title: Isolation, characterization and mechanism of action of an antimicrobial peptide from Lecythis pisonis seeds with inhibitory activity against Candida albicans.
abstract: Antimicrobial peptides (AMPs) are produced by a range of organisms as a first line of defense against invaders or competitors. Owing to their broad antimicrobial activity, AMPs have attracted attention as a potential source of chemotherapeutic drugs. The increasing prevalence of infections caused by Candida species as opportunistic pathogens in immunocompromised patients requires new drugs. Lecythis pisonis is a Lecythydaceae tree that grows in Brazil. The AMPs produced by this tree have not been described previously. We describe the isolation of 12 fractions enriched in peptides from L. pisonis seeds. Of the 12 fractions, at 10 μg/ml, the F4 fraction had the strongest growth inhibitory effect (53.7%) in Candida albicans, in addition to a loss of viability of 94.9%. The F4 fraction was separated into seven sub-fractions by reversed-phase chromatography. The F4.7' fraction had the strongest activity at 10 μg/ml, inhibiting C. albicans growth by 38.5% and a 69.3% loss of viability. The peptide in F4.7' was sequenced and was found to be similar to plant defensins. For this reason, the peptide was named L. pisonis defensin 1 (Lp-Def1). The mechanism of action that is responsible for C. albicans inhibition by Lp-Def1 includes a slight increase of reactive oxygen species induction and a significant loss of mitochondrial function. The results described here support the future development of plant defensins, specifically Lp-Def1, as new therapeutic substances against fungi, especially C. albicans.
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil.
authors.forename: Maria Eliza Brambila
authors.initials: ME
authors.lastname: Vieira
authors.affiliation: Laboratório de Toxinas Vegetais, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Fortaleza, Brazil.
authors.forename: Ilka Maria
authors.initials: IM
authors.lastname: Vasconcelos
authors.affiliation: Laboratório de Química e Função de Proteínas e Peptídeos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil.
authors.forename: Olga Lima Tavares
authors.initials: OL
authors.lastname: Machado
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil.
authors.forename: Valdirene Moreira
authors.initials: VM
authors.lastname: Gomes
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, RJ 28013-602, Brazil andre@uenf.br.
authors.forename: André de Oliveira
authors.initials: Ade O
authors.lastname: Carvalho
mesh_terms: D000935:Antifungal Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D002176:Candida albicans / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D056148:Chromatography, Reverse-Phase; D004591:Electrophoresis, Polyacrylamide Gel; D019684:Magnoliopsida / Q000196:embryology*; D008826:Microbial Sensitivity Tests; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012639:Seeds / Q000737:chemistry*
chemical_list: D000935:Antifungal Agents; D010455:Peptides; D017382:Reactive Oxygen Species
keywords: candidacidal; membrane permeabilization; mitochondria functionality loss; reactive oxygen species