RESUMO
Aim: To assess the antibacterial activities and phytochemical potential of Cochlospermum planchonii (Apocynaceae), Terminalia avicennoides (Papilionaceae) and Pericopsis laxiflora (Papilionaceae) used traditionally against typhoid fever and bacterial gastroenteritis. Study Design: In this study, hot water, hexane and methanol extracts obtained from the test plants were screened for phytochemicals according to standard procedures. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays were employed to determine the plant extracts susceptibilities to the test bacteria. Place and Duration of the Study: Extraction was performed at the Chemistry laboratory, Benue State University while phytochemical screening and in vitro analyses were carried out at the Bacterial Research Division, National Veterinary and Research Institute Vom, Nigeria. All studies lasted for 12 months. Methodology: Preparation of plant extracts, phytochemical analyses of the plant parts, agar well diffusion assay, determination of Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) was used to evaluate antibacterial activities. The Zones of Inhibition of various concentrations of extracts against test bacteria were also measured. Results were compared with standard antibiotic discs. Results: Phytochemical studies reveal that while saponins were present in all the test plants anthraquinone was absent. Also, tannins, alkaloids, essential and volatile oils, flavonoids, phlobatannins, and steroids were identified in one or more of the plants. Findings from antibacterial activity reveal that Gram-positive bacteria were more sensitive to the extracts, by comparison to the Gram-negative bacteria. The hexane extracts of both C. planchonii and P. laxiflora extracts inhibited Bacillus cereus at 0.165 μg ml-1, while T. avicennoides hexane extract and decoction showed the least MIC of 0.33 μg ml-1 against Stahylococcus aureus. Conclusion: The positive correlations of the results obtained here confirm the acclaimed ethnomedical uses, while also providing a potential source for discovering new pharmaceutical compounds with antibacterial activity.