Xanthones in mangosteen posses anti-inflammatory activity and the most active one is GM-1. The detailed study of GM-1 for its anti-inflammation and analgesia showed that GM-1 exhibited stronger anti-inflammatory activity three times over that of aspirin as seen in carrageenin-induced rat paw edema, rat pleurisy and on the primary lesion of adjuvant-induced arthritis models. In addition GM-1 also showed inhibitory activity in chronic inflammation as found in cotton pellet-induced granuloma formation and on the secondary lesion of adjuvant-induced arthritis in rats. Furthermore GM-1 elicited analgesic effect when tested in acetylcholine-induced writhing response in mice. The investigation of analgesic effect of the products from mangosteen (as food supplement) in volunteers with joint pain and gastric ulcer will also be presented.