RESUMO

Candida spp. can be found in the human microbiome. However, immunocompromised patients are likely to develop invasive Candida infections, with mortality rates higher than 50%. The discovery of C. auris, a species that rapidly acquire antifungal resistance, increased the concern about Candida infections. The limited number of antifungal agents and the high incidence of resistance to them make imperative the development of new antifungal drugs. ß-lapachone is a biological active naphthoquinone that displays antifungal activity against C. albicans and C. glabrata. The aim of this study was to evaluate if this substance affects C. auris growth and elucidate its mechanism of action. A fluconazole-resistant C. auris isolate was used in this study. The antifungal activity of ß-lapachone was determined through microbroth dilution assays, and its mechanism of action was evaluated using fluorescent probes. Interaction with fluconazole and amphotericin B was assessed by disk diffusion assay and checkerboard. ß-lapachone inhibited planktonic C. auris cell growth by 92.7%, biofilm formation by 84.9%, and decrease the metabolism of preformed biofilms by 87.1% at 100 µg/ml. At 100 µg/ml, reductions of 30% and 59% of Calcofluor White and Nile red fluorescences were observed, indicating that ß-lapachone affects cell wall chitin and neutral lipids content, respectively. Also, the ratio 590 nm/529 nm of JC-1 decreased 52%, showing that the compound affects mitochondria. No synergism was observed between ß-lapachone and fluconazole or amphotericin B. Data show that ß-lapachone may be a promising candidate to be used as monotherapy to treat C. auris resistant infections.

Assuntos

RESUMO

BACKGROUND: Mortality rate of invasive Candida infections is raising mainly amongst immunocompromised patients. These infections are hard-to-treat mainly due to the increasing incidence of resistance. The overexpression of ATP-binding cassette and major facilitator superfamily transporters is the main responsible for the failure of antifungal therapies. In a Saccharomyces cerevisiae model, ß-lapachone inhibited Pdr5p, a transporter homologous to those found in Candida albicans. AIMS: To determine whether ß-lapachone reverses the resistance phenotype mediated by efflux transporters in C. albicans clinical isolates. METHODS: The antifungal activity of ß-lapachone combined with fluconazole was measured by agarose chemosensitization and microdilution assays. CaCdr2p and CaMdr1p activities were evaluated through fluorescent dyes accumulation. ATPase activity was assessed using transporter-enriched plasma membranes. RESULTS: ß-lapachone reverted antifungal resistance of S. cerevisiae and C. albicans strains overexpressing CaCdr2p and CaMdr1p transporters by inhibiting these proteins activities. CaCdr2p ATPase activity was not impaired by the compound. CONCLUSIONS: ß-lapachone is a promising drug candidate to be used as an adjuvant in the treatment of candidiasis caused by fluconazole-resistant C. albicans strains.

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RESUMO

Anthelmintics used for intestinal helminthiasis treatment are generally effective; however, their effectiveness in tissue parasitosis (i.e. visceral toxocariasis) is moderate. The aim of this study was to evaluate the in vitro activity of lapachol, ß-lapachone and phenazines in relation to the viability of Toxocara canis larvae. A concentration of 2 mg/mL (in duplicate) of the compounds was tested using microculture plates containing Toxocara canis larvae in an RPMI-1640 environment, incubated at 37 °C in 5% CO2 tension for 48 hours. In the 2 mg/mL concentration, four phenazines, lapachol and three of its derivatives presented a larvicide/larvistatic activity of 100%. Then, the minimum larvicide/larvistatic concentration (MLC) test was conducted. The compounds that presented the best results were nor-lapachol (MLC, 1 mg/mL), lapachol (MLC 0.5 mg/mL), ß-lapachone, and ß-C-allyl-lawsone (MLC, 0.25 mg/mL). The larvae exposed to the compounds, at best MLC with 100% in vitro activity larvicide, were inoculated into healthy BALB/c mice and were not capable of causing infection, confirming the larvicide potential in vitro of these compounds.

Assuntos

RESUMO

Anthelmintics used for intestinal helminthiasis treatment are generally effective; however, their effectiveness in tissue parasitosis (i.e. visceral toxocariasis) is moderate. The aim of this study was to evaluate the in vitro activity of lapachol, β-lapachone and phenazines in relation to the viability of Toxocara canis larvae. A concentration of 2 mg/mL (in duplicate) of the compounds was tested using microculture plates containing Toxocara canis larvae in an RPMI-1640 environment, incubated at 37 °C in 5% CO2 tension for 48 hours. In the 2 mg/mL concentration, four phenazines, lapachol and three of its derivatives presented a larvicide/larvistatic activity of 100%. Then, the minimum larvicide/larvistatic concentration (MLC) test was conducted. The compounds that presented the best results were nor-lapachol (MLC, 1 mg/mL), lapachol (MLC 0.5 mg/mL), β-lapachone, and β-C-allyl-lawsone (MLC, 0.25 mg/mL). The larvae exposed to the compounds, at best MLC with 100% in vitro activity larvicide, were inoculated into healthy BALB/c mice and were not capable of causing infection, confirming the larvicide potential in vitro of these compounds.

Os anti-helmínticos empregados no tratamento das helmintoses intestinais, de modo geral, são eficazes, porém nas parasitoses teciduais, como é o caso da toxocaríase visceral, a eficácia é moderada. Este estudo teve como objetivo avaliar in vitro a atividade do lapachol, β-lapachona e fenazinas derivadas da β-lapachona sobre a viabilidade de larvas de Toxocara canis. Os compostos foram testados na concentração de 2 mg/mL (em duplicata) em placas de microcultivo, contendo larvas de T. canis em meio RPMI-1640, sendo incubados, a 37 °C, em tensão de CO2 de 5%, por 48 horas. Na concentração de 2 mg/mL, quatro fenazinas, o lapachol e três derivados, apresentaram atividade larvicida/larvostática de 100%. A seguir, foi realizado o teste de concentração larvicida/larvostártica mínima (CLM). Os compostos que apresentaram os melhores resultados foram o nor-lapachol (CLM, 1 mg/mL), lapachol (CLM, 0,5 mg/mL), a β-lapachona e a β-C-alil-lausona (CLM, 0,25 mg/mL). As larvas expostas aos compostos, na melhor CLM 100% in vitro foram inoculadas em camundongos BALB/c saudáveis não sendo capazes de causar infecção, confirmando o potencial larvicida in vitro desses compostos.

Assuntos