Synergistic interactions between ß-lapachone and fluconazole in the inhibition of CaCdr2p and CaMdr1p in Candida albicans.

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.

Synergistic interactions between Beta-lapachone and fluconazole in the inhibition of CaCdr2p and CaMdr1p in Candida albicans / Las interacciones sinérgicas entre la beta-lapachona y el fluconazol en la inhibición de CaCdr2p y CaMdr1p en Candida albicans

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, Beta-lapachone inhibited Pdr5p, a transporter homologous to those found in Candida albicans. AIMS: To determine whether Beta-lapachone reverses the resistance phenotype mediated by efflux transporters in C. albicans clinical isolates. METHODS: The antifungal activity of Beta-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: Beta-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: Beta-lapachone is a promising drug candidate to be used as an adjuvant in the treatment of candidiasis caused by fluconazole-resistant C. albicans strains

ANTECEDENTES: Las tasas de mortalidad de infecciones invasivas causadas por Candida están en aumento, principalmente entre los pacientes inmunocomprometidos. Estas infecciones son difíciles de tratar debido a la creciente incidencia de resistencia a los antifúngicos. La sobreexpresión de los transportadores dependientes de ATP y los de la superfamilia de facilitadores principales es el mayor responsable del fracaso de las terapias antimicóticas. En un modelo de Saccharomyces cerevisiae, la beta-lapachona inhibió Pdr5p, un transportador homólogo a los encontrados en Candida albicans. OBJETIVOS: Determinar si la beta-lapachona revierte el fenotipo de resistencia mediado por transportadores de eflujo en aislamientos clínicos de C. albicans. MÉTODOS: Se midió la actividad antifúngica de la beta-lapachona combinada con fluconazol mediante ensayos de quimiosensibilización con agarosa y microdilución. Las actividades CaCdr2p y CaMdr1p se evaluaron mediante la acumulación de colorantes fluorescentes, y la actividad de ATPasa se evaluó usando membranas plasmáticas enriquecidas con transportador. RESULTADOS: La beta-lapachona revirtió la resistencia antifúngica de las cepas de S. cerevisiae y C. albicans que sobreexpresaban los transportadores CaCdr2p y CaMdr1p al inhibir sus actividades. El compuesto no afectó la actividad ATPasa de CaCdr2p. CONCLUSIONES: La beta-lapachona es una candidata prometedora para ser utilizada como adyuvante en el tratamiento de la candidiasis causada por cepas de C. albicans resistentes al fluconazol

Antiproliferative and ultrastructural effects of phenethylamine derivatives on promastigotes and amastigotes of Leishmania (Leishmania) infantum chagasi.

Leishmania (Leishmania) infantum chagasi is one of the agents that cause visceral leishmaniasis. This disease occurs more frequently in third world countries, such as Brazil. The treatment is arduous, and is dependent on just a few drugs like the antimonial derivatives and amphotericin B. Moreover, these drugs are not only expensive, but they can also cause severe side effects and require long-term treatment. Therefore, it is very important to find new compounds that are effective against leishmaniasis. In the present work we evaluated a new group of synthetic amides against the promastigote and amastigote forms of L. infantum chagasi. The results showed that one of these amides in particular, presented very effective activity against the promastigotes and amastigotes of L. infantum chagasi at low concentrations and it also presented low toxicity for mammal cells, which makes this synthetic amide a promising drug for combating leishmaniasis.

Synthetic organotelluride compounds induce the reversal of Pdr5p mediated fluconazole resistance in Saccharomyces cerevisiae.

BACKGROUND: Resistance to fluconazole, a commonly used azole antifungal, is a challenge for the treatment of fungal infections. Resistance can be mediated by overexpression of ABC transporters, which promote drug efflux that requires ATP hydrolysis. The Pdr5p ABC transporter of Saccharomyces cerevisiae is a well-known model used to study this mechanism of antifungal resistance. The present study investigated the effects of 13 synthetic compounds on Pdr5p. RESULTS: Among the tested compounds, four contained a tellurium-butane group and shared structural similarities that were absent in the other tested compounds: a lateral hydrocarbon chain and an amide group. These four compounds were capable of inhibiting Pdr5p ATPase activity by more than 90%, they demonstrated IC50 values less than 2 µM and had an uncompetitive pattern of Pdr5p ATPase activity inhibition. These organotellurides did not demonstrate cytotoxicity against human erythrocytes or S. cerevisiae mutant strains (a strain that overexpress Pdr5p and a null mutant strain) even in concentrations above 100 µM. When tested at 100 µM, they could reverse the fluconazole resistance expressed by both the S. cerevisiae mutant strain that overexpress Pdr5p and a clinical isolate of Candida albicans. CONCLUSIONS: We have identified four organotellurides that are promising candidates for the reversal of drug resistance mediated by drug efflux pumps. These molecules will act as scaffolds for the development of more efficient and effective efflux pump inhibitors that can be used in combination therapy with available antifungals.