Abstract：
A novel polycyclic quinazoline alkaloid (1) along with one new natural quinoline alkaloid (2) and two known quinoline alkaloids (3,4) were isolated from the marine-derived fungus Trichoderma longibrachiatum QD01. Structural determinations of those isolates were established by comprehensive spectroscopic analyses and literature comparison. Single-crystal X-ray diffraction analysis of novel compound verified its structure and stereochemistry, representing the first characterised crystal structure of a trimeric-type of tetrahydroquinazoline. Compound 4 exhibited potential antibacterial and anti-quorum sensing activity against C. violaceum and C. violaceum CV026. The sub-MIC of 4 observably decreased the violacein production in C. violaceum CV026 by 55% on 15 μg/mL. Furthermore, molecular docking results revealed that 4 has stronger binding interactions with CviR receptor than ligand C6-HSL with lower binding energy of -8.68 kcal/mol. Hydrogen bond and π-π interactions formed by Trp84, Tyr88, Trp111, and Phe126 were predicted to play an important role in the inhibition against C. violaceum CV026.
摘要：
从海洋真菌长臂木霉QD01中分离出一种新型多环喹唑啉生物碱（1）以及一种新的天然喹啉生物碱（2）和两种已知的喹啉生物碱（3,4）。通过全面的光谱分析和文献比较确定了这些分离株的结构。新化合物的单晶X射线衍射分析证实了其结构和立体化学,代表四氢喹唑啉的三聚体型的第一个表征的晶体结构。化合物4对紫花苜蓿和紫花苜蓿CV026表现出潜在的抗菌和抗群体感应活性。在15μg/mL时，4的亚MIC可观察到使紫罗兰C.CV026中的紫罗兰素产量降低了55％。此外，分子对接结果表明，4与CviR受体的结合相互作用比配体C6-HSL更强，结合能低-8.68kcal/mol。预计由Trp84，Tyr88，Trp111和Phe126形成的氢键和π-π相互作用在抑制紫罗兰草CV026中起重要作用。
