Chemistry and biological activity of vibsane-type diterpenes

Plants producing natural products remain one of the few sources of drug discovery, yielding unorthodox and often unexpected chemical structures. Since some classes of plant-derived natural products are frequently concentrated on the same genus, the extensive chemosysternatic studies of the specific plants serve as a chemical library to discover candidates for drugs or biological probes for physiological studies. Vibsane-type diterpenes belong to rarely occurring natural products since they have been elaborated solely in Viburnum species such as V awabuki, V odoratissimum, and V suspensum. These diterpenes are further classified into 11-membered ring, 7-membered ring and rearranged (neovibsanin) types, thus putting their chemical diversity into a unique chemical library. We describe a variety of vibsanes, chemical correlations between three subtypes, and synthetic studies of vibsanin F, the simplest 11-membered ring vibsane, as well as neurotrophic activities of neovibsanins A-B.