Fundación MEDINA, Avda. del conocimiento 34, 18016, Granada, Spain.
Departamento de Botánica, Facultad de Farmacia, Universidad de Granada, C/ Prof. Clavera, s/n, 18011, Granada, Spain.
Sci Rep. 2018 Jun 27;8(1):9729. doi: 10.1038/s41598-018-28192-5.
Native plant communities from arid areas present distinctive characteristics to survive in extreme conditions. The large number of poorly studied endemic plants represents a unique potential source for the discovery of novel fungal symbionts as well as host-specific endophytes not yet described. The addition of adsorptive polymeric resins in fungal fermentations has been seen to promote the production of new secondary metabolites and is a tool used consistently to generate new compounds with potential biological activities. A total of 349 fungal strains isolated from 63 selected plant species from arid ecosystems located in the southeast of the Iberian Peninsula, were characterized morphologically as well as based on their ITS/28S ribosomal gene sequences. The fungal community isolated was distributed among 19 orders including Basidiomycetes and Ascomycetes, being Pleosporales the most abundant order. In total, 107 different genera were identified being Neocamarosporium the genus most frequently isolated from these plants, followed by Preussia and Alternaria. Strains were grown in four different media in presence and absence of selected resins to promote chemical diversity generation of new secondary metabolites. Fermentation extracts were evaluated, looking for new antifungal activities against plant and human fungal pathogens, as well as, cytotoxic activities against the human liver cancer cell line HepG2. From the 349 isolates tested, 126 (36%) exhibited significant bioactivities including 58 strains with exclusive antifungal properties and 33 strains with exclusive activity against the HepG2 hepatocellular carcinoma cell line. After LCMS analysis, 68 known bioactive secondary metabolites could be identified as produced by 96 strains, and 12 likely unknown compounds were found in a subset of 14 fungal endophytes. The chemical profiles of the differential expression of induced activities were compared. As proof of concept, ten active secondary metabolites only produced in the presence of resins were purified and identified. The structures of three of these compounds were new and herein are elucidated.
干旱地区的本地植物群落具有独特的特征，可以在极端条件下生存。大量研究较少的特有植物代表了一个独特的潜在来源，可以发现新型真菌共生体以及尚未描述的宿主特异性内生菌。在真菌发酵中添加吸附性聚合物树脂已被证明可以促进新次生代谢产物的产生，并且是一种用于生成具有潜在生物活性的新化合物的常用工具。从位于伊比利亚半岛东南部干旱生态系统的 63 种选定植物中分离出的 349 株真菌菌株，根据形态特征和 ITS/28S 核糖体基因序列进行了特征描述。分离出的真菌群落分布在包括担子菌纲和子囊菌纲在内的 19 个目中，其中 Pleosporales 是最丰富的目。总共鉴定出 107 个不同的属，其中 Neocamarosporium 是从这些植物中最常分离到的属，其次是 Preussia 和 Alternaria。在存在和不存在选定树脂的情况下，将菌株在四种不同的培养基中培养，以促进新次生代谢物的化学多样性生成。评估发酵提取物，寻找针对植物和人类真菌病原体的新抗真菌活性，以及针对人肝癌细胞系 HepG2 的细胞毒性活性。在所测试的 349 株分离物中，有 126 株（36%）表现出显著的生物活性，包括 58 株具有独特抗真菌特性的菌株和 33 株对 HepG2 肝癌细胞系具有独特活性的菌株。通过 LCMS 分析，可鉴定出 96 株菌产生的 68 种已知生物活性次生代谢物，并且在 14 株真菌内生菌的亚组中发现了 12 种可能未知的化合物。比较了诱导活性差异的化学特征表达。作为概念验证，从仅在树脂存在下产生的 10 种活性次生代谢物中纯化并鉴定了这些次生代谢物。其中三种化合物的结构是新的，并在此阐明。
