Metabolites with Anti-acetylcholinesterase Activities from Marine Mesophotic Zone Halichondria Sponge-associated Fungus Chaetomium sp. NBUF152

Abstract

Background: Mesophotic coral ecosystems (MCEs) are light-dependent ecosystems found from 30 to 150 m in depth that are highly diverse and relatively understudied worldwide. Methods: One new indole alkaloid, chaetoid A (1), one known analog, indigodole B (2), and one known β-carboline type alkaloid 1-acetyl-β-carboline (3), along with three known cyclic depsipeptides, turnagainolide A (4), turnagainolide B (5), arthroamide (6)—were isolated from cultures of fungus Chaetomium sp. NBUF152 is associated with a 66 m deep mesophotic zone Halichondria sponge. Their structures were determined by analysis of spectroscopic data (NMR, HRESIMS, UV, IR, optical rotation, and ECD). The in vitro bioassay results showed that compounds 1-6 exhibited moderate inhibition against acetylcholinesterase (AchE). Results: The results showed that these compounds displayed moderate anti-AchE activities with IC50 values of 25.97 μmol/L, 25.80 μmol/L, 21.07 μmol/L, 23.49 μmol/L and 21.28 μmol/L, 25.3 μmol/L. Conclusion: This work could lead to additional investigation into the potential of marine organisms in MCEs as a source for discovering natural products with interesting structures and bioactivities.