Antihyperglycemic activity of quince (Cydonia oblonga Mill.) fruit extract and its fractions in the rat model of diabetes

Introduction: Diabetes mellitus is a metabolic disease that has affected approximately 10% of population worldwide. Cydonia oblonga Mill. (C. oblonga), commonly called quince, contains diverse phytochemical constituents with a broad range of pharmacological activities. The current study is aimed to investigate the antihyperglycemic effect of aqueous extract of Cydonia oblonga Mill. fruit (ACO) in streptozotocin-induced diabetic rats and to identify the active fraction. Methods and Results: Diabetes was induced in rats by a single intraperitoneal (i.p.) injection of 60 mg/kg streptozotocin. The antihyperglycemic activity of different concentrations of ACO (80, 160 and 240 mg/kg body weight daily for a period of 28 days) was evaluated in the diabetic rats by measuring their fasting blood glucose (FBG). Furthermore, the antihyperglycemic effects of two major fractions of ACO were evaluated for the identification of active fraction. Finally, the chemical composition of the active fraction, methanolic fraction (MF), was examined by gas chromatography-mass spectrometry (GC-MS) assay. The oral administration of ACO on diabetic rats resulted in a significant collapse in FBG in a dose-dependent manner. In addition, the MF was the active fraction and exhibited antihyperglycemic activity in diabetic rats during the experiment. The main component of MF was identified as 5-hydroxymethylfurfural or 5-HMF (a well-known natural compound) that may be responsible, at least partly, for the antidiabetic and antihyperglycemic effects of quince. Conclusion: Our results have demonstrated for the first time that quince possesses antihyperglycemic effect in diabetic rats and the MF of the aqueous extract is active fraction. Keywords: Antidiabetes; C. oblonga; 2,5-dimethyl-4-hydroxy-3(2H)-furanone; GC-MS; 5-Hydroxymethylfurfural; Polyphenol