Malacinones A and B, two novel sesquiterpenoids with 6/6/5 tricyclic ring system from the agarwood of Aquilaria malaccensis

Two novel cadinane-type sesquiterpenoids, named as malacinones A (1) and B (2), with an unprecedented tricyclic 6/6/5 ring system have been isolated from the agarwood of Aquilaria malaccensis. Their structures were elucidated by the various spectroscopic data (IR, MS, 1D, and 2D NMR) analysis and the absolute configurations were determined by the electronic circular dichroism (ECD) spectroscopic data analysis. A plausible biosynthetic pathway of malacinones A and B was proposed. (C) 2019 Elsevier Ltd. All rights reserved.