Abstract
For centuries, medicinal plants have been a source of new compounds for drug discovery and researchers have developed interest towards the use of medicinal plants as sources for treating microbial infections and the damaging effects of free radicals, which are the leading causes of morbidity worldwide. Terminalia avicennoides is a plant of medicinal importance. This study aimed at evaluating the antimicrobial and antioxidant effects of methanol leaf extract of T. avicennioides in albino rats. The plant’s leaves were extracted with methanol to obtain the active constituents. Phytochemical screenings were carried out qualitatively and quantitatively. The methanol extract of the plant was partitioned with butanol, n-hexane, ethyl acetate and aqueous solvents and each fraction was tested against E. coli, Klebsiella pneumoniae, Streptococcus pneumonia and Candida albicans in comparison with a standard drug for each microbial strain, previously subjected to a drug susceptibility test. The aqueous fraction showed the most potent activity. The LD50 was determined to be greater than 5000mg/kg. The antioxidant activity was investigated against CCL4 induced hepatotoxicity. Thirty rats were divided into six groups of five rats each. Group I served as normal control and received 5ml/kg b.wt of distilled water for 14 days. Group II served as the negative control and received CCl4 0.2% 10ml/kg only. Group III served as the positive control and received standard drug- silymarin (100mg/kg b.wt). Groups IV, V and VI were administered orally with the plant extract at 100, 200 and 400mg/kg for 14 days, after which blood and liver samples were collected for biochemical and histological analyses. Antioxidant markers such as Glutathione, Superoxide dismutase, Catalase, Vitamin A and C levels were reduced in group II compared to groups 1, III, IV, V and VI. Malondialdehyde levels were high in group II when compared with other groups. The hepatoprotective activity of the plant extract groups were comparable with the standard drug- silymarin. There was no significant change in Vitamin E levels. Data from this research shows that T. avicennioides posesses antimicrobial and hepatoprotective activities. However, the presence of phytochemicals may be responsible for the antimicrobial and antioxidant effects observed in this study.

Key words: Terminalia avicennioides, carbon tetrachloride (CCl4), antioxidant, antimicrobial, silymarin, phytochemicals.