Phytochemical screening and in vitro evaluation of the antibacterial properties of Terminalia macroptera stem bark extracts against selected pathogenic bacteria

摘要

Terminalia macroptera alstone belonging to the Combretaceae family have been investigated for evaluation of their phytocchemical composition and antibacterial properties. Aqueous and ethanolic70% extract of plant were tested against three clinical strains of Escherichia coli (ESBL) and three clinical strains of Klebsiella pneumonia (ESBL), by well plate and dilution methods. Selected antibacterial agents (ceftazidim and ceftriaxon) were used as positive reference standards in the tests. The screening revealed the presence of metabolites such as flavonoids, phenolic compounds, tanins, saponins, sterols, terpens and cardiac glycosids. The aqueous extract has presented a bacteriostic power against almost tested strains through a ratio MBC/MIC=4. However, ethanolic70% extract showed strong antibacterial activity against E. coli with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) ranged from 6.25 to 25 mg/ml and 12.50 to 50 mg/ml, respectively. It also showed on K. pneumonia strains MIC varying between 6.25 and 50 mg/ml and MBC 12.50 to 50 mg/ml. So ethanolic70% extract was found to be potential bactericidal against all strains tested.