Antimicrobial activity of various extracts of Plectranthus ambionicus and Phyllanthus amarus

Abstract

Hexane, chloroform, ethyl acetate and methanol extracts of leaves of Plectranthus ambionicus and  Phyllanthus amarus were screened for their antimicrobial activity against human pathogenic bacterial and fungal strains. Antimicrobial activity was carried out by disc diffusion method, determination of minimum inhibitory concentrations (MIC), minimum bactericidal concentrations (MBC) and minimum fungicidal concentrations (MFC) against four strains of Gram positive bacteria, three strains of Gram negative bacteria and three species of fungi. The antimicrobial activity of various extracts of Plectranthus ambionicus and Phyllanthus amarus showed varied levels of antimicrobial activity against the studied bacterial and fungal pathogens. The mean zone of inhibition produced by all the tested extracts ranged from 7.0 ± 0.50 mm to 29.5 ± 0.50 mm. The MIC, MBC and MFC values were between 15.62 and 1000 μg/mL. The ethyl acetate extract of Plectranthus ambionicus showed good antimicrobial activity with the highest mean zone of inhibition (29.5±0.5 mm), lowest MIC (15.62 μg/mL) and MBC (31.25 μg/mL) values followed by ethyl acetate extract of Phyllanthus amarus(23.6±0.50 mm; MIC=62.5; MBC=125 μg/mL) against Aspergillus fumigates.