Abstract

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Hyptis suaveolens is an important plant used traditionally as an ethnomedicine and widely distributed in Nigeria as well as African and Asian countries. In this study, antibacterial activity of ethanolic leaves extract of H. suaveolens was conducted. The plant metabolite was extracted using standard protocols and the antibacterial activity of the extracts was evaluated using the standard in-vitro methods against four (4) clinical isolates; Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Streptococcus pyogenes. The result of the study revealed that the extraction process gave a yield of 6.2g extract (6.2%) of the original sample used. The plant extract exhibited a dose-dependent antibacterial activity against the test isolates with higher zone of inhibition of 18.67±0.33mm against S. aureus, followed by E. coli with 17.33±0.12mm both at 100mg/mL while lowest activity was recorded against S. pyogenes (6.1±0.66mm) at 12.5mg/mL. S. aureus showed a significant antibacterial activity, even at 12.5 mg/mL with the activity more pronounced at highest concentration of 100mg/mL. There was a dose-dependent increase in antibacterial activity across all test isolates. It was also the most susceptible of the isolates at all concentration while P. aeruginosa was the most resistant at all concentrations. E. coli and S. aureus had the lowest MIC of 25mg/mL and S. pyogenes had and 50mg/mL as its MIC, while P. aeruginosa on the other hand showed growth at all concentrations tested. Results of minimum bactericidal concentration showed that both the concentrations of 50 to 12.5mg/mL are unable to kill the gram negative isolates (E. coli and P. aeruginosa) while for the gram positive isolates (S. aureus and S. pyogenes) the concentration of 50mg/mL was found to totally kill the test isolates thus representing their Minimum Bactericidal Concentration (MBC). The study confirms that the leaves of H. suaveolens exhibited some antimicrobial activities owing to its significant zone of inhibition, lesser MIC and MBC as well as its broad spectrum of activity. Further phytochemical and pharmacological investigations are recommended.

Keywords: Antibacterial, Extract, Hyptis suaveolens, ethnomedicine, in - vitro