Experimental Development of Antioxidant Alginate Films

Bioactive films encapsulating antioxidant compounds are increasingly used in skin patches, mucoadhesive drug release systems, nutraceutical coatings and engineered tissue substitutes. However, the loading dosage incorporated into the film remains a highly empirical issue concerning the design of these devices, since there are no methods to determine optimal or effective antioxidant loads. In this work, alginate and epicatechin were selected as prototypical components in the development of bioactive-loaded materials for biomedical and food applications. After testing, a methodology is proposed to predict effective antioxidant dosages. Studies with the biopolymer showed that formation of calcium alginate pre-gel can be followed by simple turbidity measurements, and this matrix was used as model system to investigate epicatechin bioactivity in the presence of the polysaccharide. The antioxidant activities of different concentrations of the flavonoid were studied by two assays, the cytochrome c reduction in alginate pre-gel and the prevention of oil oxidation. The results converged to 100 ppm concentration as efficacious load of epicatechin to use. Alginate films loaded with this antioxidant dosage were tested in pine nuts and the films were able to slow down lipid oxidation, as indicated by peroxide value and conjugated dienes parameters. The experimental approach here presented may be useful to further systematize the design of multifunctional antioxidant systems with different applications.