Accessible and distinct decoquinate derivatives active against Mycobacterium tuberculosis and apicomplexan parasites

The quinolone decoquinate is coadministered with feed for treatment of parasites which cause coccidiosis in poultry. However, from a drug-development perspective, the biological activity is often not adequately exploited due to poor physicochemical properties. Here we convert decoquinate into N -alkyl quinolone amides that, in contrast to decoquinate, are active against the tuberculosis bacterium with MIC 90 values ranging from 1.4 to 3.64 µM, and quinoline O -carbamates active against apicomplexan parasites that cause malaria, toxoplasmosis, and neosporosis with IC 50 values of 0.32–1.5 nM for the best derivative. Uniquely for the TB-active amides, disruption of cell wall homoeostasis is identified as one target. With IC 50 values against fetal lung fibroblast cells of 40 to >100 μM, the derivatives are selective for the pathogens. Structures of the most active derivatives are determined by NMR spectroscopy and X-ray crystallography. Analogues lacking the decyl side chain of decoquinate are inactive. Decoquinate is a drug used in veterinary practice, which displays antimalarial activity in vitro but has poor bioavailability. Here, the authors convert decoquinate into more soluble amide and carbamate derivatives and assess their efficacy against tuberculosis bacteria and apicomplexan parasites.