Antimicrobial Activity of the Methanol and Aqueous Leaf Extracts of <i>Emilia coccinea</i> (Sims) G. Don

Abstract

Assessment of the aqueous and methanol extracts of Emilia coccinea leaves was investigated in order to verify its claimed folkloric usage in treatment of microbial infections. Sensitivity tests for antimicrobial properties/activities of the leaf extracts were determined using Agar well diffusion method. Minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of extracts were also determined using doubling dilution and agar diffusion method respectively. Commercial antibiotics were used as positive reference standards to determine sensitivity of tested organisms. All test organisms (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Aspergillus niger, Penicillium notatum and Candida albicans) were found to be sensitive to both extracts. Methanol extract recorded highest mean inhibition diameter of 20.33±2.73mm against S. aureus. Aqueous extract had least mean inhibition diameter of 0.00±0.00mm against P. notatum. MIC values showed that methanol extract was more active than aqueous extract. MBC values for methanol extract varied between 5mg/ml – 25mg/ml as against 25mg/ml – 35mg/ml for aqueous extract. It was also observed that aqueous extract had no bactericidal action against P. aeruginosa. The results demonstrate that extracts of E. coccinea leaf has a broad spectrum of activity and can be a potential source of antimicrobial agents. Thus, the folkloric usage of this plant for the treatment of microbial diseases is justified.

Keywords: E. coccinea, Aqueous and Methanol extracts, Antimicrobial activity

Nig J. Biotech. Vol. 25 (2013) 37-45