Naturally occurring cassane diterpenoids (CAs) of Caesalpinia: A systematic review of its biosynthesis, chemistry and pharmacology

Natural products, especially diterpenoids, are enriched with numerous compounds with a broad spectrum of therapeutic indications, suggesting that functional moieties serve as a core pharmacophore. Cassane diterpenoids (CAs), as the main and characteristic constituents of medical plants in the Caesalpinia genus, have been widely studied due to their bioactivities, and >450 compounds have been reported since the 1960s, including 283 compounds that have been reported in the past decade. There are five main types of structures for these compounds: tricyclic cassane diterpenoids with a fused furan ring (I) or butanolide lactone (II), tricyclic cassane diterpenoids (III), norcassane diterpenoids (IV), and other types (V). CAs derivatives have a wide range of biological properties, including anti-inflammatory, antimalarial, antitumour, antiviral, antimicrobial, antinociceptive, and antioxidant effects. This review highlights the role of the biosynthetic pathway, including those with abnormal skeletons, as well as advances in structure, pharmacological activities and primarily mechanisms of CAs obtained from the Caesalpinia genus. The findings herein provide new insights into the development of this kind of natural diterpenoids.