Antileishmanial Activity Screening

Promastigote forms of L. amazonensis in the log growth phase (10^e6 parasites/mL) were added to 96-well plates and incubated in sextuplicate with the test samples (0.25–10.0 µg/mL). The microplates were incubated at 26 °C for 72 h. Cell viability was assessed by adding 5 mg/mL of MTT ([3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] (Sigma-Aldrich^® SP/Brazil) [20 ]. Results were expressed as the half-maximal inhibitory concentration (IC₅₀) calculated by a nonlinear dose–response regression curve using the statistical program GraphPad PRISM 5.0. Pentamidine (Sigma-Aldrich ^® SP/Brazil; 0.25–10 µg/mL) was used as a positive control, and pure Schneider culture medium was used as a negative control.