LAUSR

Abstract Ochuscins A‒G (1–7), seven highly oxygenated usnic acid derivatives were isolated from the deep-sea-derived fungus Ochroconis sp. FS449. Their structures were elucidated based on the 1D, 2D NMR, HRESIMS and single crystal X-ray diffraction, while the absolute configurations were established by the quantum chemical calculations of 13C NMR chemical shifts as well as ECD plots. The biosynthesis pathway of 1‒7 was proposed to generate via a dimerization of phloroglucinol derivatives. In the bioassay, compounds 2, 3, 4 and 7 exhibited moderate inhibitory activities against acetylcholinesterase with the IC50 values in the range from 49 to 80 μM. A preliminary structure-activity relationship was discussed.