Xanthones are yellow pigments in flowers. Xanthones with the basic molecular formula C13H8O2 are flavonoids and are found in some fruit and bark of tree, but the highest concentration is found in the pericarp of the mangosteen fruit. Xanthones from mangosteen have been reported as antioxidant, antibacterial especially for Mycobacterium tuberculosis and anticancer.
Many are polyketide derived, although others are formed from combined shikimic acid pathways combined with acetate-malonate units.
Three units of malonate react with a hydroxybenzoic acid (C6-C1). Benzophenones may be converted by oxidative rings closure into xanthones.
Several xanthones that possess antidepressant activity inhibit monoamine oxidases. These compounds have in vitro cytotoxicity and in vivo antitumor activity. Xanthones kill microbes, improve depression, stimulate the production of urine and improve the function of the heart.
Xanthones isolated from natural sources are classified into six main groups, namely, simple xanthones, xanthone glycosides, prenylated xanthones, xanthonolignoids, bisxanthones, and miscellaneous xanthones.
Polyphenolic compounds of xanthones
