TY - JOUR
T1 - Kinetics of iron oxidation upon polyphenol binding
AU - Perron, Nathan R.
AU - Wang, Hsiao C.
AU - Deguire, Sean N.
AU - Jenkins, Michael
AU - Lawson, Mereze
AU - Brumaghim, Julia L.
PY - 2010/11/7
Y1 - 2010/11/7
N2 - Polyphenol prevention of iron-mediated DNA damage occurs primarily through iron binding. Once bound, iron in the Fe2+-polyphenol complex autooxidizes to Fe3+ in the presence of O2. To determine the correlation between the rate of Fe2+-polyphenol autooxidation and polyphenol antioxidant ability, kinetic studies at pH = 6.0 in the presence of oxygen were performed using UV-vis spectrophotometry. Initial rates of iron-polyphenol complex oxidation for epigallocatechin gallate (EGCG), methyl-3,4,5-trihydroxybenzoate (MEGA), gallic acid (GA), epicatechin (EC), and methyl-3,4-dihydroxybenzoate (MEPCA) were in the range of 0.14-6.7 min -1. Polyphenols with gallol groups have faster rates of iron oxidation than their catechol analogs, suggesting that stronger iron binding results in faster iron oxidation. Concentrations of polyphenol, Fe2+, and O2 were varied to investigate the dependence of the Fe 2+-polyphenol autooxidation on these reactants for MEGA and MEPCA. For these analogous gallate and catecholate complexes of Fe2+, iron oxidation reactions were first order in Fe2+, polyphenol, and O 2, but gallate complexes show saturation behavior at much lower Fe2+ concentrations. Thus, gallol-containing polyphenols promote iron oxidation at a significantly faster rate than analogous catechol-containing compounds, and iron oxidation rate also correlates strongly with polyphenol inhibition of DNA damage for polyphenol compounds with a single iron-binding moiety.
AB - Polyphenol prevention of iron-mediated DNA damage occurs primarily through iron binding. Once bound, iron in the Fe2+-polyphenol complex autooxidizes to Fe3+ in the presence of O2. To determine the correlation between the rate of Fe2+-polyphenol autooxidation and polyphenol antioxidant ability, kinetic studies at pH = 6.0 in the presence of oxygen were performed using UV-vis spectrophotometry. Initial rates of iron-polyphenol complex oxidation for epigallocatechin gallate (EGCG), methyl-3,4,5-trihydroxybenzoate (MEGA), gallic acid (GA), epicatechin (EC), and methyl-3,4-dihydroxybenzoate (MEPCA) were in the range of 0.14-6.7 min -1. Polyphenols with gallol groups have faster rates of iron oxidation than their catechol analogs, suggesting that stronger iron binding results in faster iron oxidation. Concentrations of polyphenol, Fe2+, and O2 were varied to investigate the dependence of the Fe 2+-polyphenol autooxidation on these reactants for MEGA and MEPCA. For these analogous gallate and catecholate complexes of Fe2+, iron oxidation reactions were first order in Fe2+, polyphenol, and O 2, but gallate complexes show saturation behavior at much lower Fe2+ concentrations. Thus, gallol-containing polyphenols promote iron oxidation at a significantly faster rate than analogous catechol-containing compounds, and iron oxidation rate also correlates strongly with polyphenol inhibition of DNA damage for polyphenol compounds with a single iron-binding moiety.
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U2 - 10.1039/c0dt00752h
DO - 10.1039/c0dt00752h
M3 - Article
C2 - 20871896
AN - SCOPUS:77957911415
SN - 1477-9226
VL - 39
SP - 9982
EP - 9987
JO - Dalton Transactions
JF - Dalton Transactions
IS - 41
ER -