L Wang1, J Shen1, L Xu1,2, J Gao1, C Zhang3, Y Wang4, F Chen5. 1. Department of Pharmaceutical Science, School of Medicine, Hangzhou Normal University, Hangzhou, China. 2. Ningbo Women and Children's Hospital, Ningbo, China. 3. State Key Laboratory of Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou, China. 4. Zhejiang Chinese Medical University, Hangzhou, China. 5. School of Basic Medical Sciences & Forensic Medicine, Hangzhou Medical College, Hangzhou, China.
Abstract
AIM: To investigate the bioactive metabolite of endophytic fungus from Kalimeris indica. METHODS AND RESULTS: A strain ZJLQ336 was separated from the leaves of K. indica. It was identified as Cadophora orchidicola based on the phylogenetic analysis of ITS-rDNA sequences. From the fermentation broth a metabolite cercosporamide (compound 1) was isolated, and its structure was determined by spectroscopic analysis. Additionally, this compound was subjected to bioactivity assays, including antifungal activity against seven plant pathogenic fungi, as well as its potential immunoregulatory effects on HEK-BLUE™-hTLR4 cells, splenocytes and macrophages. The results showed that cercosporamide had strong growth inhibition against five common plant pathogenic fungi, including Pestalotia diospyri, Botrytis cinerea, Fusarium oxysporum, Sclerotium rolfsii and Penicillum digitatum with EC50 values of 5·29 × 10-3 , 0·61, 0·93, 2·89 and 6·7 μg ml-1 respectively. Among which S. rolfsii was one of the main pathogens in K. indica. Moreover, cercosporamide not only significantly stimulated TLR4 activation, splenocyte proliferation and production of cytokines, IFN-γ and TNF-α, but also up-regulated the production of TNF-α and NO in RAW264.7 macrophages clearly. CONCLUSIONS: This is the first report of endophytic C. orchidicola from K. indica and its metabolite cercosporamide. The results of pharmacological tests highlight the potential fungicide and TLR4 agonist of cercosporamide. SIGNIFICANCE AND IMPACT OF THE STUDY: This study indicates endophytic fungi are good resources for natural bioactive metabolites. It also suggests that cercosporamide is a potential fungicide and TLR4 agonist.
AIM: To investigate the bioactive metabolite of endophytic fungus from Kalimeris indica. METHODS AND RESULTS: A strain ZJLQ336 was separated from the leaves of K. indica. It was identified as Cadophora orchidicola based on the phylogenetic analysis of ITS-rDNA sequences. From the fermentation broth a metabolite cercosporamide (compound 1) was isolated, and its structure was determined by spectroscopic analysis. Additionally, this compound was subjected to bioactivity assays, including antifungal activity against seven plant pathogenic fungi, as well as its potential immunoregulatory effects on HEK-BLUE™-hTLR4 cells, splenocytes and macrophages. The results showed that cercosporamide had strong growth inhibition against five common plant pathogenic fungi, including Pestalotia diospyri, Botrytis cinerea, Fusarium oxysporum, Sclerotium rolfsii and Penicillum digitatum with EC50 values of 5·29 × 10-3 , 0·61, 0·93, 2·89 and 6·7 μg ml-1 respectively. Among which S. rolfsii was one of the main pathogens in K. indica. Moreover, cercosporamide not only significantly stimulated TLR4 activation, splenocyte proliferation and production of cytokines, IFN-γ and TNF-α, but also up-regulated the production of TNF-α and NO in RAW264.7 macrophages clearly. CONCLUSIONS: This is the first report of endophytic C. orchidicola from K. indica and its metabolite cercosporamide. The results of pharmacological tests highlight the potential fungicide and TLR4 agonist of cercosporamide. SIGNIFICANCE AND IMPACT OF THE STUDY: This study indicates endophytic fungi are good resources for natural bioactive metabolites. It also suggests that cercosporamide is a potential fungicide and TLR4 agonist.