ABSTRACT

C. papaya, L. (Caricaceae) is an herbaceous perennial tree crop commonly cultivated for its ripe edible fruit. Several parts of the plant are used locally for the treatment of constipation, dengue fever, malaria, convulsion and indigestion. This study investigated the antioxidant, anticonvulsant, toxicological and preliminary phytochemical properties of the aqueous leaf extract of C. papaya. Matured fresh leaves of C. papaya were collected, dried and pulverized before extraction by aqueous decoction. The extract was then concentrated to dryness and kept in sealed bottle for further use. In vitro studies was based on free radical scavenging activities of the extract in Ferric reducing anti-oxidant power(FRAP),2,2-Azinobis,3-Ethylbenzothiazoline-6-Sulphonic Acid (ABTS), Hydroxyl radical scavenging assay(OH^-)and 1,1-Diphenyl-2-Picrylhydrazyl (DPPH) assays. Maximal electroshock and pentylenetetrazole models of convulsion was performed. Acute toxicity test was evaluated in wistar mice using lorke’s method, while sub-acute toxicity was determined by assessment of hematological, biochemical and histopathological indices in wistar rats following oral administration of 200 mg/kg, 400 mg/kg and 800 mg/kg of the extract for 28 consecutive days. Qualitative phytochemical screening of the extract were performed according to laboratory proceedures.The aqueous leaf extract C. papaya demonstrated potent free radical scavenging activities in FRAP, DPPH, ABTS and OH^-. However, no anticonvulsant activity was recorded in both models used in the present study. Acute toxicity studies was estimated to be greater than 5000 mg/kg. The results from the 28 days oral daily repeated administration showed no significant change in the organ/body weight ratio of the rats, hematological indices were normal within acceptable limits in both test and control groups. There were no significant changes in the liver function and kidney function test analysis except for chloride and creatinine (p<0.05) in rats that received 800 mg/kg. However, photomicrographs revealed liver karyosis, mild inflammation of the lungs and tubular necrosis of the kidney. Tannins, flavonoids, steroids and saponins were the major secondary metabolites detected. They may be responsible for some of the activities present in this study.The study has shown that the extract possesses antioxidant and some toxicological effects, however, there was no evidence of any anticonvulsant activity.