Design, Synthesis and Biological Evaluation of 7-arylbenzo[c]acridine-5,6-diones as Potential Anti-Leishmanial and Anti-trypanosomal Agents

Background: Leishmaniasis is endemic in 98 countries and is closely associated with poverty. On the basis of current evidence, it may be safely suggested that over time Leishmania spp. have evolved coexistence in different macrophage types and developed adaptations in order to ensure their intracellular survival. Considering new drugs, the need of the hour the present study deals with the synthesis of novel compounds of biological importance based on naturally occurring scaffolds. Objective: Synthesis, anti-leishmanial and anti-trypanosomal activities of a series of thirty three (eighteen newly synthesized and fifteen previously reported) 7-arylbenzo[c]acridine-5,6-diones. Method: A series of thirty-three 7-arylbenzo[c]acridine-5,6-diones was designed and synthesized. The anti-leishmanial and anti-trypanosomal activities of the newly synthesized compounds were done. Results: Seven compounds (14, 17, 19, 26, 27, 38 and 39) were found to exhibit excellent antiparasitic activities. Compound 14 was identified as the most potent compound against L. donovani promastigotes while compound 27 showed most significant inhibition activity against amastigotes. Compounds 14 and 27 showed remarkable inhibitory activity with IC50 values of 0.38 and 0.53 μM, respectively, when tested in human macrophage cell line (THP) infected with L. donovani amastigotes. Against trypanomastigotes, six compounds (15, 17, 19, 25, 26 and 43) demonstrated remarkable inhibition. Conclusion: Compound 19 was found to be the best anti-trypanosomal agent and showed 300-fold superior inhibitory activity to that of the standard drug DFMO. Significant anti-leishmanial and anti-trypanosomal activities combined with the non-cytotoxic profile presents 7-arylbenzo[c]acridine- 5,6-diones as new candidates with therapeutic potential in the treatment of parasitic diseases.