title: Antioxidative and prooxidative effects of coumarin derivatives on free radical initiated and photosensitized peroxidation of human low-density lipoprotein.
abstract: The antioxidative and/or prooxidative activity of 4-methylcoumanrin (MC), 7-hydroxy-4-methylcoumarin (HMC) and 7,8-dihydroxy-4-methylcoumarin (DHMC), respectively, in the peroxidation of human low-density lipoprotein (LDL) has been studied. The peroxidation was initiated either thermally by water-soluble initiator 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH), or photochemically by a triplet sensitizer benzophenone (BP) or its water-soluble analogue disodium 3,3'-disulfobenzophenonate (DSBP). The reaction kinetics were monitored by the uptake of oxygen and the depletion of alpha-tocopherol (TOH) present in the native LDL. Kinetic analysis of the peroxidation process demonstrated that DHMC is a good antioxidant for both the AAPH-initiated and BP- and DSBP-photosensitized peroxidation; HMC is a prooxidant for the AAPH-initiated and DSBP-photosensitized peroxidation, but an antioxidant for the BP-sensitized peroxidation; MC is a prooxidant in all of these initiation conditions. The antioxidative action of the coumarin derivatives may include trapping the initiating radicals, trapping the propagating lipid peroxyl radicals, recycling alpha-tocopherol and/or deactivating the excited photosensitizer.
authors.affiliation: National Laboratory of Applied Organic Chemistry, Lanzhou University, Gansu, People's Republic of China.
authors.forename: Z Q
authors.initials: ZQ
authors.lastname: Liu
authors.forename: W
authors.initials: W
authors.lastname: Yu
authors.forename: Z L
authors.initials: ZL
authors.lastname: Liu
mesh_terms: D000578:Amidines / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology*; D001577:Benzophenones / Q000494:pharmacology*; D003374:Coumarins / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D015227:Lipid Peroxidation / Q000187:drug effects; D008075:Lipoproteins, HDL / Q000097:blood / Q000187:drug effects*; D016877:Oxidants / Q000494:pharmacology*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D000578:Amidines; D000975:Antioxidants; D001577:Benzophenones; D003374:Coumarins; D008075:Lipoproteins, HDL; D016877:Oxidants; D017319:Photosensitizing Agents; C047723:benzophenone; C046728:2,2'-azobis(2-amidinopropane)