Xanthones

Xanthones ( the root -xanthmeans yellow) are brightly-pigmented antioxidants that occur in only a few medicinal plants. The basic xanthone structure contains two phenolic rings fused to a central pyranone ring (hence the -one suffix).

St. John's Wort contains a variety of xanthones including norathyriol, which you can see in its bright, sunny yellow flowers. These compounds act synergistically with the other co-active molecules (hypericin, hyperforin, the flavonoids, etc.) to bring about Hypericum's antidepressant activity.

The mangostins are a group of closely-related xanthones that give Mangosteen (Garcinia mangostana) fruit a yellowish tinge; several animal studies have identified antimicrobial, antioxidant, anti-inflammatory (via COX-2 modulation), and cardioprotective effects. The mangostins, norathyriol and its glycoside, mangiferin, have also been found to have anticarcinogenic activities. Norathyriol, in particular, has potent anti-inflammatory properties. The latter two compounds are also found in the fruit of the Mango (Mangiferaspp.). Another potentially active xanthone is gentisein, one of the pigments found in Yellow Gentian (Gentiana lutea) and in some species of Hypericum. Although research is lacking, it has been speculated that gentisein may have activities similar to those of other xanthones. (-Ganora)

Xanthones could be useful in the treatment of multidrug resistant cancers.

Natural xanthones have multifunctional activities against Alzheimer's disease.

A review of the xanthones found in lichens.

Structure-Activity Relationship of Xanthones as Inhibitors of Xanthine Oxidase.