title: Kinetic study of the quenching reaction of singlet oxygen by common synthetic antioxidants (tert-butylhydroxyanisol, tert-di-butylhydroxytoluene, and tert-butylhydroquinone) as compared with alpha-tocopherol.
abstract: Effects of synthetic phenolic antioxidants (BHA, BHT, and TBHQ) on the methylene blue (MB) sensitized photooxidation of linoleic acid as compared with that of alpha-tocopherol have been studied. Their antioxidative mechanism was studied by both ESR spectroscopy in a 2,2,6,6-tetramethylpiperidone (TMPD)-methylene blue (MB) system and spectroscopic analysis of rubrene oxidation induced by a chemical source of singlet oxygen. Total singlet oxygen quenching rate constants (k(ox-Q)+k(q)) were determined using a steady state kinetic equation. TBHQ showed the strongest protective activity against the MB sensitized photooxidation of linoleic acid, followed by BHA and BHT. TBHQ (1 x 10(-3) M) exhibited 86.5% and 71.4% inhibition of peroxide and conjugated diene formations, respectively, in linoleic acid photooxidation after 60-min light illumination. The protective activity of TBHQ against the photosensitized oxidation of linoleic acid was almost comparable to that of alpha-tocopherol. The data obtained from ESR and rubrene oxidation studies clearly showed the strong singlet oxygen quenching ability of TBHQ. The k(ox-Q)+k(q) of BHA, BHT, and TBHQ were determined to be 3.37 x 10(7), 4.26 x 10(6), and 1.67 x 10(8) M(-1) s(-1), respectively. The k(ox-Q)+k(q) of TBHQ was within the same order of magnitude of that of alpha-tocopherol, a known efficient singlet oxygen quencher. There was a high negative correlation (r(2) = -0.991) between log (k(ox-Q)+k(q)) and reported oxidation potentials for the synthetic antioxidants, indicating their charge-transfer mechanism for singlet oxygen quenching. This is the 1st report on the kinetic study on k(ox-Q)+k(q) of TBHQ in methanol as compared with other commonly used commercial synthetic antioxidants and alpha-tocopherol.
authors: Dept. of Biomaterials Science and Engineering, Yonsei Univ., Seoul, Republic of Korea.
authors: Ji In
authors: JI
authors: Kim
authors: Jun Hyun
authors: JH
authors: Lee
authors: Dong Seong
authors: DS
authors: Choi
authors: Bo Mi
authors: BM
authors: Won
authors: Mun Yhung
authors: MY
authors: Jung
authors: Jiyong
authors: J
authors: Park
mesh_terms: D000975:Antioxidants / Q000494:pharmacology*; D002083:Butylated Hydroxyanisole / Q000494:pharmacology; D002084:Butylated Hydroxytoluene / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D006873:Hydroquinones / Q000494:pharmacology; D007700:Kinetics; D008027:Light; D019787:Linoleic Acid / Q000378:metabolism*; D008751:Methylene Blue / Q000378:metabolism; D009279:Naphthacenes / Q000378:metabolism; D010084:Oxidation-Reduction; D010777:Photochemistry / Q000379:methods; D010782:Photolysis; D026082:Singlet Oxygen / Q000378:metabolism*; D024502:alpha-Tocopherol / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D006873:Hydroquinones; D009279:Naphthacenes; D026082:Singlet Oxygen; D002084:Butylated Hydroxytoluene; D002083:Butylated Hydroxyanisole; C045049:rubrene; D019787:Linoleic Acid; C018855:2-tert-butylhydroquinone; D024502:alpha-Tocopherol; D008751:Methylene Blue