Active films based on cocoa extract with antioxidant, antimicrobial and biological applications.

Novel films of ethylene-vinyl alcohol copolymer (EVOH) containing flavonoid-rich cocoa were developed. To understand their potential application as active packaging material, antioxidant and antimicrobial properties of the films were determined as well as the antioxidant activity of the release compounds in Caco-2 human epithelial colorectal adenocarcinoma cells. Exposure of the films to aqueous food simulant showed antioxidant capacity. The release of cocoa extract components was dependent on the antioxidant concentration incorporated in the film and on temperature. Cocoa extract and the fraction obtained after in vitro gastrointestinal digestion presented antioxidant activity against oxidative stress induced by hydrogen peroxide in Caco-2 cells. Films with 10%, 15%, and 20% cocoa extract produced bactericidal effect against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salmonella enterica. The application of films to an infant milk formula, previously inoculated with L. monocytogenes, inhibited the growth of bacteria 1.5 log units the first day and showed sustained release, inhibiting 0.52 and 0.76 log units, respectively, by the sixth day, while cocoa powder added directly did not produce any effect.

Selective "one-pot" synthesis of functionalized cyclopentenones.

Double addition (1,2-1,4) of vinyl magnesium bromide to squaric acid derivatives allows the preparation of polyoxygenated cyclopentenones (8) in a "one-pot" procedure. The reaction occurs through the intermediate formation of octatetraenes (6). Protonation of this latter intermediate at -78 °C with TFE occurs selectively at the vinyl CH(2) closer to the metallic centers. DFT studies of the cyclization step justify the observed diastereoselectivity.