Modelling of Protective Mechanism of Iron(II)-polyphenol Binding with OH-related Molecular Descriptors

The linear models for the calculation of pIC(50), pK(a1) and Ep(a) for 12 polyphenolic compounds (catechins, flavonols, catechol and gallol derivatives) were developed. As descriptors we used the number of vicinal (N-v) and non-vicinal (N-nv) OH groups, as well as the number of OH vicinal pairs as possible Fe2+ chelate sites (N-ch). The models gave r > 0.9 and standard errors of 0.13, 0.26 and 0.04 for pIC(50), pK(a1) and Ep(a), respectively. For modelling of pIC(50), Nch is better variable than Nv, and vice versa for modelling of pKa1 and Epa. This result, along with good correlations between pIC(50), pK(a1) and Ep(a), suggests two effects for antioxidative activity of polyphenols; their reaction(s) with OH and prevention of Fenton reaction by Fe2+ chelation.