Selective cyclooxygenase-2 inhibitors from Calophyllum membranaceum

Chemical investigation of the anti-inflammatory Chinese folk medicine Calophyllum membranaceum has resulted in the isolation and characterization of three new xanthones (1-3), one new biphenyl C-glycoside (4), and one new phenylethanoid glycoside (5) along with 17 known compounds. Their structures were characterized on the basis of spectroscopic and chemical methods. Two xanthones, 2,6-dihydroxy-1,7-dimethoxyxanthone (1) and 3,4-dihydroxyxanthone, were found to exhibit selective inhibitory activity against cyclooxygenase-2 (IC50 = 2.99 and 1.80 mu M) in vitro.