Syringaresinol-di-O-β-D-glucoside, a phenolic compound from Polygonatum sibiricum, exhibits an antidiabetic and antioxidative effect on a streptozotocin-induced mouse model of diabetes

Syringaresinol-di-O-β-D-glucoside (SOG) is a phenolic compound extracted from Polygonatum sibiricum. The present study aimed to investigate the antidiabetic effect of SOG on streptozocin (STZ)-induced diabetic mice and determine the potential underlying mechanisms. In the present study, fasting blood glucose and organ indexes of mice were analyzed. Body weight, water intake and food intake were also recorded. Furthermore, serum fasting insulin, pancreatic insulin and pancreatic interleukin-6 levels of mice were determined using ELISA kits to investigate the effect of SOG on the levels of insulin. Levels of total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL-C) and free fatty acid (FFA) in the serum of mice, and levels of TC, TG and total protein in the kidney, were also determined to investigate the effects of SOG on lipid and protein metabolism in mice. Furthermore, malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), aspartate transaminase (AST), alanine transaminase (ALT) and alkaline phosphatase (ALP) levels, as well as total antioxidant capacity (T-AOC), in the kidneys of mice were determined to investigate the effect of SOG on oxidative stress. Western blotting was also performed to determine the expression of proteins associated with oxidative stress. The results demonstrated that SOG (25, 50 and 75 mg/kg) induced a significant antidiabetic effect in mice. Treatment with SOG promoted insulin secretion and decreased TC, TG, LDL-C, VLDL-C, FFA, MDA, SOD, CAT, AST, ALT and ALP levels in the kidneys of mice, as well as kidney TC and TG levels, but increased the levels of kidney total protein and the T-AOC in kidneys. Furthermore, SOG treatment could significantly downregulate the expressions of nitrotyrosine and transforming growth factor-β1 in diabetic mice. Therefore, the present study indicated that SOG may exert an antidiabetic effect on STZ-induced diabetic mice and that the mechanism of SOG may be associated with its antioxidative activity.