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

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 (IC) in L. amazonensis and cytotoxic concentration (CC) in peritoneal cell were assessed by the MTT method after 6 h of incubation, while the IC for P. falciparum-infected erythrocytes was determined by optical microscopy after 48 or 72 h of incubation; the Selectivity Index (SI) was calculated by CC/IC.

Results: All compounds inhibited the growth of microorganisms, being more effective against P. falciparum after 72 h of incubation, especially for the compounds 1 (IC = 3.2 μg/mL) and 5 (IC = 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.