TY - JOUR
T1 - Riboflavin-Photosensitized Oxidation Is Enhanced by Conjugation in Unsaturated Lipids
AU - Cardoso, Daniel R.
AU - Scurachio, Regina S.
AU - Santos, Willy G.
AU - Homem-de-Mello, Paula
AU - Skibsted, Leif Horsfelt
PY - 2013/3/6
Y1 - 2013/3/6
N2 - Methyl esters of polyunsaturated fatty acids were found to quench triplet-excited riboflavin (3Rib) in efficient bimolecular reactions with rate constants, as determined by laser flash photolysis, linearly depending upon the number of bis-allylic methylene (from 1 to 5). Deactivation of 3Rib is predicted by combining the experimental second-order rate constants k2 determined for acetonitrile/water (8:2, v/v) at 25 °C with density functional theory (DFT) calculations of bond dissociation energy to have an upper limiting value of 1.22 × 107 L mol -1 s-1 for hydrogen abstraction from bis-allylic methylene groups in unsaturated lipid by 3Rib. Still, ergosterol was found to deactivate 3Rib with k2 = 6.2 × 108 L mol-1 s-1, which is more efficient than cholesterol, with 6.9 × 107 L mol-1 s-1. Likewise conjugated (9E,11E) methyl linoleate (CLA) reacts with 3.3 × 10 7 L mol-1 s-1, 30 times more efficient than previously found for methyl α-linolenate. Conjugation as in CLA and ergosterol is concluded to enhance 3Rib deactivation, and dietary plant sterols and CLA may accordingly be important macronutrients for eye and skin health, protecting against light exposure through efficient deactivation of 3Rib.
AB - Methyl esters of polyunsaturated fatty acids were found to quench triplet-excited riboflavin (3Rib) in efficient bimolecular reactions with rate constants, as determined by laser flash photolysis, linearly depending upon the number of bis-allylic methylene (from 1 to 5). Deactivation of 3Rib is predicted by combining the experimental second-order rate constants k2 determined for acetonitrile/water (8:2, v/v) at 25 °C with density functional theory (DFT) calculations of bond dissociation energy to have an upper limiting value of 1.22 × 107 L mol -1 s-1 for hydrogen abstraction from bis-allylic methylene groups in unsaturated lipid by 3Rib. Still, ergosterol was found to deactivate 3Rib with k2 = 6.2 × 108 L mol-1 s-1, which is more efficient than cholesterol, with 6.9 × 107 L mol-1 s-1. Likewise conjugated (9E,11E) methyl linoleate (CLA) reacts with 3.3 × 10 7 L mol-1 s-1, 30 times more efficient than previously found for methyl α-linolenate. Conjugation as in CLA and ergosterol is concluded to enhance 3Rib deactivation, and dietary plant sterols and CLA may accordingly be important macronutrients for eye and skin health, protecting against light exposure through efficient deactivation of 3Rib.
U2 - 10.1021/jf305280x
DO - 10.1021/jf305280x
M3 - Journal article
C2 - 23402498
SN - 0021-8561
VL - 61
SP - 2883
EP - 2888
JO - Journal of Agricultural and Food Chemistry
JF - Journal of Agricultural and Food Chemistry
IS - 9
ER -