Neocucurbols A–H, Phomactin Diterpene Derivatives from the Marine-Derived Fungus Neocucurbitaria unguis-hominis FS685

Neocucurbols A–D (1–4) are diterpene derivatives that possess a complex 6/6/5/5/6 polycyclic ring system with a characteristic tetrahedrofuran bridge ring skeleton. Neocucurbols E–H (5–8) are diterpenes that feature a 6/8/6 tricyclic ring system. Their structures were unambiguously determined by detailed spectroscopic analyses, X-ray diffractions studies, and ECD calculations. All compounds (1–8) were evaluated for in vitro antimicrobial and cytotoxic activities.