title: Melanin protects Paracoccidioides brasiliensis from the effects of antimicrobial photodynamic inhibition and antifungal drugs.
abstract: Paracoccidioidomycosis (PCM) is a public health concern in Latin America and South America that when not correctly treated can lead to patient death. In this study, the influence of melanin produced by Paracoccidioides spp. on the effects of treatment with antimicrobial photodynamic inhibition (aPI) and antifungal drugs was evaluated. aPI was performed using toluidine blue (TBO) as a photosensitizer and a 630-nm light-emitting diode (LED) light. The antifungals tested were itraconazole and amphotericin B. We evaluated the effects of each approach, aPI or antifungals, against nonmelanized and melanized yeast cells by performing susceptibility tests and by quantifying oxidative and nitrosative bursts during the experiments. aPI reduced nonmelanized cells by 3.0 log units and melanized cells by 1.3 log units. The results showed that melanization protects the fungal cell, probably by acting as a scavenger of nitric oxide and reactive oxygen species, but not of peroxynitrite. Melanin also increased the MICs of itraconazole and amphotericin B, and the drugs were fungicidal for nonmelanized and fungistatic for melanized yeast cells. Our study shows that melanin production by Paracoccidioides yeast cells serves a protective function during aPI and treatment with itraconazole and amphotericin B. The results suggest that melanin binds to the drugs, changing their antifungal activities, and also acts as a scavenger of reactive oxygen species and nitric oxide, but not of peroxynitrite, indicating that peroxynitrite is the main radical that is responsible for fungal death after aPI.
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Ludmila Matos
authors.initials: LM
authors.lastname: Baltazar
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Silvia Maria Cordeiro
authors.initials: SM
authors.lastname: Werneck
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil Departamento de Engenharia Mecânica, Laboratório de Bioengenharia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil Universidade de Itaúna, Itaúna, Minas Gerais, Brazil.
authors.forename: Betânia Maria
authors.initials: BM
authors.lastname: Soares
authors.affiliation: Departamento de Engenharia Mecânica, Laboratório de Bioengenharia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Marcus Vinicius L
authors.initials: MV
authors.lastname: Ferreira
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Danielle G
authors.initials: DG
authors.lastname: Souza
authors.affiliation: Departamento de Engenharia Mecânica, Laboratório de Bioengenharia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Marcos
authors.initials: M
authors.lastname: Pinotti
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Daniel Assis
authors.initials: DA
authors.lastname: Santos
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil pscisalp@icb.ufmg.br.
authors.forename: Patrícia Silva
authors.initials: PS
authors.lastname: Cisalpino
mesh_terms: D000666:Amphotericin B / Q000737:chemistry / Q000494:pharmacology; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology*; D025141:Drug Resistance, Fungal / Q000187:drug effects; D016166:Free Radical Scavengers / Q000494:pharmacology; D017964:Itraconazole / Q000737:chemistry / Q000494:pharmacology; D042845:Laccase / Q000378:metabolism; D007980:Levodopa / Q000494:pharmacology; D008543:Melanins / Q000737:chemistry / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009569:Nitric Oxide / Q000378:metabolism; D010228:Paracoccidioides / Q000187:drug effects*; D030421:Peroxynitrous Acid / Q000378:metabolism; D010778:Photochemotherapy; D017382:Reactive Oxygen Species / Q000378:metabolism; D016897:Respiratory Burst / Q000187:drug effects
chemical_list: D000935:Antifungal Agents; D016166:Free Radical Scavengers; D008543:Melanins; D017382:Reactive Oxygen Species; D030421:Peroxynitrous Acid; D017964:Itraconazole; D009569:Nitric Oxide; D007980:Levodopa; D000666:Amphotericin B; D042845:Laccase