Babeș-Bolyai University, Faculty of Chemistry and Chemical Engineering, 11 Arany Janos Street, 400028, Cluj-Napoca, Romania.
Babeș-Bolyai University, Faculty of Biology and Geology, 42 Republicii Street, 400015, Cluj-Napoca, Romania.
Sci Rep. 2017 Sep 11;7(1):11125. doi: 10.1038/s41598-017-11600-7.
Rhodotorula mucilaginosa was isolated from a patient with onychomycosis, and identification was confirmed by morphological and cultural characteristics as well as by DNA molecular analysis. Antifungal agents naftifine (10 mg/mL, active substance in Exoderil) and bifonazole (10 mg/mL, active substance in Canespor) were tested in different concentrations to assess in vitro effects on fungal growth and carotenoid synthesis. The antifungal mechanisms of action of naftifine and bifonazole against R. mucilaginosa isolates were similar and affected the biosynthetic pathway of ergosterol. For the first time, this research demonstrates that naftifine affects the carotenoid biosynthetic pathway, producing depigmentation of R. mucilaginosa in solid and liquid media. Furthermore, depigmentation was a reversible process; naftifine-treated yeast cells that were depigmented resumed carotenoid production upon transfer to fresh media. Raman and UV-vis spectrophotometry in conjunction with chromatographic analysis detected changes in carotenoids in yeast cells, with torulene decreasing and B-carotene increasing after repigmentation. Transmission electron micrographs revealed critical ultrastructural modifications in the depigmented cells after naftifine treatment, i.e., a low-electron-density cell wall without visible mucilage or lamellate structure.
粘红酵母从甲真菌病患者中分离得到，通过形态学和培养特征以及 DNA 分子分析确认鉴定。在不同浓度下测试了萘替芬（10mg/mL，Exoderil 中的有效物质）和联苯苄唑（10mg/mL，Canespor 中的有效物质）两种抗真菌药物，以评估其对真菌生长和类胡萝卜素合成的体外影响。萘替芬和联苯苄唑对粘红酵母分离株的抗真菌作用机制相似，均影响麦角固醇的生物合成途径。本研究首次证明，萘替芬影响类胡萝卜素的生物合成途径，导致粘红酵母在固体和液体培养基中出现退色现象。此外，退色是一个可逆的过程；在转移到新鲜培养基后，萘替芬处理的退色酵母细胞恢复类胡萝卜素的产生。拉曼和紫外-可见分光光度法结合色谱分析检测到酵母细胞中类胡萝卜素的变化，经重染后 torulene 减少，β-胡萝卜素增加。透射电子显微镜显示，萘替芬处理后退色细胞发生了关键的超微结构改变，即细胞壁电子密度低，无可见黏液或层状结构。
