Studies on the antibacterial activities of Ocimum basilicum and Psidium guajava

Abstract

The antibacterial activities of crude extracts of two local plants used in Nigeria for traditional medicine were tested against Escheriachia coli, Pseudomonas aeruginosa, Salmonella typhi, and Staphylococcus aureus. Extraction of active ingredients from the plants was done using water. Determination of the antibacterial activities was done using the Zone of Inhibition tests, Minimum Inhibitory Concentration (MIC) and Determination of the Fractional Inhibitory Concentration (FIC) Index. The two plants extracts exhibited anti-microbial activities against the four test microorganisms. The minimum inhibitory concentration of the plants were 62.5 mg/ml and 62.5 mg/ml, 31.25 mg/ml for E. coli, P. aeruginosa, S. typhi and S. aureus respectively, while MIC values for P. guajava were 125 mg/ml, 62.5 mg/ml, 125 mg/ml and 250 mg/ml for E. coli, P. aeruginosa, S. typhi and S. aureus respectively. The Minimum Inhibitory Concentration (MIC) of combined aqueous extracts were also determined the values were 125 mg/ml, 31.25 mg/ml, 125 mg/ml and 62.5 mg/ml for E. coli, P. aeruginosa, S. typhi and S. aureus respectively. FIC values of the combined plant extracts were 3, 1.5, 5.0 and 1.25 for E. coli, P. aeruginosa, S. typhi and S. aureus respectively. The anti-microbial activity of Ocimum basilicum and Psidium guajava as demonstrated in this study raises hopes of their potentials as sources of medication against a wide range of diseases when used individually rather than in their combination.

Keywords: Antibacterial activities; ocimum basilicum; psidium guajava; bacteria

International Journal of Natural and Applied Sciences Vol. 2 (3) 2006: pp 214-218