Iron ions chelation-based antioxidant potential vs. pro-oxidant risk of ferulic acid: A DFT study in aqueous phase

A Review on Coordination Properties of Al(III) and Fe(III) toward Natural Antioxidant Molecules: Experimental and Theoretical Insights

“…The simulated electronic spectra showed a red shift of 35 and 27 nm for the two complexes, respectively, and the former perfectly fits the experimental observation[54], as evident from Figure1. Similar to the outcomes of Truong et al[50] about FA, the obtained ∆G f suggests a higher affinity of CA for ferrous ions rather than for the ferric one[47].…”

“…The stability of these species is relatively high, particularly when compared to the constant's value for the Fe(III)-HCCA complex (see Tables 1 and 2). The sequestering ability of HCCA toward the Al(III) cation was higher [50]. On these complexes, we performed TDDFT calculations to get an indication of the changes in the absorption spectrum of the ligand after the complexation.…”

“…The ability of chelating agents to block metal-related damage has been widely explored over the past ten years and even earlier by applying quantum mechanics-based approaches [ 13 , 14 , 18 , 31 , 34 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ]. In particular, DFT and its time dependent (TD) extension have been used to identify binding sites and complex stoichiometry, structurally characterizing the ligand–metal complexes, and comparing the outcomes with the available experimental data.…”

“…All the ligands considered in this review present more than one possible mono coordinating or chelating site, as highlighted in Scheme 1 by red circles and dashed arcs. Furthermore, to identify the most probable complexes in an aqueous environment, neutral and anionic species were taken into consideration as plausible ligands depending on the experiments or simulation conditions for complex formation [ 47 , 50 , 51 ]. From a modeling point of view, despite the wide literature on the complex formation of different antioxidants with several metal ions [ 18 , 52 , 53 ], only a few of these take into consideration the aqueous physiological environment and thus consider the metal ion surrounded by solvent molecules [ 13 , 14 , 31 , 34 , 45 , 47 , 51 ].…”

“…H-NMR doublet of the b proton of caffeic acid at pH = 3.5 and the deshielding effect caused by the formation of the complex with Al(III). Reproduced from[14] with permission from the Centre National de la Recherche Scientifique (CNRS) and the Royal Society of Chemistry.Regarding the Fe(III) complexation, no experimental structural characterization is available for CA and p-CA while the carboxylate anion was found as the most abundant species for FA in the complexes formed under a physiological environment in a computational work by Truong et al They explored several complexes and concluded that the most stable ones involved the coordination of Fe(III) on site A of FA and are of the type [M(H 2 O) 4 (L)] 2+ and [M(H 2 O) 2 (L) 2 ] + for 1:1 and 1:2 metal to ligand stoichiometric ratios, respectively[50]. On these complexes, we performed TDDFT calculations to get an indication of the changes in the absorption spectrum of the ligand after the complexation.…”