Antidiabetic Potency, Antioxidant Effects, and Mode of Actions of Citrus reticulata Fruit Peel Hydroethanolic Extract, Hesperidin, and Quercetin in Nicotinamide/Streptozotocin-Induced Wistar Diabetic Rats.

This study is aimed at assessing the antihyperglycemic, antihyperlipidemic, and antioxidant effects of Citrus reticulata (C. reticulata) fruit peel hydroethanolic extract and two flavonoids, hesperidin and quercetin, in nicotinamide (NA)/streptozotocin- (STZ-) induced type 2 diabetic rats. In addition, GC-MS and HPLC-MS analyses of the extract were performed and the results indicated the presence of multiple flavonoids including hesperidin, quercetin, naringin, and polymethoxylated flavones (nobiletin and tangeretin). To achieve the aim of the study, diabetic rats with NA/STZ-induced T2DM were orally treated with C. reticulata fruit peel hydroethanolic extract, hesperidin, and quercetin at a dose of 100 mg/kg b.w./day for four weeks. The treatments with C. reticulata fruit peel extract, hesperidin, and quercetin significantly ameliorated the impaired oral glucose tolerance; the elevated serum fructosamine level; the diminished serum insulin and C-peptide levels; the altered HOMA-IR, HOMA-IS, and HOMA-ß cell function; the decreased liver glycogen content; the increased liver glucose-6-phosphatase and glycogen phosphorylase activities; the deleteriously affected serum lipid profile; the elevated serum AST and ALT activities; and the raised serum creatinine and urea levels in the diabetic rats. The treatments also produced remarkable improvement in the antioxidant defense system manifested by a decrease in the elevated liver lipid peroxidation and an increase in the lowered glutathione content and GPx, GST, and SOD activities. Furthermore, the three treatments enhanced the mRNA expression of GLUT-4 and the insulin receptor ß-subunit, but only quercetin produced a significant increase in the expression of adiponectin in adipose tissue of diabetic rats. In conclusion, C. reticulata fruit peel hydroethanolic extract, hesperidin, and quercetin have potent antidiabetic effects which may be mediated through their insulinotropic effects and insulin-sensitizing actions. In addition, the alleviation of the antioxidant defense system by the extract, hesperidin, and naringin may have an important action to enhance the antidiabetic actions and to improve liver and kidney functions in NA/STZ-induced diabetic rats.

Navel orange peel hydroethanolic extract, naringin and naringenin have anti-diabetic potentials in type 2 diabetic rats.

The therapy of Type 2 Diabetes Mellitus (T2DM) stays a challenging issue. During the last decade, there has been an interest in the expansion of anti-diabetic drugs especially those of natural sources. Thus, the aim of this study was to assess the anti-hyperglycemic and the anti-hyperlipidemic effects as well as the anti-oxidant activities of navel orange hydroethanolic extract and its constituting flavonoids naringin and naringenin on nicotineamide (NA)/streptozotocin (STZ)-induced type 2 diabetic rats. To induce T2DM, 16h-fasted rats were intraperitoneally injected with STZ at dose of 50mg/kg body weight (b. w.), 15min after the intraperitoneal administration of NA (120mg/kg b. w.). The NA/STZ-induced type 2 diabetic rats were orally treated with navel orange peel hydroethanolic extract, naringin and narengenin at dose level of 100mg/kg b. w./day for 4 weeks. The treatments with navel orange peel hydroethanolic extract, naringin and narengenin potentially alleviated the lowered serum insulin and C-peptide levels, the depleted liver glycogen content, the elevated liver glucose-6-phosphatase and glycogen phosphorylase activities, the deteriorated serum lipid profile, and the suppressed liver antioxidant defense system of NA/STZ-induced type 2 diabetic rats. The treatments also enhanced the mRNA expression of insulin receptor ß-subunit, GLUT4 and adiponectin in adipose tissue of STZ/NA-induced type 2 diabetic rats. In conclusion, the navel orange peel hydroethanolic extract, naringin and naringenin have potent anti-diabetic effects in NA/STZ-induced type 2 diabetic rats via their insulinotropic effects and insulin improving action which in turn may be mediated through enhancing insulin receptor, GLUT4 and adiponectin expression in adipose tissue.