Dados do Trabalho

Título

ANTILEISHMANIAL PEPTIDES: PLANNING, SYNTHESIS, CHEMICAL AND BIOLOGICAL CHARACTERIZATION OF THREE NEW SYNTHETIC PEPTIDES DIRECTED TO THE MCU (MITOCHONDRIAL CALCIUM UNIPORTER) MOLECULAR TARGET OF LEISHMANIA

Introdução

INTRODUCTION: Leishmaniasis is a highly prevalent neglected disease, endemic in 89 countries, which affects approximately 2 million worldwide. It is caused by “Leishmania spp”, transmitted by sandflies' bite. Therapeutic treatment has several drawbacks, thus, the design of new leishmanicidal, based on essential targets, proves to be an important strategy. In literature, calcium is associated with survival and infectivity, which makes this signaling pathway attractive. Despite other structures involved in calcium homeostasis, genetic studies revealed that MCU complex (Mitochondrial Calcium Uniporter) plays an essential role in “Trypanosoma brucei” but not in “Trypanosoma cruzi” and there is no evidence to “Leishmania”. Thus, to better understand the MCU as a possible drug target, we designed by homology the structure of L.mexicana’s MCU and, using molecular anchoring, we delineated peptides to selectively block its filter (DIME).

Objetivo (s)

OBJECTIVES: Synthesis, chemical and biological characterization of three peptides on viability of  “Leishmania amazonensis”(L.a), “Trypanosoma brucei”(T.b), “Trypanosoma cruzi”(T.c) and macrophages derived from THP-1.

Material e Métodos

MATERIALS/METHODS: Solid phase peptide synthesis was done using Rink Amide resin, with protection and deprotection cycles. After cleavage, the purification and purity check was carried out by high performance liquid chromatography (HPLC). Molecular mass was confirmed by the spectrometer in positive electrospray mode, and structuration was test by circular dichroism in phosphate saline buffer (PBS) and different concentration of lysophosphatidylcholine (LPS) or 2,2,2-trifluoroethanol (TFE). Peptide´s IC50 was verified against T.b trypomastigotes and L.a promastigotes in cell viability assays.

Resultados e Conclusão

RESULTS: Three peptides AD2201, AD2303 and AD2306 were successfully synthesized, with purity higher than 95%, and with expected molecular mass. Circular dichroism revealed that they are not able to form structures in either PBS, LPS or TFE, dissociating any possible biological activity related to secondary structure. Until now, AD2201 showed low antiparasitic activity (IC50 >100 µm) for both L.a and T.b, whilst AD2203 showed interesting anti T.b activity (IC50=18,45µm). CONCLUSION: All peptides were obtained with high purity, AD2203 exhibited good anti T.b activity, as expected based on aforementioned genetics. Sequentially, apart from the future assays already outlined, others can be planned to confirm the mechanism of action.  

Palavras Chave

Antimicrobial Peptides; New Targets; Leishmaniasis; Calcium; mitochondrial calcium unipoter