠糖代谢关键酶活性的影响。

方法：在雄性白化Wistar大鼠中饲喂高脂饮食，持续2周，该饮食由标准实验鼠84.3％，猪油5％，蛋黄粉10％，胆固醇0.2％和胆汁盐0.5％组成。2周后，将动物禁食过夜，并注射低剂量的链脲佐菌素（40 mg / kg bw）。

结果：茶黄素（100毫克/千克体重/天）经口服给予糖尿病大鼠30天。在实验期结束时，糖尿病对照组大鼠的血浆葡萄糖显着增加，胰岛素抵抗的稳态模型评估（HOMA-IR），糖基化血红蛋白（HbA1c）伴有血浆胰岛素，总血红蛋白和体重的减少。糖尿病大鼠糖代谢的关键酶，脂质过氧化标记，抗氧化酶，糖原含量和糖原合酶和糖原磷酸化酶的活性也发生了改变。

讨论：对糖尿病大鼠口服茶黄素可明显改善所有生化改变，使其接近正常水平。本研究的结果表明茶黄素通过其抗氧化活性表现出抗糖尿病作用。