南海珊瑚来源真菌Aspergillus sp.SCSIO 40435的分离鉴定及其次级代谢产物研究

Isolation, identification, and bioactive metabolites of coral-derived fungus Aspergillus sp. SCSIO 40435 from the South China Sea

摘要:

【目的】南海珊瑚共附生真菌Aspergillus sp.SCSIO 40435次级代谢产物分离鉴定及抑菌活性筛选。【方法】利用稀释涂布平板法分离珊瑚共附生真菌。采用单菌多代谢产物方法(one strain many compounds，OSMAC)对分离菌株进行化学多样性筛选，并采用滤纸片扩散法对真菌发酵产物进行抑菌活性分析。通过ITS测序鉴定活性菌株SCSIO 40435的分类地位，运用多种色谱手段从其粗提物中分离纯化单体化合物，并利用各种波谱手段(HRESIMS、1D和2D NMR、单晶X-ray衍射法等)确定化合物的结构。最后，采用微量肉汤稀释法对单体化合物的抑菌活性进行评估。【结果】从南海珊瑚样品中分离得到19株共附生真菌，结合化学多样性和抑菌活性分析，筛选出1株产物丰富且具有多种抑菌活性的菌株SCSIO 40435。利用ITS测序分析将其鉴定为曲霉属真菌(Aspergillus sp.)，进一步从其发酵产物中分离鉴定了4个对三联苯类化合物：dicandidusin A (1)、candidusin A (2)、terphenyllin (3)和4″-deoxyterphenyllin (4)，其中化合物1为一个对三联苯同源二聚体类新化合物。此外，首次对化合物4的单晶结构进行了报道。【结论】本研究表明，南海珊瑚中含有丰富的共附生真菌资源，且具有产生结构新颖的活性次级代谢产物的潜力，有望成为药物发现和开发的重要来源。

关键词:珊瑚共附生真菌;活性次级代谢产物;对三联苯二聚体

Abstract:

[Objective] To investigate the antimicrobial activity and secondary metabolites from the coral-derived fungus Aspergillus sp. SCSIO 40435. [Methods] The coral-associated fungi were isolated by dilution-plating method. One strain-many compounds (OSMAC) approach was used for the analysis of metabolite diversity, and the antibacterial activities of fungal metabolites were tested via the standard disk diffusion method. The bioactive strain SCSIO 40435 was identified by rDNA ITS sequence analysis. The active metabolites of Aspergillus sp. SCSIO 40435 were isolated and purified from the crude extract by chromatographic methods, and their chemical structures were characterized by HRESIMS, 1D and 2D NMR, and single crystal X-ray diffraction analysis. The antibacterial activities of the isolated compounds were measured by the broth microdilution method. [Results] A total of 19 fungal strains were isolated from corals in the South China Sea. The strain SCSIO 40435 with abundant products and multiple antibacterial activities was screened out and identified as Aspergillus sp. SCSIO 40435. Four p-terphenyl compounds were isolated from the crude extract of Aspergillus sp. SCSIO 40435 and identified as dicandidusin A (1), candidusin A (2), terphenyllin (3), and 4″-deoxyterphenyllin (4), among which compound 1 is a new p-terphenyl homodimer. In addition, the single crystal structure of compound 4 was obtained for the first time. [Conclusion] This study demonstrates that corals from the South China Sea are rich in fungal resources and have the potential to produce novel active secondary metabolites, which are expected to become an important source for drug discovery and development.

Key words:coral-associated fungi;active secondary metabolites;p-terphenyl dimer