Insulin secretory actions of polyphenols of Momordica charantia regulate glucose homeostasis in alloxan-induced type 2 diabetic rats

Abstract

Momordica charantia, commonly known as bitter gourd, is traditionally used as remedies for various diseases including diabetes. The main objective of this study is to investigate the in vitro and in vivo insulinotropic and anti-diabetic effects of an 80% ethanolic extract of Momordica charantia (EEMC) fruit, as well as the underlying molecular mechanism involved and preliminary phytochemical screening. The insulin secretion was measured using clonal pancreatic BRIN-BD11 β-cells and isolated mouse islets. The ability of EEMC to inhibit carbohydrate digestive enzymes and glucose absorption and, scavenge free radicals were assessed via starch digestion, glucose diffusion and DPPH assay methods. The effects of EEMC on a variety of metabolic parameters were evaluated in alloxan-induced type 2 diabetic rats, including lipid profile. Finally, a preliminary phytochemical screening was conducted to identify the active phytoconstituents. EEMC increased insulin release through the KATP-dependent/cAMP pathway, which depolarizes the β-cell membrane and elevates intracellular calcium. It also inhibited glucose absorption and free radicals, suggesting its potential to delay gastric emptying, attenuate oxidative stress, and reduce inflammatory cytokines. In vivo studies showed that EEMC improves oral glucose tolerance, food intake, fasting blood glucose, plasma insulin, lipids, and promotes intestinal motility. The active phytoconstituents in EEMC, such as flavonoids, alkaloids, tannins, saponins, steroids, and glycosides, are likely responsible for these effects. The antihyperglycemic properties of EEMC indicate that it might be a promising candidate for diabetes management. However, additional study into the application of Momordica charantia in type 2 diabetes is essential.