Abstract

This work focused on the effect of Coscinium fenestratum ethanolic extract on plasma glucose concentrations in normal and streptozotocin (STZ)-induced diabetic rats, the stimulatory effect on insulin secretion from perfused rat pancreas and the inhibitory effects on rat intestinal α-glucosidase enzymes, maltase and sucrase. In oral glucose, maltose and sucrose loading tests, the extract (250 - 1,000 mg/kg) significantly decreased plasma glucose concentrations in a dose-dependent manner. The extract (1,000 mg/kg) was most effective in decreasing plasma glucose concentrations and the response was closed to those of glibenclamide (5 mg/kg) and acarbose (3 mg/kg). In perfused rat pancreas, the extract (10 µg/ml) stimulated insulin secretion in a biphasic pattern. However, the berberine at the same dose as the extract slightly increased insulin secretion by 1.33-fold over the basal control group. In addition, the extract inhibited the activities of both maltase and sucrase with the IC₅₀ of 3.89 and 11.22 mg/ml, respectively. Our findings suggest that the C. fenestratum ethanolic extract exerted anti-hyperglycemic activity by stimulating insulin secretion and a-glucosidase inhibition.

Key words: Coscinium fenestratum, streptozotocin, a-glucosidase, insulin secretion, perfused rat pancreas.