Indolylquinoline derivatives are cytotoxic to Leishmania donovani promastigotes and amastigotes in vitro and are effective in treating murine visceral leishmaniasis

A wide variety of biologically active compounds contain indole and quinoline nuclei. Some novel indolylquinoline derivatives were synthesized from indole by Friedel-Crafts acylation reaction. Out of the four derivatives tested, 2-(2"-acetamidobenzyl)-3-(3'-indolylquinoline) (C) had no effect on the promastigotes or amastigotes of Leishmania donovani in vitro. The remaining three analogues, 2-(2"-dichloroacetamidobenzyl)-3-(3'-indolylquinoline) (A), 2-(2"-chloroacetamidobenzyl)-3-(3'-indolylquinoline) (B), and 2-(2"-aminobenzyl)-3-(3'-indolylquinoline) (D), inhibited the growth of L. donovani promastigotes in vitro and were cytotoxic to both the promastigote and amastigote forms of the parasite. These three derivatives were also effective in eliminating L. donovani amastigotes from BALB/c mouse peritoneal macrophages in vitro. One indolylquinoline derivative [A] was used to treat established visceral leishmaniasis in BALB/c mice. This compound was significantly more effective than sodium antimony gluconate (SAG) in reducing the splenic parasite load at a much lower concentration (5% of SAG). Our results suggest that indolylquinoline derivatives may be exploited as antileishmanial agents.