title: Inhibition of cyclooxygenase and prostaglandin E2 synthesis by gamma-mangostin, a xanthone derivative in mangosteen, in C6 rat glioma cells.
abstract: The fruit hull of mangosteen, Garcinia mangostana L., has been used for many years as a medicine for treatment of skin infection, wounds, and diarrhea in Southeast Asia. In the present study, we examined the effect of gamma-mangostin, a tetraoxygenated diprenylated xanthone contained in mangosteen, on arachidonic acid (AA) cascade in C6 rat glioma cells. gamma-Mangostin had a potent inhibitory activity of prostaglandin E2 (PGE2) release induced by A23187, a Ca2+ ionophore. The inhibition was concentration-dependent, with the IC50 value of about 5 microM. gamma-Mangostin had no inhibitory effect on A23187-induced phosphorylation of p42/p44 extracellular signal regulated kinase/mitogen-activated protein kinase or on the liberation of [14C]-AA from the cells labeled with [14C]-AA. However, gamma-mangostin concentration-dependently inhibited the conversion of AA to PGE2 in microsomal preparations, showing its possible inhibition of cyclooxygenase (COX). In enzyme assay in vitro, gamma-mangostin inhibited the activities of both constitutive COX (COX-1) and inducible COX (COX-2) in a concentration-dependent manner, with the IC50 values of about 0.8 and 2 microM, respectively. Lineweaver-Burk plot analysis indicated that gamma-mangostin competitively inhibited the activities of both COX-1 and -2. This study is a first demonstration that gamma-mangostin, a xanthone derivative, directly inhibits COX activity.
authors.affiliation: Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-ku, 980-8578, Sendai, Japan.
authors.forename: Keigo
authors.initials: K
authors.lastname: Nakatani
authors.forename: Norimichi
authors.initials: N
authors.lastname: Nakahata
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Arakawa
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Yasuda
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ohizumi
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D000001:Calcimycin / Q000494:pharmacology; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000096:biosynthesis*; D004347:Drug Interactions; D029762:Garcinia mangostana / Q000737:chemistry; D005910:Glioma; D017320:HIV Protease Inhibitors / Q000494:pharmacology; D007527:Isoenzymes / Q000096:biosynthesis* / Q000187:drug effects; D008565:Membrane Proteins; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000187:drug effects; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D051381:Rats; D014407:Tumor Cells, Cultured; D014966:Xanthenes / Q000737:chemistry / Q000494:pharmacology*; D044004:Xanthones
chemical_list: D017320:HIV Protease Inhibitors; D007527:Isoenzymes; D008565:Membrane Proteins; D011500:Protein Synthesis Inhibitors; D014966:Xanthenes; D044004:Xanthones; D016718:Arachidonic Acid; D000001:Calcimycin; C009689:xanthone; D051545:Cyclooxygenase 1; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; C496513:Ptgs1 protein, rat; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D015232:Dinoprostone; C021053:mangostin