title: Antioxidant activities of probucol against lipid peroxidations.
abstract: The antioxidant activities of probucol were measured in the oxidations of methyl linoleate in homogeneous solution and soybean phosphatidylcholine liposomal membranes and also of low-density lipoproteins. When an excess amount of probucol was reacted with galvinoxyl, the EPR spectrum of galvinoxyl disappeared and a new triplet EPR signal was found: g = 2.0058 and aH(2H) = 0.14 mT. The identical EPR spectrum was observed when probucol was reacted with tert-butoxyl radical generated from di-tert-butylperoxy oxalate. This EPR signal disappeared rapidly when reacted with either alpha-tocopherol or 6-O-palmitoyl-ascorbic acid. Probucol suppressed the free-radical-mediated oxidations of methyl linoleate in hexane and in acetonitrile, in a dose-dependent manner. Its antioxidant activity was 17.5-fold less than that of alpha-tocopherol in hexane. Probucol incorporated into soybean phosphatidylcholine liposomes suppressed its oxidation. The antioxidant activity of probucol was less than that of alpha-tocopherol, but the difference between the two antioxidant activities was smaller in the membranes than in homogeneous solution. Probucol also suppressed the oxidation of low-density lipoprotein. Interestingly, probucol suppressed the oxidation of LDL as efficiently as alpha-tocopherol, implying that physical factors as well as chemical reactivity are important in determining the overall activity of antioxidant in low-density lipoprotein.
authors.affiliation: Department of Reaction Chemistry, Faculty of Engineering, University of Tokyo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Gotoh
authors.forename: K
authors.initials: K
authors.lastname: Shimizu
authors.forename: E
authors.initials: E
authors.lastname: Komuro
authors.forename: J
authors.initials: J
authors.lastname: Tsuchiya
authors.forename: N
authors.initials: N
authors.lastname: Noguchi
authors.forename: E
authors.initials: E
authors.lastname: Niki
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D001559:Benzhydryl Compounds / Q000737:chemistry; D003300:Copper; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals; D006586:Hexanes; D006801:Humans; D008041:Linoleic Acids / Q000737:chemistry; D015227:Lipid Peroxidation / Q000187:drug effects*; D008077:Lipoproteins, LDL / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry; D010084:Oxidation-Reduction / Q000187:drug effects; D010713:Phosphatidylcholines / Q000737:chemistry; D011341:Probucol / Q000737:chemistry / Q000494:pharmacology*; D014810:Vitamin E / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D001559:Benzhydryl Compounds; D005609:Free Radicals; D006586:Hexanes; D008041:Linoleic Acids; D008077:Lipoproteins, LDL; D008081:Liposomes; D010713:Phosphatidylcholines; C057590:phosphatidylcholine hydroperoxide; D014810:Vitamin E; C005575:methyl linoleate; D003300:Copper; D011341:Probucol; C029892:cupric chloride; C020338:galvinoxyl