Abstract

Two novel koninginin derivatives, koningipyridines A and B (1 and 2), along with four known compounds (3˗6) were isolated from the EtOAc extract of the endophytic fungus Trichoderma koningiopsis SC-5. Among them, koningipyridine A featured an unprecedented pentacyclic ketal skeleton with the formation of a fascinating 6/6/5/6/5 fused ring system and shared a characteristic pyridine core, which represents the first example of nitrogen-containing koninginin-type natural product. Moreover, koningipyridine B was the first member in the koninginin family sharing a unique 6/6/5 dihydropyridine skeleton, and it was suggested to be the critical biosynthetic precursor of koningipyridine A. The structures of 1 and 2 were elucidated by the interpretation of 1D and 2D NMR spectroscopy, HRESIMS data, as well as theoretical calculations of ¹³C NMR and electronic circular dichroism (ECD). Moreover, all isolates were screened for antimicrobial activities against Staphylococcus aureus, MRSA, and Escherichia coli as well as the cytotoxic effects against three cancer cell lines (A549, Hela, and HepG2).

Graphical Abstract

中文翻译：

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Koningipyridines A 和 B，两种来自真菌 Trichoderma koningiopsis SC-5 的含氮聚酮化合物

摘要

从内生真菌Trichoderma koningiopsis SC-5的 EtOAc 提取物中分离出两种新型 koninginin 衍生物，koningipyridines A 和 B（1和2）以及四种已知化合物（3˗6 ） 。其中，koningipyridine A具有前所未有的五环缩酮骨架，形成令人着迷的6/6/5/6/5稠环体系，并共享一个特征性的吡啶核心，这是第一个含氮koninginin型天然产物的例子。此外，koningipyridine B是koningipyridine家族中第一个具有独特6/6/5二氢吡啶骨架的成员，被认为是koningipyridine A的关键生物合成前体。通过1D的解释阐明了1和2的结构和 2D NMR 光谱、HRESIMS 数据以及¹³ C NMR 和电子圆二色性 (ECD) 的理论计算。此外，还筛选了所有分离株对金黄色葡萄球菌、MRSA 和大肠杆菌的抗菌活性以及对三种癌细胞系（A549、Hela 和 HepG2）的细胞毒性作用。

图形概要