地衣内生菌Elaphocordyceps sp.的代谢产物

Metabolites of endolichenic fungus Elaphocordyceps sp.

摘要:

【目的】通过对猫耳衣内生菌Elaphocordyceps sp.代谢产物的研究，以期获得结构新颖、抗菌活性强的化合物。【方法】采用PCR扩增和测定nrDNA的ITS (Internal transcribed spacer)序列，在GenBank数据库中比对，并采用构建系统发育树的方法，确定该菌株的分类地位。采用硅胶柱色谱、凝胶柱色谱和高效液相色谱方法进行成分分离。根据理化性质和波谱数据进行结构鉴定。采用倍比稀释法进行抑菌活性测定。【结果】鉴定出供试菌株为地衣内生菌Elaphocordyceps sp.。从Elaphocordyceps sp.的发酵液中分离得到3个化合物，结构鉴定为麦角甾醇、4,8-Dihydroxy-1-tetralone和De-O-methyldiaporthin。化合物1–3表现弱的抑制白色念珠菌活性。化合物3具有非常强的植物毒活性(叶片敏感度：4 nmol)。化合物3在地衣内生菌Elaphocordyceps sp.发酵液中的得率为0.75 mg/L (3.2′103 nmol)，远远高于其对叶片敏感度4 nmol。【结论】由猫耳衣内生菌Elaphocordyceps sp.产生的De-O-methyldiaporthin可作为一种微生物源除草剂。

Abstract:

[Objective] To aquire compounds with novel structures or potent antimicrobial activities through research on metabolites of endolichenic fungus Elaphocordyceps sp. isolated from Leptogium sp.. [Methods] We confirmed taxonomy status of the endolichenic fungus by PCR amplification, evaluation of the ITS (internal transcribed spacer) sequence of nrDNA, sequence comparision in GenBank Database and construction of the phylogenetic tree. Constitutes were isolated by the gel column chromatography, sephadex LH-20 and HPLC methods. Structures were elucidated by physicochemical properties and spectral data analysis. Double dilution method was adopted to evaluate antifungal activity. [Results] The testing strain was identified as Elaphocordyceps sp.. Three compounds were isolated and purified from the fermentation of the endolichenic fungus. Their structures were elucidated to be ergosterol, 4,8-dihydroxy-1-tetralone and De-O-methyldiaporthin. The three compounds show weak inhibition on Candida albicans sc5314. De-O-methyldiaporthin exhibits very strong phytotoxic activity, with leaf sensitivity concentration of 4 nmol. The concentration of De-O-methyldiaporthin in fermentation broth of Elaphocordyceps sp. reached 0.75 mg/L (3.2′103 nmol), much higher than the leaf sensitivity concentration of 4 nmol. [Conclusion] De-O-methyldiaporthin produced by the fungus of Elaphocordyceps sp. can be a microbial herbicide.