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

[Display omitted] •Fe(II) and Fe(III) ions chelation based antioxidant of ferulic acid were performed.•Pro-oxidant risk was evaluated by DFT via reduction of Fe(III)-to-Fe(II) complexes.•An evident competition of antioxidant activities and pro-oxidant risk is observed.•Chelation of Fe(III) ion is more favorable than the one of Fe(II) ion.•Pro-oxidant based on reduction of Fe(III)-to-Fe(II) is spontaneous and exergonic. Antioxidant activities based on iron ions chelation of ferulic acid (FA) in competition with its pro-oxidant risk have been investigated. Reaction enthalpies (ΔrH0) and Gibbs free energies (ΔrG0) of chelation reaction between the neutral (H2A) and mono-anionic (HA−) forms with [Fe(H2O)6]2+ and [Fe(H2O)6]3+ were computed in aqueous phase by employing DFT method at the M05/6-311++G(3df,2p)//M05/6-311++G(d,p) level of theory. As a result, the Fe(III) ion chelation is more favorable than the Fe(II) one. HA− coordinates with the iron ions better than H2A with the carboxylic group being the main coordination site. The pro-oxidant risk based on reduction reactions from Fe(III) to Fe(II) complexes using ascorbate anion (Asc−) and superoxide radical anion O2− as reducing agents was also investigated. It shows that all the reduction reactions are spontaneous and exergonic. The antioxidant activities are generally more preponderant than the pro-oxidant risk, although the latter becomes considerable in some specific conditions.