title: Plasma HDL reduces nonesterified fatty acid hydroperoxides originating from oxidized LDL: a mechanism for its antioxidant ability.
abstract: The antioxidant property of plasma high-density lipoprotein (HDL) is thought to be involved in potential anti-atherogenic effects but the exact mechanism is not known. We aimed to reveal the contribution of HDL on the elimination of lipid hydroperoxides (LOOH) derived from oxidized low-density lipoprotein (LDL). Oxidized LDL prepared by copper ion-induced oxidation contained nonesterified fatty acid hydroperoxides (FFA-OOH) and lysophosphatidylcholine (lysoPtdCho), in addition to cholesteryl ester hydroperoxides (CE-OOH) and phosphatidylcholine hydroperoxides (PtdCho-OOH). A platelet-activating factor-acetylhydrolase (PAF-AH) inhibitor suppressed formation of FFA-OOH and lysoPtdCho in oxidized LDL. Among LOOH species, FFA-OOH was preferentially reduced by incubating oxidized LDL with HDL. HDL exhibited selective FFA-OOH reducing ability if it was mixed with a liposomal solution containing FFA-OOH, CE-OOH and PtdCho-OOH. Two-electron reduction of the hydroperoxy group to the hydroxy group was confirmed by the formation of 13-hydroxyoctadecadienoic acid from 13-hydroperoxyoctadecadienoic acid in HPLC analyses. This reducing effect was also found in apolipoprotein A-1 (apoA-1). FFA-OOH released from PtdCho-OOH due to PAF-AH activity in oxidized LDL undergo two-electron reduction by the reducing ability of apoA1 in HDL. This preferential reduction of FFA-OOH may participate in the mechanism of the antioxidant property of HDL.
authors.affiliation: Department of Food Science, Institute of Health Biosciences, University of Tokushima Graduate School, Kuramoto-cho 3-18-15, Tokushima 770-8503, Japan.
authors.forename: Mari
authors.initials: M
authors.lastname: Kotosai
authors.forename: Sachiko
authors.initials: S
authors.lastname: Shimada
authors.forename: Mai
authors.initials: M
authors.lastname: Kanda
authors.forename: Namiko
authors.initials: N
authors.lastname: Matsuda
authors.forename: Keiko
authors.initials: K
authors.lastname: Sekido
authors.forename: Yoshibumi
authors.initials: Y
authors.lastname: Shimizu
authors.forename: Akira
authors.initials: A
authors.lastname: Tokumura
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Nakamura
authors.forename: Kaeko
authors.initials: K
authors.lastname: Murota
authors.forename: Yoshichika
authors.initials: Y
authors.lastname: Kawai
authors.forename: Junji
authors.initials: J
authors.lastname: Terao
mesh_terms: D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism*; D016632:Apolipoprotein A-I / Q000378:metabolism; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D006801:Humans; D008054:Lipid Peroxides / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism*; D010084:Oxidation-Reduction
chemical_list: D000975:Antioxidants; D016632:Apolipoprotein A-I; D005230:Fatty Acids, Nonesterified; D008054:Lipid Peroxides; D008075:Lipoproteins, HDL; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase