Abstract
The primary objective of this work was to evaluate the capability of curcumin, a natural compound found in the Curcuma longa plant, to sensitize a clinical isolate of Candida albicans, which was found to have a high resistance to fluconazole. In addition, we assessed whether the resistance of this isolate was the result of the existence of efflux pumps, which could confer a multiple drug resistance phenotype. To evaluate azole resistance, we used the Clinical Laboratory Standard Institute (CLSI) MIC assays procedures with minor modifications. For evaluation of synergistic interaction of curcumin and fluconazole, checkerboard experiments were employed. Nile red and Rhodamine 6G accumulation assays were used to evaluate efflux pump activity. Curcumin was found to have a great capability to inhibit fluconazole resistance of the isolate of C. albicans. It was capable of restoring its sensitivity to this azole when used at 11 μM. Analysis with different azoles and the two indicated dyes showed that an efflux pump could be acting and contributing to the resistance of this isolate to fluconazole. The results suggest that a major facilitator superfamily (MFS) transporter might be involved in this process.
Acknowledgements
The authors would like to thank Dr Nikhat Manzoor (Central University, India) and Dr Erwin Lamping (Otago University, New Zealand) for critical review of this manuscript, and also Dr Rodrigo Bisaggio (IFRJ, Brazil) for help with the fluorescence experiments.
The research outlined in this paper was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq - Proc. 472548/2008-5), Fundação de Amparo a Pesquisa do Estado do Rio de Janeiro (FAPERJ) and by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES-Procad), Brazil.
No ethical approval was required.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the manuscript.
This paper was first published online on Early Online on 9 May 2011.