Effect of piplartine and cinnamides on Leishmania amazonensis, Plasmodium falciparum and on peritoneal cells of Swiss mice

Abstract

Context: Plants of the Piperaceae family produce piplartine that was used to synthesize the cinnamides. Objective: To assess the effects of piplartine (1) and cinnamides (2-5) against the protozoa responsible for malaria and leishmaniasis, and peritoneal cells of Swiss mice. Materials and methods: Cultures of Leishmania amazonensis, Plasmodium falciparum-infected erythrocytes, and peritoneal cells were incubated, in triplicate, with different concentrations of the compounds (0 to 256 µg/mL). The inhibitory concentration (IC50) in L. amazonensis and cytotoxic concentration (CC50) in peritoneal cell were assessed by the MTT method after 6 h of incubation, while the IC50 for P. falciparuminfected erythrocytes was determined by optical microscopy after 48 or 72 h of incubation; the Selectivity Index (SI) was calculated by CC50/IC50. Results: All compounds inhibited the growth of microorganisms, being more effective against P. falciparum after 72 h of incubation, especially for the compounds 1 (IC50=3.2 µg/mL) and 5 (IC50=6.6 µg/mL), than to L. amazonensis (compound 1=179.0 µg/mL; compound 5=106.0 µg/mL). Despite all compounds reducing the viability of peritoneal cells, the SI were <10 to L. amazonensis, whereas in the cultures of P. falciparum the SI >10 for the piplartine (>37.4) and cinnamides 4 (>10.7) and 5 (=38.4). Discussion and conclusion: The potential of piplartine and cinnamides 4 and 5 in the treatment of malaria suggest further pre-clinical studies to evaluate their effects in murine malaria and to determine their mechanisms in cells of the immune system.