Antioxidant activity of a Mg(II) compound containing ferulic acid as chelator: potential application for active packaging and riboflavin stabilisation

Food rich in riboflavin (Rf) are susceptible to degradation due to oxidative processes with the formation radicals. Here we describe the features and stability of a Mg(II) complex containing ferulic acid (fer) and 1,10-phenanthroline (phen) as chelators, henceforth Mg(phen)(fer). The electrochemical behavior of Mg(phen)(fer) is pH dependent and results from the stabilization of the corresponding phenoxyl radical via complexation with Mg(II). This stabilization enhances the antioxidant activity of Mg(phen)(fer) respecting the free fer and commercial antioxidants. Mg(phen)(fer) scavenges and neutralizes DPPH• (IC50 = 15.6 µmol/L), ABTS•+ (IC50 = 5.65 µmol/L), peroxyl radical (IC50 = 5.64 µg/L) and 1O2 (IC50 = 0.7 μg/m). The Mg(phen)(fer) effectively protects riboflavin (Rf) against photodegradation by quenching the singlet excited states of Rf regardless of the condition. Also, the complex Mg(phen)(fer) was effectively incorporated at starch films broadening its application as showed by microbiological studies. Thus, Mg(phen)(fer) has a high potential for use in Rf-rich foods and be a new alternative to the synthetic antioxidants currently used.