Screening of Indonesian National Formulary Drugs as Potential Efflux Pump Inhibitors Of Candida albicans

Enrico Bramantyo Adi Nugroho, apt. Setyowati Triastuti Utami, M.Sc., Ph.D. ; Gusnaniar, M. Biotech., Ph. D.

2026 | Skripsi | FARMASI

Fluconazole (FLC) resistance in Candida albicans has become an increasing clinical concern. One of the major mechanisms underlying this resistance is the overexpression of efflux transporters, including Cdr1, Cdr2, and Mdr1, which reduce intracellular antifungal drug accumulation. This study aimed to evaluate the antifungal activity of selected antibacterial drugs listed in the Indonesian National Formulary and to investigate their interactions with fungal efflux transporters using recombinant Saccharomyces cerevisiae strains overexpressing fungal efflux pumps from C. albicans. This study was conducted in vitro using S. cerevisiae ADD, ADD/CaCDR1A, ADD/CaCDR2A, ADD/CaMDR1A, ADD/CgCDR1, ADD/CgPDH1, ADD/HsABCB1, C. albicans ATCC 10231, and the clinical isolate C. albicans UR-RSA-23. Antifungal activity was evaluated using disk diffusion and liquid microdilution assays to determine MIC90 values. The potential inhibition of fungal efflux transporters was assessed using an FLC chemosensitization assay performed in the presence of strain-specific 0.25×MIC FLC concentrations. Among all antibiotics tested in the disk diffusion assay, only gentamicin (GM) and amikacin (AMK) exhibited detectable antifungal activity against all recombinant S. cerevisiae strains, whereas the remaining antibiotics showed no detectable antifungal activity. Neither GM nor AMK produced inhibition zones against C. albicans ATCC 10231 or UR-RSA-23. However, both compounds demonstrated weak antifungal bioactivity, as reflected by their high MIC?? values. Compared with FLC, GM and AMK showed no substantial increase in MIC90 values of efflux transporter-overexpressing strains compared with the ADD parental strain, suggesting that the antifungal activities of GM and AMK were not significantly influenced by the fungal efflux transporters. Chemosensitization assays with GM and AMK demonstrated only a slight enhancement of growth inhibition in the presence of FLC, indicating an additive or weak synergistic interaction and no strong evidence of direct efflux pump inhibition. Overall, GM and AMK displayed limited antifungal potential and are unlikely to function as fungal efflux pump inhibitors.

Fluconazole (FLC) resistance in Candida albicans has become an increasing clinical concern. One of the major mechanisms underlying this resistance is the overexpression of efflux transporters, including Cdr1, Cdr2, and Mdr1, which reduce intracellular antifungal drug accumulation. This study aimed to evaluate the antifungal activity of selected antibacterial drugs listed in the Indonesian National Formulary and to investigate their interactions with fungal efflux transporters using recombinant Saccharomyces cerevisiae strains overexpressing fungal efflux pumps from C. albicans. This study was conducted in vitro using S. cerevisiae ADD, ADD/CaCDR1A, ADD/CaCDR2A, ADD/CaMDR1A, ADD/CgCDR1, ADD/CgPDH1, ADD/HsABCB1, C. albicans ATCC 10231, and the clinical isolate C. albicans UR-RSA-23. Antifungal activity was evaluated using disk diffusion and liquid microdilution assays to determine MIC90 values. The potential inhibition of fungal efflux transporters was assessed using an FLC chemosensitization assay performed in the presence of strain-specific 0.25×MIC FLC concentrations. Among all antibiotics tested in the disk diffusion assay, only gentamicin (GM) and amikacin (AMK) exhibited detectable antifungal activity against all recombinant S. cerevisiae strains, whereas the remaining antibiotics showed no detectable antifungal activity. Neither GM nor AMK produced inhibition zones against C. albicans ATCC 10231 or UR-RSA-23. However, both compounds demonstrated weak antifungal bioactivity, as reflected by their high MIC90 values. Compared with FLC, GM and AMK showed no substantial increase in MIC90 values of efflux transporter-overexpressing strains compared with the ADD parental strain, suggesting that the antifungal activities of GM and AMK were not significantly influenced by the fungal efflux transporters. Chemosensitization assays with GM and AMK demonstrated only a slight enhancement of growth inhibition in the presence of FLC, indicating an additive or weak synergistic interaction and no strong evidence of direct efflux pump inhibition. Overall, GM and AMK displayed limited antifungal potential and are unlikely to function as fungal efflux pump inhibitors.

Kata Kunci : Indonesia National Formulary Antibiotic Drugs, ABC and MFS transporter, Saccharomyces cerevisiae, Candida albicans, Fluconazole