Antimycotic and cytotoxicological potentials of Acacia mearnsii de wild. stem bark extract: In vitro assessment

Despite using antimycotic drugs in the treatment of dermatomycoses as an age long practice, the fungicidal activities of indigenous plants on spores of dermatophytes from germinating in vitro need to be investigated further. In this study, methanol extract of Acacia mearnsii was assessed for its antifungal activity against dermatophytic pathogenic fungi by agar diffusion and broth dilution methods. The cytotoxicity activity of the extract was determined by the brine shrimp lethality assay. The study showed that the mean ± standard deviation of the inhibition zones ranged between 13 and 24 ± 0.58 mg/ml and the activity of the extract was concentration dependent. While the minimum inhibitory concentration (MIC) was 0.3125 - 2.5 mg/ml, the minimum fungicidal concentration (MFC) values ranged between 0.3125 mg/ml and 5 mg/ml. The susceptibility of the yeast to the extract was more than those of the molds. The MIC of the yeasts ranged between 0.3125 and 1.25 mg/ml while those of the molds ranged between 0.625 and 2.5 mg/ml. The mechanism of antibiosis showed that the extract was 7.69% fungistatic and 92.31% fungicidal wielding more killing effects on the fungi than potentiating their growth. The cytotoxicity assay showed that the crude methanolic extract with the LC50 being 101.59 µg/ml was pharmacologically active and nontoxic (LC50 > 100 μg/ml). The antifungal activity of this plant can be exploited as an alternative or complementary means of treating fungal infections to eliminate fungal spread. The study further justified the folkloric use of A. mearnsii in the treatment of a variety of microbial infections.