The use of natural product scaffolds as leads in the search for trypanothione reductase inhibitors

Abstract

Twenty-three heterocyclic compounds were evaluated for their potential as trypanothione reductase inhibitors. As a result, the harmaline, 10-thiaisoalloxazine, and aspidospermine frameworks were identified as the basis of inhibitors of Trypanosoma cruzi trypanothione reductase. Two new compounds showed moderately strong, linear competitive inhibition, namely N, N-dimethyl- N-[3-(7-methoxy-1-methyl-3,4-dihydro-9 H-β-carbolin-9-yl)propyl]amine ( 15) and 1,3-bis[3-(dimethylamino)propyl]-1,5-dihydro-2 H-pyrimido[4,5- b][1,4]benzothiazine-2,4(3 H)-dione ( 21), with K i values of 35.1 ± 3.5 μM and 26.9 ± 1.9 μM, respectively. Aspidospermine ( 25) inhibited T. cruzi TryR with a K i of 64.6 ± 6.2 μM. None of the compounds inhibited glutathione reductase. Their toxicity toward promastigotes of Leishmania amazonensis was assessed.