Abstract In order to overcome the challenges of discovering new antiprotozoal drugs, we synthesized a new class of hybrids based on S-allylCysteine Ester/Caffeic Acid Amide and evaluated four of them against Trypanosoma cruzi and Plasmodium falciparum. Hybrid 6 exhibited good activity on T. cruzi with an EC50 value of 5.45 µM, whereas hybrid 3 was active over P. falciparum with an EC50 of 18.08 µM. All hybrids displayed a good selectivity index on P. falciparum. Molecular docking computations indicated that several hybrids have good binding affinities towards the protozoa related enzymes (Cruzipain or Falcipain-2) when compared against current inhibitors. In silico studies showed that conjugates 1-3 and 6 fulfilled optimal ADME characteristics, suggesting them as safe alternatives for oral treatment of protozoal infections.

ABSTRACT A set of methylimidazolium-furanchalcone hybrids and 1-alkyl-3-methylimidazolium salts were tested in order to find their antimicrobial activity against five gram positive bacteria, two gram negative bacteria and three fungi. In the series of 1-alkyl-3-methylimidazolium salts, compounds 4 and 7 were the most active compounds against S. mutans and F. oxysporum, respectively (MIC value of 3.0 and 6.7 mM, respectively). In addition, among the hybrid molecules, compound 10 exhibited the highest activity against F. solani (MIC50 = 14.3 mM) followed by hybrid 11 (MIC50 = 14.5 mM), which was also the most active against S. aureus, S. mutans (MIC50 = 14.6, 18.7 mM, respectively). The activity of these hybrids was even better with regard to the lead compounds (furanchalcone, methylimidazole or the mixture). In the structure-activity relationship there was observed higher bioactivity when the alkyl linker had eigth carbon atoms. This was then supported by the in silico study which displayed a strong relationship between the length of the alkyl chain on N and the biological activity. The results highlight the importance of these derivatives (1-alkyl-3-methylimidazolium salts) and hybrids (methylimidazolium-furanchalcone) as potential antimicrobial agents.