Antiperoxidative, antithyroidal, antihyperglycemic and cardioprotective role of Citrus sinensis peel extract in male mice

An extract of Citrus sinensis (CS) peel was evaluated for its efficacy in ameliorating L-thyroxine (L-T-4) induced tissue lipid peroxidation (LPO), hyperthyroidism and hyperglycemia in mice. In a preliminary investigation, of the three different doses of CS (12.5 mg/kg, 25 mg/kg and 50.0 mg/kg) peel extract, 25 mg/kg was found to be the most effective and antiperoxidative, while 50 mg/kg was proved to be hepatotoxic. Therefore in the pilot experiment the effects of 25 mg/kg/day of CS for 10 days were studied in L-T-4 induced hyperthyroid animals. L-T4 (500 mu g/kg/day for 10 days) increased the levels of thyroxine (T-4) and triiodothyronine (T-3) with a concomitant increase in serum glucose concentration, alpha-amylase activity, heart/body weight ratio (HW/BW), kidney/body weight ratio (KW/BW) and cardiac as well as hepatic LPO. However, it decreased the concentration of different serum lipids such as total cholesterol (TC), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and very low-density lipoprotein cholesterol (VLDL-C). Administration of CS extract (25 mg/kg/day) in hyperthyroid animals reversed most of these observations revealing the ameliorating potential of CS extract against various adverse effects of hyperthyroidism. It appears that the test extract primarily acts through its antioxidative/free radical-scavenging, antithyroidal and HDL-C stimulating properties. Copyright (C) 2008 John Wiley & Sons, Ltd.