Fermented rice germ extract ameliorates abnormal glucose metabolism via antioxidant activity in type 2 diabetes mellitus mice

Rice germ is an abundant source of ferulic acid, which is known for its anti-oxidant activity. This study aimed to evaluate the regulatory effects of fermented rice germ extracts on hepatic glucose metabolism in C57BL/KsJ-db/db mice. Rice germ was fermented with Lactobacillus plantarum and extracted with 30% ethanol (RG_30E) or 50% ethanol (RG_50E). Mice were fed modified AIN-93 diets containing fermented rice germ extracts and ferulic acid for 8 weeks. RG_50E significantly reduced food intake as well as liver weight and RG_30E and RG_50E improved glucose homeostasis, as indicated by fasting blood glucose levels and glucose tolerance. Hepatic triglyceride and total cholesterol levels were significantly decreased in db/db mice fed RG_30E and RG_50E. The antioxidant capacity of RG_30E and RG_50E was confirmed by a decrease in malondialdehyde levels and an increase in hepatic superoxide dismutase activity. The expression of genes related to glycolysis and gluconeogenesis was significantly regulated by RG_30E and RG_50E. These results suggest that fermented rice germ extracts have the potential to regulate hypoglycemia and hepatic glucose metabolism in type 2 diabetes db/db mice.