5-Nitroisatin-derived thiosemicarbazones: potential antileishmanial agents

A series of 29 previously reported N-4-substituted 5-nitroisatin-3-thiosemicarbazones 2-30 has been screened for leishmanicidal potential. Compounds 2-4, 7, 8, 10-13, 15-19, 21, 23, 24, 26, 28 and 30 exhibited good to excellent antileishmanial activities with IC50 values ranging from 0.44 +/- 0.02 to 32.38 +/- 0.66 mu g/mL. Of these, 5, 7, 19 and 28 proved to be the most active antileishmanial agents, displaying activities with IC50 values 1.78 +/- 0.35, 0.44 +/- 0.02, 1.91 +/- 0.04 and 4.28 +/- 0.75 mu g/mL, respectively, which were even better than the standard drug, pentamidine (IC50 5.09 +/- 0.04 mu g/mL). This study presents the first example of exhibition of leishmanicidal potential by isatin-thiosemicarbazones and as such furnishes a solid basis for further research on these compounds to develop more potent antileishmanial agents.