Structural diversity and biological activities of caged Garcinia xanthones: recent updates

Caged xanthones are a class of natural compounds with approximately 200 members that are commonly isolated from the Garcinia genus in the Clusiaceae (formerly Guttiferae) family. They are often characterized by a notable 4-oxa-tricyclo[4.3.1.03,7]dec-2-one (caged) architecture with a common xanthone backbone. Because most caged xanthones have potent anticancer properties, they have become a target of interest in natural product chemistry. The unique chemical architectures and increasingly identified biological importance of these compounds have stimulated many studies and intense interest in their isolation, biological evaluation and mechanistic studies. This review summarizes recent progress and development in the chemistry and biological activity of caged Garcinia xanthones and of several compounds of non-Garcinia origin, from the years 2008 to 2021, providing an in-depth discussion of their structural diversity and medicinal potential. A preliminary discussion on structure-activity relationships is also provided.