Prospecção de peptídeos bacterianos com atividade anti-Leishmania

Abstract

Antimicrobial peptides are a diverse group of bioactive molecules naturally produced by a variety of prokaryotic and eukaryotic organisms with antimicrobial activity. Brazil represents the highest incidence country of leishmaniasis in the American continent, so the objective of this work was prospect bacteria peptides with anti-Leishmania activity. A total of 466 bacterial samples were used to produce extracellular crude extracts to evaluate antimicrobial activity against bacterial cells (Gram-positive and negative bacteria), yeast (Candida sp) and Leishmania sp. and characterize antimicrobial spectrum of action. Only Leishmania activity extracts were submitted to protein precipitation and tested to peptides production. The producing sample were characterized by genetic, morphologic and metabolic tests, and the best physiological moment of peptides production was determinate. The results showed that 222 extracts had bacterial activity, 05 extracts had Candida activity, and 20 extracts had Leishmania activity, summarizing 51 % of positive samples to antimicrobial substances production. For promastigote Leishmania activity, 20 mg/ mL extracts showed inhibition values by MTT method of 33 % in L. braziliensis and L. chagasi, 30.7 % in L. major and 29 % in L. amazonensis. The amastigote forms viability was observed for 40 mg/mL crude extract of Staphylococcus edpidermidis (CGP360), with a reduction value of 60 %. And this same extract did not have toxicity to peritoneal macrophages, an important result for new drugs of systemic use. Concerning the characterization of the producing sample, it was observed that the production of the antagonistic substance with the highest anti-Leishmania activity occurred in TSB and BHI media extracts coming from stationary phase. Additional studies should be performed to better understand the interaction of bacterial extracts in Leishmania species, but the results described in this paper are promising and unpublished in the scientific literature.