Electron Transfer within an Antioxidant Powder Composite with Layered Double Hydroxide Nanoparticles and Tomato Extract

Abstract

Antioxidants are demanded compounds in the polymer, cosmetics, food, and health industry. Preparation of composites with antioxidants and layered double hydroxides (LDH) is a strategy to optimize antioxidant function and facilitate its addition to commercial products; therefore, understanding the antioxidant behavior of new antioxidant composites is needed to define and design the applications. We report a composite formed by MgAl-NO3 layered double hydroxide nanoparticles spread along a lycopene matrix extracted from a tomato. Electron paramagnetic resonance (EPR) spectroscopy followed the reaction of hydroxyl radicals with the antioxidant composite material. The composite was reacted with different volumes of 30% H2O2 solution. Initially, the organic fraction of the composite reacts with OH· radicals and forms organic free radicals (OFR) detected with g = 2.009 in the EPR spectra. As the amount of OH·reacting with the composite increased, the intensity of OFR also increased; later, the unpaired electrons migrated to the MgAl-NO3 LDH nanoparticles, producing a new absorption signal with g = 2.020 in the EPR spectrum. This signal was assigned to the reduction of aluminum sites in the LDH. LDH particles are suitable components to increase the antioxidant performance composites produced with natural compounds.