In vitro antimicrobial activity of crude ethanol extracts and fractions of Terminalia catappa and Vitex doniana

Abstract

Background: The spread of resistant to some antimicrobial agents necessitates the need to search for novel and effective . In this study, the antimicrobial activity of Terminalia catappa Linn. (Combretaceae) and Vitex doniana Sweet. (Verbenaceae), two Nigerian medicinal plants used in folk medicines for the management of various ailments related to microbial infections were evaluated. Objectives'. To evaluate the antimicrobial activity of the crude ethanol extracts and fractions of the leaves and stem bark of T. catappa and V doniana Methodology: Fou. crude ethanol extracts and 16 (//-hexane, ethyl acetate, //-butanol and aqueous) fractions of leaves and stem bark of T. catappa and V. doniana were evaluated for in vitro antimicrobial activity against fifteen (15) strains of bacteria and fungi. The antimicrobial activity was determined in a 96-well plate using a resazurin based broth microdilution method. Two standard antimicrobial drugs ampicillin and nystatin were included as positive control. Results: The butanol fraction of stem bark of T. catappa and ethanol crude extract of leaf of V. doniana displayed the highest antibacterial activity with similar minimum inhibitory concentration (MIC) value of 93.75 jig/mL against S. aureus and B. subtilis. Furthermore, the ethyl acetate fraction of stem bark of T. catappa showed the highest antifungal activity with MIC of 187.5 ftg/mL against A. sydowi. Ampicillin had MIC of 15.6 and 31.3 j.ig/ mL against S. aureus and B. subtili, respectively while nystatin produced MIC of 3.9 fig/mL against A. sydowi. Conclusion: Terminalia catappa and Vitex doniana may serve as useful source s of plant derived antimicrobial agents.