Antibacterial activity of selected Cameroonian dietary spices ethno-medically used against strains of Mycobacterium tuberculosis

Ethnopharmacological relevance: Tuberculosis (TB) is considered as a re-emerging disease and one of the most important public health problems worldwide. The use or (in most cases) misuse of existint antituberculosis drugs over the years has led to an increasing prevalence of resistant strains, establishing an urgent need to search for new effective agents. Spices are largely used ethno-medically across Africa. Aim of the study: The present study aimed to evaluate the in vitro antimycobacterial activities of a total of 20 methanol crude extracts prepared from 20 Cameroonian dietary spices for their ability to inhibit the growth of or kill Mycobacterium tuberculosis strains H(37)Rv (ATCC 27294) and H37Ra (ATCC 25177). Materials and methods: The antituberculosis screening was performed using the Microplate Alamar Blue Assay (MABA) method to determine the minimum inhibitory concentration (MIC) and the minimum mycobactericidal concentration (MBC). Results: Fifteen (15) plant extracts out of 20 showed varied levels of antimycobacterial activity against the strains M. tuberculosis H(37)Rv and H37Ra, with MICs in the range of 2.048-.0.016 mg/ml. The extract of Echinops giganteus exhibited the most significant activity with a MIC value of 32 mu g/ml and 16 mu g/ml, respectively against H37Ra and H(37)Rv. To the best of our knowledge, the antimycobacterial activity of the tested spices has not been reported before and therefore our results can be evaluated as the first report about the antimycobacterial properties. Conclusions: The results of this study suggest that Echinops giganteus and Piper guineense could be important sources of bactericidal compounds against M. tuberculosis and could probably be promising candidates that can be further investigated. (C) 2012 Elsevier Ireland Ltd. All rights reserved.