Antidiabetic and Antioxidant Activities of Zizyphus lotus L Aqueous Extracts in Wistar Rats

Abstract

Objectives: Zizyphus lotus L. is a medicinal plant, used in traditional medicine for its multiple therapeutic properties. The aim of the present study was to determine the antidiabetic and antioxidant effects of aqueous extracts of different parts of Zizyphus lotus in diabetic Wistar rats. Research methods and procedures: The male Wistar rats were rendered diabetic by intraperitoneal (i.p.) injection of streptozotocin (40 mg/kg body weight). Aqueous extracts from different parts, i.e, root, leaf, and seed of Zizyphus lotus L. were prepared and administrated orally to the animals at the dose of 300 mg/kg for 21 days. Blood glucose level was measured, and antioxidant status was assessed by determining oxygen radical absorbance capacity (ORAC) and the activities of enzymes like catalase, glutathione reductase and peroxidase in pancreas, liver, and erythrocytes. Vitamin C levels were determined by precipitating with 10% trichloroacetic acid. Vitamins A and E concentrations were measured by HPLC. Results: The leaf and root, but not seed, extracts exerted the glucose lowering effect on 21st day of postadministration. The leaf and root extracts corrected antioxidant status of diabetic animals in pancreas, liver and erythrocytes. The concentrations of different vitamins (vitamin A, C and E) in diabetic rats were also modulated by leaf and root, but not seed, extracts. Conclusion(s): Our study shows that oral administration of Zizyphus lotus L. extracts from roots and leaves exerted antidiabetic and antioxidant effects in diabetic rats. Z. lotus L. seems to be a good candidate to lower, in addition to conventional antidiabetic drugs, the hyperglycaemia in diabetic subjects. Keywords: Zizyphus lotus L; Streptozotocin; Diabetes; Antioxidants Introduction Zizyphus lotus L., also known as Jujube, is a medicinal plant largely found in the Mediterranean region including Algeria [1]. The fruit of this plant is consumed by local population for the treatment of several pathologies such as digestive disorders, obesity, urinary troubles and skin infections [2,3]. In traditional medicine, jujube is used for treatment of liver diseases [4], insomnia and anxiety [5]. Z. jujuba extracts showed protection against hydroquinone-induced cytogenesis [6]. In Algeria, Zizyphus lotus L. is used for its antidiabetic, sedative and hypoglycemic properties [7]. The medicinal properties of this plant depend on the part of the plant and the extract used. For instance, fruit has been used for its emollient effects and leaves are known for the beneficial effects in the boils. Interestingly, the root barks are known for their antidiabetic property [8]. The butanol extracts of the leaves of Zizyphus spina-christi, another plant of the same family, improved the oral glucose tolerance and potentiated the glucose-induced insulin release in type II diabetic rats [9]. Anti-inflammatory, analgesic and anti-ulcerogenic activities of this plant have been demonstrated in rodents [10,11]. We have recently shown that fruit, leaves and seeds are rich in different vitamins and exhibit in vitro antioxidant properties [12]. We have also shown that these extracts exert immunomodulatory properties on human T-cell activation and IL-2 mRNA expression [13]. Diabetes is a serious metabolic disorder affecting the metabolism of carbohydrate, protein and fat. A number of studies have shown that diabetes mellitus is associated with oxidative stress, leading to an increased production of reactive oxygen species. Recently, the protein hydrolysates isolated from