Guided by the UPLC-ESIMS profile, seven previously undescribed halogenated dihydroisocoumarins, palmaerones A-G, along with eleven known dihydroisocoumarins, were isolated from Lachnum palmae, an endophytic fungus from Przewalskia tangutica by exposure to a histone deacetylase inhibitor SAHA. Structures of the isolates were elucidated by analysis of their NMR, MS and optical rotation values. The antimicrobial, anti-inflammatory and cytotoxic activities of palmaerones A-G were evaluated. Palmaerones A-G showed antimicrobial activities against the strains (C. neoformans, Penicillium sp., C. albicans, B. subtilis and S. aureus), and palmaerone E exhibited potential antimicrobial activities against all the test strains with the MIC value in the range of 10-55 μg/mL. Palmaerones A and E exhibited moderate inhibitory effects on NO production in LPS-induced RAW 264.7 cells, with the IC50 values of 26.3 and 38.7 μM, respectively and no obvious toxicities were observed at 50 μM. Palmaerone E showed weak cytotoxicity against HepG2 with the IC50 value of 42.8 μM. This work provides an effective strategy for expanding natural product resource.

中文翻译：

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从 Przewalskia tangutica 中分离的内生真菌 Lachnum palmae 产生的生物活性卤化二氢异香豆素

在 UPLC-ESIMS 配置文件的指导下，通过暴露于组蛋白去乙酰化酶抑制剂 SAHA，从 Lachnum palmae（一种来自 Przewalskia tangutica 的内生真菌）中分离出 7 种以前未描述的卤化二氢异香豆素、palmaerones AG 和 11 种已知的二氢异香豆素。通过分析它们的NMR、MS和旋光度值来阐明分离物的结构。评估了palmaerones AG 的抗菌、抗炎和细胞毒活性。Palmaerones AG 对菌株（新型念珠菌、青霉属、白色念珠菌、枯草芽孢杆菌和金黄色葡萄球菌）表现出抗菌活性，而palmaerone E 对所有测试菌株均表现出潜在的抗菌活性，MIC 值在10-55 μg/mL。Palmaerones A 和 E 对 LPS 诱导的 RAW 264.7 细胞中的 NO 产生表现出中等抑制作用，IC50 值分别为 26.3 和 38.7 μM，在 50 μM 下未观察到明显的毒性。Palmaerone E 对 HepG2 显示出微弱的细胞毒性，IC50 值为 42.8 μM。这项工作为扩大天然产物资源提供了有效的策略。