Studying some of the biological effects of some commercially available dietary supplements containing grape seed extract in type2 diabetic patients

Abstract

This study aims to determine the total content of phenolic compounds and the in vitro antioxidant activity of a preparation containing (500 mg) of Vitis Vinifera red grape seed extract (GSE) marketed by a local pharmaceutical company, in addition to evaluating the effect of its administration combined with metformin as an oral hypoglycemic agent on serum levels of some vital parameters such as fasting blood glucose, C-reactive protein, total cholesterol, triglycerides, LDL-cholesterol, and HDL-cholesterol in newly diagnosed patients with type 2 diabetes mellitus (T2DM). The total content of phenolic compounds of the studied product, measured using the Folin Ciocalto method and expressed as (gallic acid equivalents GAE), was (48.5 ± 2.07 mg GAE/500 mg GSE), while the antioxidant activity of the studied product measured by the Reducing Power method, expressed by the molar concentration of ferrous sulfate was (245.86 ± 12.02 µmol Fe⁺²/500 mg GSE). The 53 patients attending the endocrinology department at Tishreen University Hospital in Lattakia were divided into two groups, the participant group (n = 25) who were treated with metformin as a hypoglycemic in combination with a grape seed extract preparation (500 mg) once daily and the control group (n = 28) who were treated with metformin only. Taking a grape seed extract preparation once daily for 12 weeks resulted in a statistically significant decrease in mean levels of fasting blood glucose (99.48 ± 13.62 mg/dl), C-reactive protein (2.46 ± 1.25 mg/dl), total cholesterol (160.92 ± 25.95 mg/dl), and LDL-cholesterol (98.52 ± 21.17 mg/dl) (P=0.000, P=0.001, P=0.001, P=0.03, respectively), compared with their levels at the beginning of the study in the participation group (120.36 ± 17.32 mg/dl, 5.39 ± 3.96 mg/dl, 191.62 ± 31.45 mg/dl, 116.32 ± 31.45 mg/dl respectively), and compared with their levels at the end of the study in the control group  (P=0.001, P=0.001, P=0.000, P=0.016, respectively) (111.70 ± 9.80 mg/dl, 3.78 ± 1.42 mg/dl, 185.41 ± 17.70 mg/dl, 111.50 ± 15.08 mg/dl respectively). The mean value of triglyceride levels decreased, while and the mean value of high-density lipoprotein cholesterol HDL levels increased without statistical significance at the end of the study between and within two groups.