Antimycobacterial assay
The antimycobacterial activity was performed using the
microplate Alamar blue assay (Collins & Franzblau, 1997).
Briefly, 100 mL of the test solution in a Middlebrook 7H9
medium was mixed with 100 mL of the same medium
containing 105 CFUmL1 of Mycobacterium tuberculosis
H37Ra to give a final concentration of fungal extract of
200 mgmL1 in each microplate well. After incubation at
37 1C for 7 days, 20 mL of Alamar blue was added to the
control well. If the dye turned pink, indicating bacterial
growth, the dye was then added to all the remaining wells.
Growth or no growth was determined on the following day
using fluorescence spectroscopy. Active extracts were retested
at lower doubling dilution concentrations to determine
the minimum inhibitory concentrations (MICs).
Standard drugs rifampin, isoniazid and kanamycin gave
MICs of 0.0023, 0.1, and 2.5 mgmL1, respectively, which
are within the acceptable ranges using this method.