In vivo activity of compound 1, as shown in an acute monotherapy model (A) and a chronic combination therapy model (B, C). For the acute model, mice were infected with 3.2 log10 CFU by the aerosol route and treatment was initiated on day 1 after infection. For the chronic model, mice were infected with 2.0 log10 CFU by the aerosol route and treatment was initiated 28 days after infection. CFU in the lungs were determined after 4 weeks (A) or 8 weeks (B) of treatment. UT, untreated; E, ethambutol (100 mg/kg); RIF, rifampin (10 mg/kg); INH, isoniazid (10 mg/kg); 1_50, compound 1 at 50 mg/kg. All treatment was daily, 5 days a week. Data are shown as mean ± SD (*, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001 by one-way ANOVA and Tukey’s multiple-comparison test). (C) Bliss independence model demonstrated synergistic effects of the combination of 1 and rifampin and INH and rifampin (unpaired t test applied).