Wenqiang Chang1, Ming Zhang1, Ying Li1, Xiaobin Li1, Yanhui Gao1, Zhiyu Xie1, Hongxiang Lou2. 1. 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. 2. 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. Electronic address: louhongxiang@sdu.edu.cn.
Abstract
BACKGROUND: This study is to characterize the antifungal effects of pyridoxatin (PYR), a small natural product isolated from an endolichenic fungus. METHODS: 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). RESULTS: 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. CONCLUSIONS: PYR interferes with the ergosterol synthesis to exert antifungal action. GENERAL SIGNIFICANCE: The elucidated mechanism provides possible applications of PYR in fighting clinical relevant fungal infections.
BACKGROUND: This study is to characterize the antifungal effects of pyridoxatin (PYR), a small natural product isolated from an endolichenic fungus. METHODS: 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). RESULTS: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. CONCLUSIONS:PYR interferes with the ergosterol synthesis to exert antifungal action. GENERAL SIGNIFICANCE: The elucidated mechanism provides possible applications of PYR in fighting clinical relevant fungal infections.
Authors: Bethlehem Kebede; Stephen K Wrigley; Anjali Prashar; Janina Rahlff; Markus Wolf; Jeanette Reinshagen; Philip Gribbon; Johannes F Imhoff; Johanna Silber; Antje Labes; Bernhard Ellinger Journal: Mar Drugs Date: 2017-03-23 Impact factor: 5.118