title: Antimicrobial activity and mechanism of action of a thionin-like peptide from Capsicum annuum fruits and combinatorial treatment with fluconazole against Fusarium solani.
abstract: Many Fusarium species are able to cause severe infections in plants as well as in animals and humans. Therefore, the discovery of new antifungal agents is of paramount importance. CaThi belongs to the thionins, which are cationic peptides with low molecular weights (∼5 kDa) that have toxic effects against various microorganisms. Herein, we study the mechanism of action of CaThi and its combinatory effect with fluconazole (FLC) against Fusarium solani. The mechanism of action of CaThi was studied by growth inhibition, viability, plasma membrane permeabilization, ROS induction, caspase activation, localization, and DNA binding capability, as assessed with Sytox green, DAB, FITC-VAD-FMK, CaThi-FITC, and gel shift assays. The combinatory effect of CaThi and FLC was assessed using a growth inhibition assay. Our results demonstrated that CaThi present a dose dependent activity and at the higher used concentration (50 µg mL-1) inhibits 83% of F. solani growth, prevents the formation of hyphae, permeabilizes membranes, induces endogenous H2O2, activates caspases, and localizes intracellularly. CaThi combined with FLC, at concentrations that alone do not inhibit F. solani, result in 100% death of F. solani when combined. The data presented in this study demonstrate that CaThi causes death of F. solani via apoptosis; an intracellular target may also be involved. Combined treatment using CaThi and FLC is a strong candidate for studies aimed at improved targeting of F. solani. This strategy is of particular interest because it minimizes selection of resistant microorganisms.
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio De Janeiro, 28013-602, Brazil.
authors.forename: Gabriel B
authors.initials: GB
authors.lastname: Taveira
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio De Janeiro, 28013-602, Brazil.
authors.forename: Érica O
authors.initials: ÉO
authors.lastname: Mello
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio De Janeiro, 28013-602, Brazil.
authors.forename: André O
authors.initials: AO
authors.lastname: Carvalho
authors.affiliation: Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata-CONICET, Funes 3250, Mar del Plata, 7600, Argentina.
authors.forename: Mariana
authors.initials: M
authors.lastname: Regente
authors.affiliation: Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata-CONICET, Funes 3250, Mar del Plata, 7600, Argentina.
authors.forename: Marcela
authors.initials: M
authors.lastname: Pinedo
authors.affiliation: Instituto de Investigaciones Biológicas, Universidad Nacional de Mar del Plata-CONICET, Funes 3250, Mar del Plata, 7600, Argentina.
authors.forename: Laura
authors.initials: L
authors.lastname: de La Canal
authors.affiliation: Laboratório de Melhoramento Genético Vegetal, Centro de Ciências e Tecnologias Agropecuárias, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio De Janeiro, 28013-602, Brazil.
authors.forename: Rosana
authors.initials: R
authors.lastname: Rodrigues
authors.affiliation: Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadual do Norte Fluminense, Campos dos Goytacazes, Rio De Janeiro, 28013-602, Brazil.
authors.forename: Valdirene M
authors.initials: VM
authors.lastname: Gomes
mesh_terms: D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000494:pharmacology*; D002212:Capsicum / Q000737:chemistry; D002462:Cell Membrane / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D015725:Fluconazole / Q000494:pharmacology*; D005638:Fruit / Q000737:chemistry; D005670:Fusarium / Q000187:drug effects / Q000472:pathogenicity; D006801:Humans; D025301:Hyphae / Q000187:drug effects / Q000472:pathogenicity; D054809:Thionins / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000935:Antifungal Agents; D023181:Antimicrobial Cationic Peptides; D054809:Thionins; D015725:Fluconazole
keywords: antimicrobial peptides; fungi; membrane permeability; synergism