Insulin-secretagogue activity of p-methoxycinnamic acid in rats, perfused rat pancreas and pancreatic β-cell line

This study investigated the effect of p-methoxycinnamic acid (p-MCA) on plasma glucose and insulin concentrations in normal and streptozotocin-induced diabetic rats. In both fasting and glucose-loading conditions, an oral administration of p-MCA (40-100 mg/kg) significantly decreased plasma glucose and also increased plasma insulin concentrations in both normal and diabetic rats. The onset of the p-MCA-induced antihyperglycaemia/hypoglycaemia was observed at 1 hr after administration. In perfused rat pancreas, p-MCA (10-100 mu M) stimulated insulin secretion about 1.4- and 3.1-fold of basal-control group. In addition, p-MCA (10 mu M) enhanced glucose-induced insulin secretion. Moreover, p-MCA stimulated insulin secretion and increased intracellular Ca2+ concentration ([Ca2+](i)) in insulinoma-1 cells. Taken together, our findings suggested that p-MCA exerted antihyperglycaemic/hypoglycaemic effect by stimulating insulin secretion from pancreas and could be developed into a new potential for therapeutic agent used in type 2 diabetic patients.