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

Antioxidant activities based on iron ions chelation of ferulic acid (FA) in competition with its pro-oxidant risk have been investigated. Reaction enthalpies (Delta(r)G(0)) and Gibbs free energies (Delta H-r(0)) of chelation reaction between the neutral (H(2)A) 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 H(2)A 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 O-2(center dot -) 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.