Recent advances in cassane diterpenoids: structural diversity and biological activities

Cassane diterpenoids are naturally occurring compounds, characterized mainly by molecular skeletons of three fused cyclohexane rings. They are predominantly isolated from the genus <i>Caesalpinia</i> (<i>Fabaceae</i>). Cassane diterpenoids possess various pharmacological activities, including anti-inflammatory, antibacterial, cytotoxic, antiparasitic, antidiabetic, and neuroprotective effects. This work provides an update on the newly reported cassane diterpenoids from 2019 to 2025. In this work, cassane diterpenoids are categorized according to their carbon skeletons into usual tricyclic cassanes, tricyclic cassane with butanolide, cassane furanoditerpenoids, norcassanes, cassane ester amines, cassane amides, and penta-spiro cassanes. Their reported biological activities, together with biosynthetic pathways, isolation and purification, and structure-activity relationships, are discussed. A total of 238 compounds were discussed, and 55 references were listed. The reported findings expand the knowledge of chemical features and biological potential of cassane diterpenoids and support their further investigation as promising leads for drug discovery.