Resumo

Species from the genus Candida are the main fungal pathogens involved in human infections. Considering the emergency of non-albicans species and the occurrence of intrinsic and acquired resistance of these yeasts, it’s been observed a growing interest in the search for new antifungal agents. The objective of this study was to evaluate the antifungal activity of the flavonoid baicalein against Candida albicans, C. tropicais and C. parapsilosis, by the determination of the Minimal Inhibitory Concentration, as well as to determine the decreasing of the Colony Forming Units (UFC/ml), analyze the influence of these flavonoids in the growth curves and generation times, evaluate the synergistic potential of baicalein with fluconazol and analize the possible morphological and ultra-structural alterations of the baicalein, fluconazol and of the synergic combination of them, through scanning electron microscopy (SEM). The data showed that the baicalein presented IC50 values between 400 and 50 µmol/L, for all three Candida species tested. The analysis of decrease in the number of CFU/ml showed that, in the maximum concentration tested (1000 µmol/L), there was a decrease of 2 log for one of the tested C. albicans. The analysis of the growth curves showed that the baicalein was capable of slowing down the lag phase of the three species, retarding between 6 and 12 hours when compared to the control. Still, the baicalein was capable of increase the generation times of the three tested species. The SEM analysis showed that the treatment with fluconazol kept the cells clustered, without the presence of hyphae, when compared to the controls. The baicalein did not show difference regarding to the presence of hyphae and blastoconidia, but the treatment presented a higher production of extra-cellular material when compared to the controls. In the synergic combination between baicalein and fluconazol, there was a high production of extra-cellular material when compared to the other treatments. In C. tropicalis the presence of fluconazol associated with baicalein was capable of inhibit the differentiation in the filamentous form. The obtained data showed the potential of the baicalein as antifungal agent and its efficiency as an agent of synergism with fluconazol on the strains and isolates of different species of Candida.