In vitro antioxidant activity of dietary polyamines

The polyamines spermidine and spermine are molecules naturally present in food. The effect of polyamines on oxidative stability was studied by means of in vitro experimental models. The potential antioxidant activity of polyamines compared to other antioxidants was investigated in both lipophilic and hydrophilic media by the DPPH method. Although antioxidant capacity was observed in both media, it was stronger in the lipophilic matrix. Thus, soybean oil was used as an in vitro model to study the concentration-dependent response of polyamines, which showed a strong antioxidant capacity at a wide range of concentrations (from 30 to 1250 mu g/mL). The antioxidant activity of polyamines was also studied in comparison with other antioxidants (octyl galate, a-tocopherol and palmitoyl ascorbate) at different points of the oxidation process: formation of peroxides, conjugated compounds, carbonylic and volatile compounds. Both spermidine and spermine were able to delay the oxidation at every step of the process, being as protective as octyl galate and more so than a-tocopherol and palmitoyl ascorbate. Finally, the antioxidant activity of polyamines was studied in extreme oxidation conditions of high temperature, oxygen and the addition of Fe2+ and was found to be related to their ability to chelate metals. (C) 2012 Elsevier Ltd. All rights reserved.