Xanthones are a newly discovered, class of biologically active polyphenolic compounds structurally similar to bioflavonoids.
In nature, xanthones are very restricted in occurrence. The majority of them are found in just two families of higher plants – Guttiferae and Gentianaceae. Over 200 naturally occurring xanthones have been identified so far. Approximately 40 of those are found in the mangosteen.
Xanthones are biologically active molecules with a six-carbon conjugated ring structure characterized by multiple double carbon bonds. The bonds make the xanthone molecule very stable.
All xanthones possess the same structural backbone. What makes the various xanthones unique are the side chains bound to the carbon molecules.
As examples of the xanthone’s versatility, note the various side chains that can be attached to the backbone.
Alpha mangostin, gamma mangostin, and Garcinone E are just three of the close to 40 xanthones in the mangosteen that provide the fruit with many of its medicinal properties.
Xanthones appear to possess numerous potential beneficial properties such as, “antiallergic, anti-inflammatory, antituberculotic, antitumor, antiplatelet, Betaadrenergic blocking and … anticonvulsant" properties. (Marona H, Pekala E, Filipek B, Maciag D, Szneler E. Pharmacological properties of some aminoalkanolic derivatives of xanthone. Pharmaxie. 2001;56:567-572)
More recent research has revealed that, while the xanthones appear to be the most nutritionally important elements in the mangosteen fruit, catechins, polysaccharides, proanthocyanidins and sterols also play major roles in providing the fruit with its unmatched medicinal qualities.
"Xanthones show considerable biological activity, and it is surprising that none has an established use in medicine." (Taylor, Frost. Phytochemical Dictionary; 1983.)