Expression analysis of SIR2 and SAPs1-4 gene expression in Candida albicans treated with allicin compared to fluconazole.

One of the main factors for virulence of fungus such as Candida albicans is the ability to change its morphology from yeast to hyphae. Allicin, one of the volatile sulfur-oil compounds from freshly crushed garlic, has a variety of antifungal activities. In this study, the effect of allicin on growth and hyphae production in C. albicans as compared to fluconazole, an antifungal drug was investigated using survival time in vitro and microscopic image at different time intervals. Additionally, the expression of selected genes involved in hyphae formation and development such as SIR2 and SAP1-4 was evaluated by semi-quantitative RT-PCR and relative real time RT-PCR. Allicin was shown to down-regulate the expression of SIR2 (5.54 fold), similar to fluconazole (3.48 fold) at 2x MIC concentrations. Interestingly, allicin had no effect on SAPs1-4 expression, whereas fluconazole was able to suppress SAP4 expression. Our findings showed that allicin was effective in suppressing hyphae development of C. albicans to an extent that is sometimes equal or more than fluconazole. Moreover, allicin and fluconazole seemed to share a common anti-Candida mechanism through inhibition of SIR2 gene, while fluconazole appeared to also exert its fungistatic effect through another pathway that involved SAP4 suppression.