title: Miltefosine is fungicidal to Paracoccidioides spp. yeast cells but subinhibitory concentrations induce melanisation.
abstract: Paracoccidioidomycosis (PCM) is a systemic mycosis caused by the dimorphic fungi Paracoccidioides spp. The duration of antifungal treatment ranges from months to years and relapses may nevertheless occur despite protracted therapy. Thus, there remains an urgent need for new therapeutic options. Miltefosine (MLT), an analogue of alkylphospholipids, has antifungal activity against species of yeast and filamentous fungi. The aim of this study was to evaluate the antifungal effects of MLT on the yeast forms of Paracoccidioides brasiliensis and Paracoccidioides lutzii. MLT demonstrated inhibitory activity from 0.12 to 1 µg/mL, which was similar to amphotericin B or the combination trimethoprim/sulfamethoxazole but was not more effective than itraconazole. The fungicidal activity of MLT occurred at concentrations ≥1 µg/mL. Ultrastructural alterations were observed following exposure of the fungus to a subinhibitory concentration of MLT, such as cytoplasmic membrane alteration, mitochondrial swelling, electron-lucent vacuole accumulation and increasing melanosome-like structures. Melanin production by yeasts following MLT exposure was confirmed by labelling with antibodies to melanin. In addition, the combination of a subinhibitory concentration of MLT and tricyclazole, an inhibitor of DHN-melanin biosynthesis, drastically reduced yeast viability. In conclusion, MLT had a fungicidal effect against both Paracoccidioides spp., and a subinhibitory concentration impacted melanogenesis. These findings suggest that additional investigations should be pursued to establish a role for MLT in the treatment of PCM.
authors.affiliation: Laboratório de Fungos Dimórficos Patogênicos, Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Diego Conrado Pereira
authors.initials: DCP
authors.lastname: Rossi
authors.affiliation: Laboratório de Quimioterapia Antifúngica, Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900, ICB II, Lab 150, São Paulo, SP, Brazil.
authors.forename: Cristina de Castro
authors.initials: CC
authors.lastname: Spadari
authors.affiliation: Departments of Medicine and Microbiology & Immunology, Albert Einstein College of Medicine, New York, NY, USA.
authors.forename: Joshua Daniel
authors.initials: JD
authors.lastname: Nosanchuk
authors.affiliation: Laboratório de Fungos Dimórficos Patogênicos, Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Carlos Pelleschi
authors.initials: CP
authors.lastname: Taborda
authors.affiliation: Laboratório de Quimioterapia Antifúngica, Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900, ICB II, Lab 150, São Paulo, SP, Brazil. Electronic address: ishidakelly@usp.br.
authors.forename: Kelly
authors.initials: K
authors.lastname: Ishida
mesh_terms: D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000648:ultrastructure; D004285:Dogs; D004357:Drug Synergism; D006801:Humans; D008543:Melanins / Q000096:biosynthesis*; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D015388:Organelles / Q000187:drug effects / Q000648:ultrastructure; D010228:Paracoccidioides / Q000187:drug effects* / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000494:pharmacology
chemical_list: D000935:Antifungal Agents; D008543:Melanins; D010767:Phosphorylcholine; C039128:miltefosine
keywords: Antifungal; Melanin; Miltefosine; Paracoccidioides