Antidiabetic effects of onion peel extracts in insulin‐resistance rat induced with streptozotocin and high fat diet

Abstract

This study was performed to examine the antihyperglycemic effect of ethanolic onion peel extract, which contains high concentration of quercetin in streptozotocin‐induced diabetic rats. In the previous study, we confirmed that onion peel extract ameliorated IAUC for oral glucose tolereance test. In this study, we further analyzed the insulin sensitizing effect of onion peel supplementation. The glycogen concentration in the liver was significantly increased in the both of pure quercetin and 1.0% ethanolic onion peel extract groups (p<0.05). Insulin concentration in plasma and HOMA‐IR were not changed significantly, the plasma C‐peptide and free fatty acid (FFA) concentrations, however, were reduced by ethanolic onion peel extract in dose‐dependent manner. In addition, we revealed that the onion peel extract improved insulin resistance through antioxidant and anti‐inflammatory capacities of quercetin and other flavonoids in onion peel extracts.