Citral e geraniol: atividade antifúngica sobre leveduras do gênero Candida de importância hospitalar

• Autor(a) principal: Leite, Maria Clerya Alvino
• Data de Publicação: 2015
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFPB
• Texto Completo: https://repositorio.ufpb.br/jspui/handle/tede/7993
• topic: Atividade antifúngica; Antifungal activity; Candida albicans; Citral; Geraniol; Produtos naturais; Candida albicans; Citral; Geraniol; Biological products; CIENCIAS BIOLOGICAS::FARMACOLOGIA

Candidiasis is an opportunistic infection caused by Candida yeasts. In Brazil, the species C. tropicalis is the second most commonly isolated after C. albicans. Conventional fungal infection treatments are unsatisfactory because of the appearance of resistance and security issues and toxicity of commercially available antifungal drugs. Therefore, it has become essential to develop new drugs and alternative therapies for the treatment of candidiasis. In this context, antifungal compounds of natural origin, such as terpenes, have received much attention in recente times to be promising therapeutic tool for treatment fungal infections. Thus, it was investigated the antifungal activity of citral and geraniol monoterpenes on strains of C. albicans and C. tropicalis. The Minimum Inhibitory Concentration (MIC) and the Minimum Fungicidal Concentration (MFC) were determined by the broth microdilution techniques. Also, it was investigated a possible products action on fungal cell wall (0.8 M sorbitol assay), cell membranes (ergosterol complexation), the time-kill curve, (log CFU/mL) and biological activity on the yeast’s micromorphology. Among the monoterpenes, geraniol was the most potent, as showed the lowest MIC value (16 µg/mL). As for citral, the MIC and MFC was 64 µg/mL for 15 of the 16 tested strains. In accordance with the MIC results, two strains of C. albicans (ATCC 76485 and ML-70) and C. tropicalis (ATCC 13803 and ML-118) were selected for further testing. The result of the possible mechanism of action showed no involvement with cell wall (identical CIM medium with and without addition of sorbitol) or binding to ergosterol (identical CIM medium with and without addition of ergosterol). In the morphological interference assay, it was observed that both citral and geraniol inhibited pseudohyphae and chlamydoconidia formation. It was also found that the monoterpenes have concentration-dependent antifungal activity. It follows, therefore, the citral and geraniol monoterpenes showed potential antifungal activity in vitro against the tested strains, denoting are promising antifungal agents with potential applicability in the treatment of infections caused by Candida yeasts, such as those that occur in the hospital. The probable mechanism of action does not involve the cell wall or binding ergosterol.