Chang Wenqiang, Zhang Ming, Li Ying, Li Xiaobin, Gao Yanhui, Xie Zhiyu, Lou Hongxiang
Department of Natural Product Chemistry, Key Lab of Chemical Biology of Ministry of Education, Shandong University, No. 44 West Wenhua Road, Jinan City, Shandong Province, China.
Department of Natural Product Chemistry, Key Lab of Chemical Biology of Ministry of Education, Shandong University, No. 44 West Wenhua Road, Jinan City, Shandong Province, China.
Biochim Biophys Acta. 2015 Sep;1850(9):1762-71. doi: 10.1016/j.bbagen.2015.05.005. Epub 2015 May 8.
This study is to characterize the antifungal effects of pyridoxatin (PYR), a small natural product isolated from an endolichenic fungus.
The susceptibility tests in vitro and in vivo by using Caenorhabditis elegans as an infectious model were performed to evaluate the antifungal efficacy of PYR against Candida species. The cytotoxicity of PYR against normal human cells was tested using MTT assay. The transcriptional levels of genes related to sterol synthesis and cell cycle regulation were measured using real-time quantitative PCR (qPCR). The contents ergosterol, squalene, lanosterol were detected by liquid chromatography/tandem mass spectrometry (LC/MS).
PYR was effective against four tested Candida species with its minimal inhibitory concentrations (MICs) ranging from 1-4μg/ml. No obvious cytotoxicity was observed for PYR against normal human cells. PYR inhibited the growth of Candida albicans, preventing the biofilm formation. And the antifungal action was independent on efflux pumps. The in vivo test showed PYR greatly prolonged the survival of infected C. elegans. qPCR results revealed that most of the genes related to sterol biosynthesis were considerably down-regulated in PYR-treated cells. Determination of the sterol content found that PYR inhibited the ergosterol synthesis dose dependently and caused the accumulation of squalene and lanosterol. Moreover, analysis of the structure-activity relationship revealed the heterocyclic hydroxamic acid in PYR was the key group for the antifungal action.
PYR interferes with the ergosterol synthesis to exert antifungal action.
The elucidated mechanism provides possible applications of PYR in fighting clinical relevant fungal infections.
本研究旨在表征从内生地衣真菌中分离出的一种天然小分子产物吡哆他汀（PYR）的抗真菌作用。
以秀丽隐杆线虫作为感染模型进行体外和体内药敏试验，以评估PYR对念珠菌属的抗真菌疗效。采用MTT法检测PYR对正常人细胞的细胞毒性。使用实时定量PCR（qPCR）测量与甾醇合成和细胞周期调控相关基因的转录水平。通过液相色谱/串联质谱（LC/MS）检测麦角甾醇、角鲨烯、羊毛甾醇的含量。
PYR对四种受试念珠菌有效，其最低抑菌浓度（MIC）范围为1-4μg/ml。未观察到PYR对正常人细胞有明显的细胞毒性。PYR抑制白色念珠菌的生长，阻止生物膜形成。并且抗真菌作用不依赖于外排泵。体内试验表明PYR大大延长了感染秀丽隐杆线虫的存活时间。qPCR结果显示，在经PYR处理的细胞中，大多数与甾醇生物合成相关的基因显著下调。甾醇含量测定发现，PYR剂量依赖性地抑制麦角甾醇合成，并导致角鲨烯和羊毛甾醇的积累。此外，构效关系分析表明，PYR中的杂环异羟肟酸是抗真菌作用的关键基团。
PYR通过干扰麦角甾醇合成发挥抗真菌作用。
阐明的机制为PYR在对抗临床相关真菌感染中的应用提供了可能。
