Quercetin improves oxidative stress-induced pancreatic beta cell alterations via mTOR-signaling

Citrus flavonoids particularly quercetin which is abundant in grapefruit, onion, green tea, berries etc. are known to have a protective effect on oxidative stress. Pancreatic β cells which synthesize and secrete insulin are prone to oxidative stress induced damage because of low cellular antioxidant enzymes. To delineate the effects of quercetin on pancreatic β cells we evaluated the protective effect of quercetin on TC6 insulinoma cells subjected to oxidative stress induced by tert-butyl-hydrogen-peroxide (TBHP). Quercetin was found to reduce TBHP induced apoptosis and trigger insulin secretion in response to glucose, in a dose-dependent manner. Quercetin treatment increased mitochondrial biogenesis, caused hypertrophy in pancreatic β cells and activated mTOR signaling with a transient change in mitochondrial membrane potential and AMP/ATP. Activation of mTOR signaling resulted in enhanced insulin secretion in TC6 cells.