Antibacterial and Antifungal Activity of Acalypha wilkesiana

Abstract

The antimicrobial activity of the leave of Acalypha wilkesiana methanolic extract and its four derivative fractions were determined on human pathogenic bacteria namely strains of Staphylococcus aureus, Streptococcus pyogenes, Enterococcus faecalis, Pseudomonas aeruginosa, Proteus vulgaris and Escherichia coli and fungi; Aspergillus niger, A. flavus, A. carbonerium, Trichophyton mentagrophytes and Candida albicans. Methanolic extract (200 mg/ml) and its fractions were tested on the bacteria and fungi using the disc diffusion method. In vitro antibacterial and antifungal activity were screened by using Mueller Hinton Agar (MHA) and Potato Dextrose Agar (PDA) respectively. The minimum inhibitory concentration for the bacteria and fungi were also determined. Results showed broad spectrum antimicrobial activity against the Gram-negative and Gram-positive bacteria but same cannot be said about its activity against the fungi. The ethyl acetate fraction inhibited the growth of more bacteria and fungi compared to the other fractions; however, Research Article European Journal of Medicinal Plants, 3(1): 52-64, 2013 53 the aqueous extract was more effective on the bacteria isolates as it showed the lowest MIC for more bacteria compared to the other fractions. The extract and its fractions were active against bacteria which some standard antibiotics were not able to inhibit. Methanolic extract of A. wilkesiana leaves and its fractions showed a better antibacterial activity than antifungal activity. The fact that the plant was active against both clinical and laboratory isolates is an indication that it can be a source of very potent antibiotic substances that can be used against drug resistant microorganisms. The search for new drugs to counter the challenges posed by resistant strains of bacteria and some fungi might have started yielding results as the investigation of this plant has demonstrated enormous therapeutic potential.