EVALUATION OF ANTIOXIDANT ACTIVITY OF CARICA PAPAYA LEAVES

Abstract

Oxidative stress is the underlying causative mechanisms for various diseases. It is an imbalance in the body between free radicals‟ generation and antioxidants. Oxygen-derived free radicals, which instigates damage to cellular constituents have been reported to play a decisive role in the pathogenesis of a broad spectrum of degenerative and chronic disorders such as diabetes mellitus and cancer. C. papaya, commonly called pawpaw is a flowering plant with succulent fruits and other components that are therapeutically and nutritionally beneficial. This study aims at evaluating the antioxidant activity of C. papaya leaf methanol extract in streptozotocin (STZ) induced diabetic rats. The bioactive components from C. papaya leaves was extracted with 70% methanol, to get the crude extract. Qualitative phytochemical screening of the leaf extract was done, and the total antioxidant capacity (TAC) and Hydrogen peroxide radical scavenging activity of the extract were determined in vitro according to the methods by Prieto et al. (1998) and Ruch et al. (1989) respectively. Thirty (30) male wistar albino rats were randomly allocated into five (5) groups comprising of six (6) rats each; groups 1 and 2 were the control, groups 3 and 4 were the diabetic rats given 100mg/kg and 200mg/kg body weight of plant extract respectively, while group 5 were diabetic rats given the standard drug metformin. Diabetes was induced by single intraperitoneal injection of STZ (55mg/kg body weight) in citrate buffer (4.5) after fasting the animals overnight. Plasma glucose concentration in the experimental rats was determined according to glucose oxidase methods using Randox assay kit. The activities of superoxide dismutase and catalase in the plasma and liver of experimental animals were determined according to the method of Misra and Fridovich (1972) and Singha (1972) respectively.