Resumo

Introduction: Yeasts, mainly Candida spp, are considered the main causative agents of opportunistic mycoses. Despite the potent antifungal agents available, high mortality rates associated with candidiasis are often noticed, especially in immunocompromised and immunosuppressed patients on account of HIV injection, chemotherapy, organ transplants and surgical procedures. Moreover, the uncontrolled use of antifungals has been worsening the situation and new cases of resistance are reported increasingly. For this reason, there is a growing interest in the search for new antifungal drugs more selective and less toxic, including antifungal combination with natural products. Objective: This study aimed at investigating the antifungal activity of polyphenol’s fraction (PP1) of U. tomentosa alone and combined with Fluconazole and Terbinafine on a strain of Candida krusei (CK01). Materials and Methods: A crude extract from its bark as well an enriched polyphenol fraction from it (PP1) were prepared for that intend specifically. The Minimum Inhibitory Concentration (MIC) and the Fractional Inhibitory Concentration Index (FIC) were assayed using both products separately as well as PP1 combined with commercials antifungals. The FIC value was obtained by the checkerboard technique. Results and Discussion: When assayed separately, PP1 and Fluconazole showed MICs of 30 µg/mL and 64 µg/mL, respectively. Noteworthy, both MIC values were decreased substantially after combining PP1 and Fluconazole, namely, to 7.5 µg/mL and 16 µg/mLf of PP1 and FLU, respectively. A similar effect against the same strain, but more intense, was observed when PP1 and terbinafine were combined. In that occasion, the respective MIC values dropped from 15 µg/mL and 64 µg/mL to 7.5 µg/mL and 4 µg/mL, respectively. Additionally, the FIC values were 0,5 and 0,562, respectively. The results indicate a possible synergistic effect of the association of PP1 with Fluconazole to inhibit growth of C. krusei strain and additive for PP1 and Terbinafine. Conclusion: Synergic and additive antifungal effects on strain of C. krusei were observed after associating a polyphenol fraction of U. tomentosa and commercials antifungals. This finding suggests the potential use of such combinations as a new therapeutic approach against resistant fungal strains.