In vitro activity of phospholipase ASubscript2/Subscript and of peptides from Emphasis Type="Italic"Crotalus durissus terrificus/Emphasis venom against amastigote and promastigote forms of Emphasis Type="Italic"Leishmania (L.) infantum chagasi/Emphasis

摘要

class="Heading">Background id="Par1" class="Para">American visceral leishmaniasis is caused by the intracellular parasite Leishmania (L.) infantum chagasi, and transmitted by the sand fly Lutzomyia longipalpis. Since treatment is based on classical chemotherapeutics with significant side effects, the search for new drugs remains the greatest global challenge. Thus, this in vitro study aimed to evaluate the leishmanicidal effect of Crotalus durissus terrificus venom fractions on promastigote and amastigote forms of Leishmania (L.) infantum chagasi. class="Heading">Methods id="Par2" class="Para">Phospholipase A₂ (PLA₂) and a pool of peptide fraction (3??kDa) were purified from Crotalus venom. Furthermore, promastigotes and peritoneal macrophages of mice infected by amastigotes were exposed to serial dilutions of the PLA₂ and peptides at intervals varying between 1.5625????g/mL and 200????g/mL. Both showed activity against promastigotes that varied according to the tested concentration and the time of incubation (24, 48 and 72??h). class="Heading">Results id="Par3" class="Para">MTT assay for promastigotes showed IC₅₀ of 52.07????g/mL for PLA₂ and 16.98????g/mL for the peptide fraction of the venom. The cytotoxicity assessment in peritoneal macrophages showed IC₅₀ of 98????g/mL and 16.98????g/mL for PLA₂ and peptide by MTT assay, respectively. In peritoneal macrophages infected by Leishmania (L.) infantum chagasi amastigotes, the PLA₂ stimulated growth of parasites, and at higher doses reduced growth by 23??%. The peptide fraction prevented 43??% of the intracellular parasite growth at a dose of 16.98????g/mL, demonstrating the toxicity of this dose to macrophages. Both fractions stimulated H₂O₂ production by macrophages but only PLA₂ was able to stimulate NO production. class="Heading">Conclusion id="Par4" class="Para">We have demonstrated the in vitro leishmanicidal activity of the PLA₂ and peptide fraction of Crotalus venom. The results encourage further studies to describe the metabolic pathways involved in cell death, as well as the prospecting of molecules with antiparasitic activity present in the peptide fraction of Crotalus durissus terrificus venom.