Serrulatane diterpenoids: a review of their biosynthesis, chemical diversity, and biological significance in plants and marine organisms

Serrulatane diterpenoids represent a structurally unique and biologically significant class of natural products, predominantly found in various plant genera and marine organisms, such as soft corals. Characterized by a distinctive bicarbocyclic skeleton and diverse oxygenation patterns, these compounds arise via an unconventional biosynthetic pathway involving the cisoid nerylneryl diphosphate (NNPP) and class I terpene synthases, diverging from the typical geranylgeranyl diphosphate (GGPP)-dependent route common to most diterpenes. Exhibiting potent antiviral, cytotoxic, and antimicrobial activities, serrulatanes hold promise as leads for pharmaceutical development, while also serving as chemotaxonomic markers and ecological defense agents in both terrestrial and marine environments. This review comprehensively summarizes the current knowledge on the naturally occurring serrulatane diterpenoids reported to date, detailing their sources, structural features, and biological activities, and highlighting their importance in chemical ecology and drug discovery.