Protein extract from fruit pulp of Siamese momordica charantia with insulin secretagogue and insulin-like activities

Abstract

The aim of this study was to investigate the effects of zinc-free protein extract from bitter gourd fruit pulp on plasma glucose concentration and insulin responses in normal and STZ-induced diabetic rats. Furthermore, we investigated the direct effect of the MC protein extract on insulin and glucagons secretions from the perfused rat pancreas as well as glucose uptake in C2C12 rat myocytes and 3T3-L1 rat adipocytes. The protein from Thai bitter gourd (Momordica charantia) fruit pulp was extracted and studied for its hypoglycemic effect. Subcutaneous administration of the protein extract (5 and 10 mg/kg) significantly and markedly decreased plasma glucose concentrations in both normal and streptozotocin-induced diabetic rats in a dose-dependent manner. The onset of the protein extract-induced antihyperglycemia/hypoglycemia was observed at 4 and 6 h in diabetic and normal rats, respectively. This protein extract also raised plasma insulin concentrations by 2 fold 4 h following subcutaneous administration. In perfused rat pancreas, the protein extract (10 [M]g/ml) increased insulin secretion, but not glucagons secretion, which was apparent within 5 min of administration and was persistent during 30 min of administration. Furthermore, the protein extract enhanced glucose uptake into C2C12 myocytes and 3T3-L1 adipocytes. Thus, the M. charantia protein has both insulin secretagogue and insulin-like activities that could help explain its hypoglycemic effect in vivo.