RESUMO
Candida albicans is an opportunistic human pathogen with the ability to differentiate and grow in filamentous forms and exist as biofilms. The biofilms are a barrier to treatment as they are often resistant to the antifungal drugs. In this study, we investigated the antifungal activity of allicin, an active compound of garlic on various isolates of C. albicans. The effect of allicin on biofilm production in C. albicans as compared to fluconazole, an antifungal drug, was investigated using the tetrazolium (XTT) reduction-dependent growth and crystal violet assays as well as scanning electron microscopy (SEM). Allicin-treated cells exhibited significant reduction in biofilm growth (p<0.05) compared to fluconazole-treated and also growth control cells. Moreover, observation by SEM of allicin and fluconazole-treated cells confirmed a dose-dependent membrane disruption and decreased production of organisms. Finally, the expression of selected genes involved in biofilm formation such as HWP1 was evaluated by semi-quantitative RT-PCR and relative real time RT-PCR. Allicin was shown to down-regulate the expression of HWP1.
Assuntos
Antifúngicos/farmacologia , Biofilmes/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Candida albicans/fisiologia , Fluconazol/farmacologia , Proteínas Fúngicas/biossíntese , Glicoproteínas de Membrana/biossíntese , Ácidos Sulfínicos/farmacologia , Candida albicans/genética , Candida albicans/metabolismo , Dissulfetos , Proteínas Fúngicas/antagonistas & inibidores , Proteínas Fúngicas/genética , Alho/química , Regulação Fúngica da Expressão Gênica/efeitos dos fármacos , Glicoproteínas de Membrana/antagonistas & inibidores , Glicoproteínas de Membrana/genética , Reação em Cadeia da Polimerase em Tempo RealRESUMO
The efficacy of allicin compared with fluconazole in alleviating systemic Candida albicans infections was evaluated both in vitro and in vivo through a systemic candidiasis mouse model. Determination of in vitro minimum inhibitory concentrations (MICs) for different C. albicans isolates revealed that both allicin and fluconazole showed different MICs that ranged from 0.05 to 12.5 µg mL(-1) and 0.25 to 16 µg mL(-1) , respectively. A time-kill study showed a significant effect of allicin (P<0.01) against C. albicans, comparable to that of fluconazole. Scanning electron microscopy observation revealed that, similar to fluconazole, allicin produced structural destruction of C. albicans cell surface at low MIC and lysis or puncture at high MIC concentrations. Treatment of BALB/c mice systemically infected with C. albicans showed that although the allicin treatment (at 5 mg kg(-1) day(-1) ) was slightly less efficacious than fluconazole treatment in terms of the fungal load reduction and host survival time, it was still effective against C. albicans in terms of mean survival time, which increased from 8.4 to 15.8 days. These results demonstrate the efficacy of anticandidal effects of allicin both in vitro and in an animal model of candidiasis and affirm the potential of allicin as an adjuvant therapy to fluconazole.