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Thai J Pharmacol Vol. 31, No.1, 2009 Original article
P04
Antidiabetic Effect of Grape Seed Extract (Vitis vinifera)
in High Fructose-Fed Rats

Wannaporn Suwannaphet1, Sirichai Adisakwattana2, Sirintorn Yibchok-anun3
Interdepartment of Pharmacology, Graduate School, 2The Medical Food Research and Development Center, Department of Transfusion Medicine, Faculty of Allied Health Sciences, 3Department of Pharmacology, Faculty of Veterinary Sciences, Chulalongkorn University, Thailand E-mail: Suwannaphet_wanna@hotmail.com Abstract
Type 2 diabetes is a chronic disease characterized by insulin resistance and/or an inadequate compensatory insulin secretory response. Grape seed extract (GSE) has been reported to possess antidiabetic activity. However, there was no the literature reported to the effect of grape seed extract on plasma glucose in high fructose-fed rats. The present study was performed to investigate the antihyperglycemic effects of grape seed extract in high fructose-fed rats. Phenolic compounds and flavonoids content in grape seed extract was determined by using Folin-Ciocalteu’s reagent and AlCl3 assay. Six experimental groups were compared: a control group receiving the control diet, a high-fructose-fed group where 60% of the diet carbohydrate was fructose, a high-fructose-fed group supplemented with 0.5, 1 and 2% GSE, respectively. The sixth group received the high fructose diet and rosiglitazone (4 mg/kg). After 8 weeks of experiment, fasting plasma glucose concentrations were measured and oral glucose tolerance test were performed in each group. Total phenolic compounds and flavonoids content were 2.16±0.01 and 7.39±0.45 mg/g extract respectively. The diabetic rats supplemented with 1% GSE significantly decreased fasting plasma glucose level (p<0.05) after 8 weeks of administration. Moreover, the diabetic rats supplemented with GSE at 1 and 2% improved glucose intolerance when compared to the diabetic control group (p<0.05). In conclusion, the present results indicated that grape seed extract reduced hyperglycemia in high fructose-induced diabetic rats. Thus, grape seed extract may be useful in the prevention for type 2 diabetes. Keywords: Grape seed, diabetic rats, high-fructose diet
Introduction
Diabetes mellitus is a group of metabolic diseases characterized by hyperglycemia, dyslipidemia, and protein metabolism that results from defects in both regulations of insulin secretion and/or insulin action. Diabetes mellitus is associated with a reduced quality of life and increased risk factors for mortality and morbidity. The prevalence of diabetic patients in worldwide has dramatically increased every year because of lifestyle and eating behavior changed by consumption of a high-carbohydrate diet. Fructose is consumed in significant amounts in both Asian and Western diets. The long term consumption of fructose-enriched diets has been associated with increasing risk factor of obesity and metabolic disorders especially diabetes mellitus. Interestingly, a large amount of fructose or sucrose (>60% of total calories) consumed in human produce a decline in insulin sensitivity in the liver and peripheral tissues (1), leading to development of type 2 diabetes mellitus. Grape seeds, a rich source of phenolic compounds (2-5), possess a broad spectrum of antioxidative properties that protects various cells from free radicals and oxidative stress. Recently, they have reported to antihyperglycemic activity of GSE in streptozotocin (STZ)-

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