珊瑚礁泥砂真菌多样性及真菌Cladosporium sp. GXIMD02067天然产物分离与鉴定

Fungal diversity in coral reef sand and separation and identification of the natural products from Cladosporium sp. GXIMD02067

摘要:

【背景】海洋沉积物真菌富含生物活性天然产物，但珊瑚礁泥砂真菌及其天然产物的研究较少。【目的】分离珊瑚礁泥砂真菌及其天然产物，探究珊瑚礁泥砂来源真菌多样性，为海洋真菌天然产物开发奠定基础。【方法】采用稀释涂布平板法分离珊瑚礁泥砂真菌并基于ITS rDNA序列分析鉴定真菌；综合运用硅胶柱、反相柱和制备HPLC色谱技术分离枝孢属真菌(Cladosporium sp.) GXIMD02067的天然产物，通过核磁共振波谱技术和文献数据比对鉴定化合物结构。【结果】19株真菌被分离，隶属1纲4目4科6属，包括7株曲霉属(Aspergillus)、6株青霉属(Penicillium)、2株枝孢属(Cladosporium)、1株蜡蚧菌属(Lecanicillium)、2株路霉属(Lulworthia)和1株Parengyodontium。GXIMD02065和GXIMD02066 ITS rDNA序列的相似度小于87%，是潜在新菌种。7个化合物从Cladosporium sp. GXIMD02067中分离并鉴定为pyrenocine A (1)、pyrenocine B (2)、胸腺嘧啶脱氧核苷(3)、1H-吲哚-3-甲醛(4)、对羟基苯甲酸(5)、对羟基苯乙酸甲酯(6)和对羟基苯甲醛(7)。化合物1对表皮葡萄球菌、粘性放线菌的MIC值为62.5μg/mL，对枯草芽孢杆菌的MIC值为125 μg/mL，其他化合物在测试浓度下未显示抗菌活性。化合物1-7在测试浓度下未显示α-葡萄糖苷酶抑制活性。【结论】本研究报道了珊瑚礁泥砂真菌多样性和该海域微生物的天然产物，丰富了珊瑚礁泥砂真菌的种类和天然产物的多样性，为进一步研究珊瑚礁泥砂真菌的活性天然产物奠定了基础。

关键词:海洋真菌;珊瑚礁;枝孢属;天然产物;抗菌

Abstract:

[Background] The fungi in marine sediments are rich in bioactive natural products, while little is known about the fungi in coral reef sand and their natural products. [Objective] To isolate fungi from coral reef sand and separate their natural products, explore the fungal diversity, and lay a foundation for the development of natural products from marine fungi. [Methods] The fungi from coral reef sand were isolated with the dilution-plate method and identified based on the ITS rDNA sequences. The natural products of Cladosporium sp. GXIMD02067 were separated by silica gel column, reversed phase column, and preparative HPLC. The chemical structures of natural products were identified by nuclear magnetic resonance spectroscopy and comparison with literature data. [Results] Nineteen fungal strains belonging to 6 genera, 4 families, 4 orders, and 1 class were isolated, including 7 strains of Aspergillus, 6 strains of Penicillium, 2 strains of Cladosporium, 1 strain of Lecanicillium, 2 strains of Lulworthia, and 1 strain of Parengyodontium. GXIMD02065 and GXIMD02066 shared the ITS rDNA sequence similarity less than 87%, which indicated that they may be new strains. Seven compounds were separated from Cladosporium sp. GXIMD02067 and identified as pyrenocine A (1), pyrenocine B (2), thymidine (3), 1H-indole-3-carbaldehyde (4), p-hydroxybenzoic acid (5), methyl 2-(4-hydroxyphenyl)acetate (6), and p-hydroxybenzaldehyde (7). Compound 1 showed inhibitory activities against Staphylococcus epidermidis, Actinomyces viscosus, and Bacillus subtilis, with the minimal inhibitory concentrations of 62.5, 62.5, and 125μg/mL, respectively, while other compounds were inactive at the test concentrations. Compounds 1–7 demonstrated no inhibitory activities against a-glucosidase. [Conclusion] The paper reported the fungi from coral reef sand and their natural products for the first time, which enriched the knowledge about the diversity of fungi in coral reef sand and their natural products and laid a foundation for further research on such active natural products.

Key words:marine fungi;coral reef;Cladosporium;natural products;antimicrobial activity