RESUMO
Antimicrobial activities have previously been described by traditional Eastern medicine in Chilopoda body extracts, but until now no bioactive peptides have been described. In this study, a novel antimicrobial peptide, lacrain, was isolated from the body extract of the Brazilian Chilopoda Scolopendra viridicornis. The peptide was isolated by reverse-phase high-performance liquid chromatography (RP-HPLC). Its activity was tested using a liquid growth inhibition assay and the peptide was characterised using mass spectrometry. Lacrain has a sequence composed of eight amino acid residues and a molecular mass of 925.5 Da. A synthetic peptide of the native lacrain had identical characteristics to those of the isolated material, confirming its sequence. The synthetic peptide was active only against Gram-negative bacteria, showing strong bactericidal activity. Moreover, the peptide did not present haemolytic activity against human erythrocytes. Lacrain represents a novel molecule with powerful antibacterial activity that could be used as a new template for the development of drugs against clinically resistant bacterial strains.
Assuntos
Anti-Infecciosos/farmacologia , Peptídeos Catiônicos Antimicrobianos/farmacologia , Artrópodes/química , Extratos Celulares/farmacologia , Adulto , Animais , Anti-Infecciosos/química , Anti-Infecciosos/isolamento & purificação , Peptídeos Catiônicos Antimicrobianos/química , Peptídeos Catiônicos Antimicrobianos/genética , Peptídeos Catiônicos Antimicrobianos/isolamento & purificação , Bactérias/efeitos dos fármacos , Brasil , Extratos Celulares/isolamento & purificação , Cromatografia Líquida de Alta Pressão , Cromatografia de Fase Reversa , Eritrócitos/efeitos dos fármacos , Fungos/efeitos dos fármacos , Hemólise , Humanos , Testes de Sensibilidade Microbiana , Peso Molecular , Análise de Sequência de ProteínaRESUMO
Antifungal and antibacterial activities were detected in the hemolymph and gut contents of the cattle tick, Boophilus microplus. A peptide with antibacterial activity from the tick gut contents was purified to homogeneity by reversed-phase chromatography. The molecular mass of the purified peptide was 3,205.7 Da, measured by matrix-assisted laser desorption/ionization mass spectrometry. The amino acid sequence was obtained by Edman degradation and showed that the peptide was identical to a fragment of the bovine alpha-hemoglobin. A synthetic peptide based on the sequence obtained showed characterization data identical to those of the isolated material, confirming its structure. The synthetic peptide was active in micromolar concentrations against Gram-positive bacteria and fungi. These data led us to conclude that the antibacterial activity detected in tick gut contents is the result of enzymatic processing of a host protein, hemoglobin. This activity may be used by ticks as a defense against microorganisms.
