A novel polycyclic quinazoline and three quinolines alkaloids from marine-derived fungus QD01 with anti-bacterial and anti-quorum sensing activities.

A novel polycyclic quinazoline alkaloid () along with one new natural quinoline alkaloid () and two known quinoline alkaloids (,) were isolated from the marine-derived fungus 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 exhibited potential antibacterial and anti-quorum sensing activity against and CV026. The sub-MIC of observably decreased the violacein production in CV026 by 55% on 15 g/mL. Furthermore, molecular docking results revealed that 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 CV026.