Synthesis, biological evaluation and structure-activity relationships of N-benzoyl-2-hydroxybenzamides as agents active against P. falciparum (K1 strain), Trypanosomes, and Leishmania

In our efforts to identify novel chemical scaffolds for the development of new anti-protozoal drugs, a compound library was screened against T. gondii tachyzoites with activity discovered for N-(4-ethylbenzoyl)-2-hydroxybenzamide 1a against T. gondii as described elsewhere.1 Synthesis of a compound set was guided by T. gondii SAR with 1r found to be superior for T. gondii, also active against Thai and Sierra Leone strains of P. falciparum, and with superior ADMET properties as described elsewhere.1 Herein, synthesis methods and details of the chemical analysis of the compounds in this series are described. Further, this series of N-benzoyl-2-hydroxybenzamides was re-purposed for testing against four other protozoan parasites: T. b. rhodesiense, T. cruzi, L. donovani, and P. falciparum (K1 isolate). Structure-activity analyses led to the identification of compounds in this set with excellent anti-leishmanial activity (compound 1d). Overall, compound 1r was the best and had activity 21-fold superior to that of the standard anti-malarial drug chloroquine against the K1 P. falciparum isolate