Xanthones are biologically active plant phenols--with powerful antioxidant compounds, more potent than vitamins C and E--found in great abundance in the fruit of the mangosteen (Garcinia mangostana). The mangosteen fruit, or pericarp, contains more than 30 xanthones. Not only do xanthones help scavenge cell-damaging free radicals, they may also help enhance the immune system, regulate cholesterol, reduce inflammation, support the gastrointestinal system, and reduce fatigue.