Uso versátil de novos complexos de Mg(II): proteção a ERO’s à oxidação lipídica

Abstract

The search for compounds that have antioxidant properties is increasing due to their application in strategic areas such as food preservation, food supplements, active compounds in smart packaging, among others. This research work aims to prepare and characterize metallic Mg(II) complex containing in the coordination sphere ferulic acid (fer) and 1,10-phenanthroline (phen; Mg-phen-fer) and their application in polymeric films. The complex was characterized by infrared, electron injection mass spectrometry (MS-ESI) and 1H nuclear magnetic resonance and DOSY-NMR. The cyclic voltammograms obtained in aqueous solution in the anodic region showed a cyclic process indicating the stability of the species generated during the oxidation of coordinated ferulic acid, probably due to the stabilization of the corresponding phenoxyl radical via complexation with Mg(II), which is interesting for antioxidant applications. The Mg-phen-fer complex against the DPPH• radical presented an IC50 of 26 µM while for the BHT it was 40.9 µM. The same behavior is observed for the complex ABTS•+ radical presented an IC50 of 6 µM while for the BHT it was 16.75 µM. The complex showed total inhibition of 1O2 generation, at a concentration of 1.65 µg/mL. Furthermore, the complex was also able to stabilize riboflavin from the decomposition that occurs in the presence of light in an inert atmosphere. Regarding the peroxyl radicals that serve as a model for lipid radicals, the complex inhibited the generation of these radicals, presenting IC50 of 5µg/mL. In this work, two biopolymers were investigated for making the packaging material, tapioca starch and gelatin. It was found that the films containing the complex do not favor the proliferation of microorganisms, are always transparent, and are stable at temperatures of 30 °C and 40 °C observed in attenuated total reflection infrared (IR-ATR) measurements. The oxygen transmission capacity in the films was altered with the incorporation of the complex, with starch films being more susceptible to oxygen diffusion than gelatin films. The release of the complex from the two matrices was quick for systems with a high percentage of water. From the starch film, the total release in water took place in 30 minutes, in the presence of 50 % ethanol this release takes place in 200 minutes and in alcoholic systems only 10 % of the mass of the complex was released in more than three days. For the gelatin film, regardless of the aqueous media, release occurred within 60 min. With microbiology studies, for the Mg-phen-fer complex, it was verified that the minimum bactericidal concentration is 1.0 mg/mL and the minimum fungicidal concentration is 0.05 mg/mL. This complex stands out in food protection both for being a great candidate for antioxidant and for having an excellent antimicrobial activity. The complex has a high potential for application, and studies with different polymeric matrices must be carried out to delay controlled release, attracting a greater market value to the product.