Effects of the methanolic extracts of Zizyphus spina christi, Olea europaea and Morus alba leaves in Streptozotocin- induced diabetic rats.

Abstract

Background:The present study aims to investigate the hypoglycemic, hypolipidimic and antioxidant effect of the methanolic crude extracts of Zizyphus spina christi, Morus alba and Olea europaea leaves, individually or in combination against diabetes induced rats by Streptozotocin (STZ). Results:Hyperglycemia and hyperlipidaemia except in high density lipoproteins (HDL) were observed in serum after 5 weeks of STZ administration. This was associated with a depression in hepatic glutathione (GSH) concentration as well as hepatic catalase (CAT), glutathione-s- transferase (GST) and superoxide dismutase (SOD) activates. In addition hepatic thiobarbituric acid-reactive substance (TBARS) and protein carbonyl (PC) were significantly elevated, indicating increased lipid and protein oxidation and oxidative stress. Depression in blood hemoglobin (Hb) content, serum insulin levels, total antioxidant capacity (TAOC) and nitric oxide (NO) levels as well as body weight gain were also observed in diabetic rats. Administration of 100mg/kg alcoholic extracts of Zizyphus spina christi, Morus alba and Olea europaea leaves 3 days before and after STZ injection daily for 5 weeks significantly ameliorated the oxidative stress evidenced by lowering TBARS & PC as well as increasing hepatic GSH concentration and CAT, GST and SOD activates as compared with STZ treated rats. These effects were paralleled with marked protection against STZ induced hyperglycemia and disturbance of lipid profile. They also caused a great improvement in insulin levels, TAOC, NO, Hb content and body weight gain. Conclussion:Thus, these results showed that the administration of the crude extracts of either Zizyphus spina christi, Morus alba or Olea europaea leaves individually or in combination might improve the clinical manifestation of diabetes and decrease the oxidative stress, this study supports the beneficial effects of these extracts especially Zizyphus spina christi, which showed marked amelioration and this may be attributed to the presence of saponin glycosides which have an inhibitory effect of serum glucose level in addition to enhance the cellular antioxidant defense. This activity contributes to the protection against oxidative damage in STZ induced diabetes.