Effect of fermented soybean condiment supplemented diet on α-amylase and α-glucosidase activities in Streptozotocin-induced diabetic rats

• Fermented soybean based diets improved glycaemic status in STZ-induced diabetic rats.
• Inhibit α-amylase and intestinal α-glucosidase activities in the diabetic rats.
• Improved in vivo antioxidant status was also observed in the diabetic rats.
• HPLC characterization revealed presence of some phenolic constituents in the condiment.

Inverse correlation exists between soybean consumption and incidences of some degenerative diseases such as diabetes. Thus, this work sought to investigate the antidiabetic effects of fermented soybean diet in streptozotocin (STZ)-induced diabetic rats. The rats were made diabetic by intraperitoneal administration of STZ (35 mg/kg b.w.) and fed diets containing 10% fermented soybean for 14 days. The effect of the diet on blood glucose, pancreatic glutathione peroxidase (GPx) activity, reduced glutathione (GSH) and thiobarbituric acid reactive species (TBARS) contents, α-amylase and intestinal α-glucosidase activities were investigated. Marked increase in the blood glucose, TBARS, α-amylase and intestinal α-glucosidase with corresponding decrease in pancreatic GPx and GSH contents were observed in diabetic rats. These trends were however, reversed in diabetic rats fed diet supplemented with fermented soybean for 14 days. Also, extract of the fermented soybean exhibited α-amylase and α-glucosidase inhibitory activity in vitro. The proximate composition of the fermented soybean revealed high crude protein content. Furthermore, the HPLC analysis of the soybean product indicated the presence of some phenolic phytochemicals. Thus, the antidiabetes property of the fermented soybean condiment may be attributed to the influence of its constituent phytochemicals on starch digestion and, α-amylase and α-glucosidase activities.