Synergistic interactions between β-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, β-lapachone inhibited Pdr5p, a transporter homologous to those found in Candida albicans.

Aims

To determine whether β-lapachone reverses the resistance phenotype mediated by efflux transporters in C. albicans clinical isolates.

Methods

The antifungal activity of β-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

β-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

β-lapachone is a promising drug candidate to be used as an adjuvant in the treatment of candidiasis caused by fluconazole-resistant C. albicans strains.