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

Reis de Sá LF, Toledo FT, de Sousa BA, Gonçalves AC, Tessis AC, Wendler EP, Comasseto JV, Dos Santos AA, Ferreira-Pereira A - BMC Microbiol. (2014)

Bottom Line: The present study investigated the effects of 13 synthetic compounds on Pdr5p.These organotellurides did not demonstrate cytotoxicity against human erythrocytes or S. cerevisiae mutant strains (a strain that overexpress Pdr5p and a mutant strain) even in concentrations above 100 μM.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Instituto de Microbiologia Paulo de Góes, Departamento de Microbiologia Geral, Laboratório de Bioquímica Microbiana, CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro/RJ, Brazil. alcindo@iq.usp.br.

ABSTRACT

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 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.

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Evaluation of the reversion of the fluconazole resistance by the organotellurides. (A) AD124567 strain of S. cerevisiae: Fluconazole (−): yeast cell growth on YPD solid in absence of fluconazole. Fluconazole (+): yeast cell growth on YPD solid medium in presence of fluconazole at 120 μg/mL. Medium containing FK506 10 μM + fluconazole 120 μg/mL was used as positive control. (B) Resistant Candida albicans strain (clinical isolate): Fluconazole (−): yeast cell growth on Sabouraud solid medium in absence of fluconazole. Fluconazole (+): yeast cell growth on Sabouraud solid in presence of fluconazole at 64 μg/mL.
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Figure 6: Evaluation of the reversion of the fluconazole resistance by the organotellurides. (A) AD124567 strain of S. cerevisiae: Fluconazole (−): yeast cell growth on YPD solid in absence of fluconazole. Fluconazole (+): yeast cell growth on YPD solid medium in presence of fluconazole at 120 μg/mL. Medium containing FK506 10 μM + fluconazole 120 μg/mL was used as positive control. (B) Resistant Candida albicans strain (clinical isolate): Fluconazole (−): yeast cell growth on Sabouraud solid medium in absence of fluconazole. Fluconazole (+): yeast cell growth on Sabouraud solid in presence of fluconazole at 64 μg/mL.

Mentions: The spot assay shown in Figure 6A demonstrates that Pdr5p+ strain, which is resistant to fluconazole (MIC = 600 μg/mL), was able to grow on a medium containing fluconazole at 120 μg/mL as well as in presence of compounds at 100 μM. However, an evident reduction in growth was observed when this strain was incubated in presence of fluconazole (120 μg/mL) associated with any of the four organotellurides (100 μM). Thus, it was possible to demonstrate that these synthetic compounds were able to reverse the fluconazole resistance mediated by Pdr5p in a manner similar to the reversion promoted by FK506. A control using the Pdr5p- mutant (fluconazole sensitive strain (AD1234567)) was performed to confirm that the presence of Pdr5p is responsible for the fluconazole resistance of the AD124567 strain.


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

Reis de Sá LF, Toledo FT, de Sousa BA, Gonçalves AC, Tessis AC, Wendler EP, Comasseto JV, Dos Santos AA, Ferreira-Pereira A - BMC Microbiol. (2014)

Evaluation of the reversion of the fluconazole resistance by the organotellurides. (A) AD124567 strain of S. cerevisiae: Fluconazole (−): yeast cell growth on YPD solid in absence of fluconazole. Fluconazole (+): yeast cell growth on YPD solid medium in presence of fluconazole at 120 μg/mL. Medium containing FK506 10 μM + fluconazole 120 μg/mL was used as positive control. (B) Resistant Candida albicans strain (clinical isolate): Fluconazole (−): yeast cell growth on Sabouraud solid medium in absence of fluconazole. Fluconazole (+): yeast cell growth on Sabouraud solid in presence of fluconazole at 64 μg/mL.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4222501&req=5

Figure 6: Evaluation of the reversion of the fluconazole resistance by the organotellurides. (A) AD124567 strain of S. cerevisiae: Fluconazole (−): yeast cell growth on YPD solid in absence of fluconazole. Fluconazole (+): yeast cell growth on YPD solid medium in presence of fluconazole at 120 μg/mL. Medium containing FK506 10 μM + fluconazole 120 μg/mL was used as positive control. (B) Resistant Candida albicans strain (clinical isolate): Fluconazole (−): yeast cell growth on Sabouraud solid medium in absence of fluconazole. Fluconazole (+): yeast cell growth on Sabouraud solid in presence of fluconazole at 64 μg/mL.
Mentions: The spot assay shown in Figure 6A demonstrates that Pdr5p+ strain, which is resistant to fluconazole (MIC = 600 μg/mL), was able to grow on a medium containing fluconazole at 120 μg/mL as well as in presence of compounds at 100 μM. However, an evident reduction in growth was observed when this strain was incubated in presence of fluconazole (120 μg/mL) associated with any of the four organotellurides (100 μM). Thus, it was possible to demonstrate that these synthetic compounds were able to reverse the fluconazole resistance mediated by Pdr5p in a manner similar to the reversion promoted by FK506. A control using the Pdr5p- mutant (fluconazole sensitive strain (AD1234567)) was performed to confirm that the presence of Pdr5p is responsible for the fluconazole resistance of the AD124567 strain.

Bottom Line: The present study investigated the effects of 13 synthetic compounds on Pdr5p.These organotellurides did not demonstrate cytotoxicity against human erythrocytes or S. cerevisiae mutant strains (a strain that overexpress Pdr5p and a mutant strain) even in concentrations above 100 μM.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Instituto de Microbiologia Paulo de Góes, Departamento de Microbiologia Geral, Laboratório de Bioquímica Microbiana, CCS, Universidade Federal do Rio de Janeiro, Rio de Janeiro/RJ, Brazil. alcindo@iq.usp.br.

ABSTRACT

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 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.

Show MeSH
Related in: MedlinePlus