TOXICITY, ANTI ULCER, ANTIOXIDANT AND PHYTOCHEMICAL EVALUATIONS OF ETHANOLIC EXTRACT FORMULATIONS OF PSIDIUM GUAJAVA L. AND TERMINALIA CATAPPA L. LEAVES

ABSTRACT

Psidium guajava L. and Terminalia catappa L. are plants commonly grown for their edible fruits. Their leaf extracts have separately been reported to possess different biological activities, anti-ulcer activity inclusive. This study was designed to investigate the toxicity threshold, anti-ulcer and antioxidant activities, as well as phytochemical composition ofethanolic leaf extract formulations of P. guajava and T. catappa. The leaf extracts were formulated into three different ratios; 1:1, 1:2 and 2:1 of P. guajava and T. catappa respectively. It was observered that the LD₅₀ of 1:1 extract formulation is above 10,000 mg/kg b.wt. While a twenty-eight days sub acute toxicity study revealed a non significant difference (P>0.05) in rat body weights and organ-body weight ratio between the treated groups and control. General haematological indices and biochemical markers also did not reveal any significant difference (P>0.05) between the groups that is indicative of toxicity. Histological evaluations however revealed a deviation from normal hepatic, renal, heart and spleen tissues architecture in the extract formulation treated groups especially at the highest dose of 800 mg/kg b.wt. Anti-ulcer activity showed that 200 mg of 1:2 and 2:1 extract formulations significantly (P<0.05) inhibited ulcerations in the gastro-protective model. In the ulcer healing model, the 400 mg/kg b.wt. of 1:1 extract treatment recorded the lowest ulcer index. The potential mechanism of action is through antioxidative activity. Antioxidant study, demonstrated that the 200 mg/kg b.wt treated group possess highly significant (P<0.001) in vivo antioxidant activity in the superoxide dismutase and lipid peroxidation assays. The extract formulations also demonstrated 2, 2-Diphenyl-1-picrylhydrazyl and nitric oxide radical scavenging activities. The presence of flavonoids, phenols, tannins, saponins, alkaloids, steroids and triterpenes may be responsible for the antioxidant activities observed. It is evident that a combination of P. guajava and T. catappa leaf extracts is a good candidate for the development of a potent and relatively safe therapy in ulcer management.