Fig. 2.

Potency of drugs targeting the cyt-bc₁:aa₃ against M. ulcerans. a Growth inhibitory activity of Q203 and bedaquiline (BDQ) against classical M. ulcerans clinical isolates from Africa (blue symbols) and Australia (red symbols) replicating in culture broth medium using a resazurin-based assay. Data are expressed as the mean ± s.d. of triplicates for each concentration. b Growth inhibitory activity (MIC₅₀) of Q203 and BDQ against classical strains from African and Australian origin, and against ancestral strains from Japanese origin. MIC₅₀ values are the average of three strains, each tested in duplicate. c Growth inhibitory activity of Q203 and bedaquiline (BDQ) against the classical strain S1013 (red symbols) and the ancestral strain S1325 (blue symbols) replicating in culture broth medium using a turbidity-based assay. Data are expressed as the mean ± s.d. of triplicates for each concentration. The red dotted line shows the bottom plateau for the dose–response curve for bedaquiline and Q203 against the classical strain; the blue dotted line shows the bottom plateau of the dose–response curve for Q203 against the ancestral strain. d Bactericidal potency of Q203 against the classical strain S1013 replicating in culture broth medium. Q203 was tested at a concentration of 1, 4, and 16 nM in triplicate and repeated once. The dotted line represents the limit of detection. **P value <0.001, using the Student's t test, between the untreated control group (1% DMSO) and Q203 at either 1, 4 or 16 nM