The emergence of multidrug-resistant strains of Mycobacterium tuberculosis underscores the need of
continuous developments on new and efficient methods to determine the susceptibility of isolates of M.
tuberculosis in the search for novel antimicrobial agents. Natural products constitute an important source
of new drugs, but design and implementation of antimycobacterial susceptibility testing methods are
necessary for evaluate the different extracts and compounds. A number of biological assay methodologies
are in current use, ranging from the classical disk diffusion and broth dilution assay format, to
radiorespirometric (BACTEC), dye-based, and fluorescent/luminescence reporter assays. This review
presents an analysis on the in vitro susceptibility testing methods developed for determinate antitubercular
activity in natural products and related compounds (semi-synthetic natural products and natural productsderived
compounds) and the criteria to select the adequate method for determination of biological activity
of new natural products.
