Thirteen cyathane diterpenoids with acetylcholinesterase inhibitory effects from the fungus Cyathus africanus

Eight undescribed cyathane diterpenoids, representative specialised metabolites of the genus Cyathus, named cyathins Q-X, along with five known congeners, were isolated from the liquid fermentation of Cyathus africanus. Their structures and absolute configurations were elucidated by integrating NMR spectroscopic analyses, electronic circular dichroism (ECD) calculations, and X-ray diffraction. Reasonable correction to the C-12 configuration of cyathin I was corroborated by the crystal data. The structural identification in this research expanded the number of candidates to allow for more bioactivity-screening options. Among them, (12S)-11 alpha,14 alpha-epoxy13 alpha,14 beta,15-trihydroxycyath-3-ene displayed significant acetylcholinesterase (AChE) inhibitory effect with an IC50 value of 4.60 +/- 0.85 mu M. Molecular docking studies were also performed to unravel the underlying modes of interactions with the active sites of AChE for active compounds.