Asperversins A and B, Two Novel Meroterpenoids with an Unusual 5/6/6/6 Ring from the Marine-Derived Fungus Aspergillus versicolor

Asperversins A (1) and B (2), two novel meroterpenoids featuring an uncommon 5/6/6/6 ring system, along with five new analogues (3–7) and a known compound asperdemin (8), were obtained from the marine-derived fungus Aspergillus versicolor. Their structures and absolute configurations were confirmed by extensive spectroscopic analyses, single-crystal X-ray diffraction studies, and electronic circular dichroism (ECD) calculation. All new compounds were tested for their acetylcholinesterase enzyme (AChE) inhibitory activities and cytotoxic activities, of which compound 7 displayed moderate inhibitory activity against the AChE with an IC50 value of 13.6 μM.