Inhibitory effect of menthol on expression of aspartyl proteinase 1 in fluconazole-resistant Candida albicans

Abstract

Introduction: Fluconazole-resistant Candida albicans is one of the biggest problems seen in clinical practices. One of the most common ways to resolve this problem is the use of natural pure compounds such as menthol. The aims of this study were to investigate the hyphal formation and gene expression profiling of fluconazole-resistant C. albicans treated by menthol. Methods: Colonization of vaginal isolates of C. albicans was recognized and fluconazole-resistant yeasts detected by WHONET software. The relative minimum inhibitory concentrations (MICs) of menthol were determined by broth microdilution for fluconazole-resistant isolates. The potency of menthol to inhibit hyphal formation was exploited using a light microscope. A quantitative real-time RT- PCR was used to measure the expression of SAP1 . Results: Almost 100% of colonized vaginal isolates of C. albicans was found to be fluconazole-resistant. MIC90 for menthol in fluconazole-resistant isolates was 1.6 to 25 μg/mL. Furthemore, all isolates treated with menthol showed a significant reduction in hyphae and number of planktonic cells. In the fluconazole-resistance C. albicans cells treated with fluconazole, the expression levels of SAP1 increased by 1.53- (2×MIC conc.) and 1.43-fold (1×MIC conc.). However, treatment with menthol down regulated the SAP1 expression by 2.02- and 1.85-fold at concentrations of 2 × MIC and 1 × MIC, respectively (P ≤ 0.05). Conclusion: This study suggests that menthol might have potential applications in treatment of infections, due to fluconazole-resistance C. albicans. In addition, SAP1 could be probable molecular target of menthol in C. albicans.