Figure 4. Semapimod is a non-toxic antibiotic effective against metabolically dormant bacteria.

A) Semapimod MIC against Ec BW in LB, or in the presence of 0.55 mM BSA or 10% fetal-bovine serum (FBS). Data are representative of two biological replicates; error bars represent s.e.m. B) Killing of Ec BW in low to high nutrient conditions. Light red to dark red shading indicates increasing nutrient content. C) Survival versus intracellular ATP for concentrations of semapimod at 2X MIC or greater. Light blue to dark blue shading indicates increasing semapimod concentration. D) Metabolism dependence of semapimod. Linear regression was performed on the survival versus ATP data, at every antibiotic concentration, and the negative slope was taken as the metabolism-dependence value. Data for known antibiotics are reproduced from Zheng et al., 2020¹⁶ and shown here for comparison. Light blue to dark blue shading indicates increasing antibiotic concentration. Data are representative of two biological replicates; error bars indicate s.e.m. E) Semapimod killing activity against stationary-phase Ec BW, Ec 25922, Kp, Pa, and Ab. Shown is the mean of two biological replicates; error bars represent s.e.m.