TY - JOUR
T1 - Chain length effects in isoflavonoid daidzein alkoxy derivatives as antioxidants
T2 - a quantum mechanical approach
AU - An, Cun-Bin
AU - Li, Dan
AU - Liang, Ran
AU - Bu, Ya-Zhong
AU - Wang, Sha
AU - Zhang, Er-Hai
AU - Wang, Peng
AU - Ai, Xi-Cheng
AU - Zhang, Jian-Ping
AU - Skibsted, Leif Horsfelt
PY - 2011/12/14
Y1 - 2011/12/14
N2 - Daidzein, an isoflavonoid with known prooxidative effects in heterogeneous lipid/water systems, changes to an antioxidant for 7-n-alkoxy derivatives of daidzein. For an alkyl length increasing from 4 to 8, 12, and 16 carbons, the oxidation potential decreases gradually from 1.09 V (vs NHE) for daidzein (D) to 0.94 V for D16 in tetrahydrofuran as determined by cyclic voltammetry at 25 °C. The prooxidative effects transform into antioxidative effects from D8 with a maximal effect for D12 for aqueous phase initiation of lipid oxidation in liposomes despite a gradual decrease in Trolox equivalent antioxidant capacity (TEAC) with increasing alkyl chain length. Quantum mechanical calculations using density functional theory (DFT) showed that the bond dissociation energy of the O-H bond of the 4′-phenol is constant along the homologue series in contrast to Δμ, the change in dipole moment upon hydrogen atom donation, which increases for increasing chain length. The frontier orbital energy gap goes through a maximum for D12. The change in the A-to-B dihedral angle upon hydrogen atom donation further shows a maximum for D12 of 6.45°. The importance of these microscopic properties for antioxidative activity was confirmed by a change in liposome fluorescence anisotropy using a fluorescent probe showing maximal penetration into the lipid bilayer for D12 along the homologue series.
AB - Daidzein, an isoflavonoid with known prooxidative effects in heterogeneous lipid/water systems, changes to an antioxidant for 7-n-alkoxy derivatives of daidzein. For an alkyl length increasing from 4 to 8, 12, and 16 carbons, the oxidation potential decreases gradually from 1.09 V (vs NHE) for daidzein (D) to 0.94 V for D16 in tetrahydrofuran as determined by cyclic voltammetry at 25 °C. The prooxidative effects transform into antioxidative effects from D8 with a maximal effect for D12 for aqueous phase initiation of lipid oxidation in liposomes despite a gradual decrease in Trolox equivalent antioxidant capacity (TEAC) with increasing alkyl chain length. Quantum mechanical calculations using density functional theory (DFT) showed that the bond dissociation energy of the O-H bond of the 4′-phenol is constant along the homologue series in contrast to Δμ, the change in dipole moment upon hydrogen atom donation, which increases for increasing chain length. The frontier orbital energy gap goes through a maximum for D12. The change in the A-to-B dihedral angle upon hydrogen atom donation further shows a maximum for D12 of 6.45°. The importance of these microscopic properties for antioxidative activity was confirmed by a change in liposome fluorescence anisotropy using a fluorescent probe showing maximal penetration into the lipid bilayer for D12 along the homologue series.
U2 - 10.1021/jf2030314
DO - 10.1021/jf2030314
M3 - Journal article
C2 - 22007884
SN - 0021-8561
VL - 59
SP - 12652
EP - 12657
JO - Journal of Agricultural and Food Chemistry
JF - Journal of Agricultural and Food Chemistry
IS - 23
ER -