Abstract：
The development of new effective antifungal agents is essential to combat fungal infections. Tetrahydrocarbazole has been exploited as a promising skeleton against various pathogenic microorganisms and is used to search for novel active antifungal compounds. In this study, a library composed of small tetrahydrocarbazole compounds was screened, and a potent antifungal agent, CAR-8, was identified with a minimum inhibitory concentration of 2-4 μg/mL against Candida albicans. CAR-8 showed strong fungicidal activities and killed almost all C. albicans within 3 h at a concentration of 16 μg/mL. At concentrations of 2 and 8 μg/mL, CAR-8 significantly inhibited the formation of hyphae and biofilms. Moreover, CAR-8 at 10 and 20 mg/kg reduced the fungal load and improved the survival in the C. albicans infection model in the invertebrate Galleria mellonella. Transcriptome analysis revealed significant changes in the expression of genes associated with protein processing in the endoplasmic reticulum (ER), ER-associated degradation, and unfolded protein response (UPR), which suggested that CAR-8 treatment induced ER stress. Moreover, CAR-8 treatment resulted in various phenotypes similar to tunicamycin, a classical ER stress inducer. These included nonconventional splicing of HAC1 mRNA, the fragmented morphology of ER, the distribution changes of GFP-Snc1 in Saccharomyces cerevisiae, and cell apoptosis probably caused by ER stress. More importantly, the disruption of IRE1 or HAC1 increased the sensitivity of C. albicans to CAR-8, confirming that the UPR signaling pathway was critical for CAR-8 resistance. Overall, our study identifies a potent ER stress-induced antifungal compound that will help the discovery of new antifungal drugs.
摘要：
开发新的有效抗真菌药物对于对抗真菌感染至关重要。四烃唑已被用作对抗各种病原微生物的有前途的骨架，并用于寻找新型活性抗真菌化合物。在这项研究中,筛选了由小四氢咔唑化合物组成的文库，和一种有效的抗真菌剂,CAR-8被鉴定为对白色念珠菌的最小抑制浓度为2-4μg/mL。CAR-8显示出强大的杀真菌活性，并在3小时内以16μg/mL的浓度杀死几乎所有的白色念珠菌。浓度为2和8μg/mL时，CAR-8显著抑制菌丝和生物膜的形成。此外，10和20mg/kg的CAR-8减少了无脊椎动物Galleriamellonella的白色念珠菌感染模型中的真菌负荷并提高了存活率。转录组分析显示，内质网（ER）中与蛋白质加工相关的基因表达发生了显着变化，ER相关降解，和未折叠的蛋白质反应（UPR），这表明CAR-8治疗诱导内质网应激。此外，CAR-8治疗导致与衣霉素相似的各种表型，经典的ER应力诱导剂。这些包括HAC1mRNA的非常规剪接，ER的碎片形态，GFP-Snc1在酿酒酵母中的分布变化,细胞凋亡可能是由内质网应激引起的。更重要的是,IRE1或HAC1的破坏增加了白色念珠菌对CAR-8的敏感性,证实UPR信号通路对于CAR-8耐药至关重要.总的来说,我们的研究确定了一种有效的ER应激诱导的抗真菌化合物，这将有助于发现新的抗真菌药物。
