New polymers from natural phenols using horseradish or soybean peroxidase

Full paper: The flavonol quercetin, its glycoside rutin, the flavanol catechin, the isoflavone daidzein and 5,6,4'-trihydroxyisoflavone can be oxidatively polymerized via a polyrecombination mechanism catalyzed by horseradish or soybean peroxidase in a mixture of phosphate buffer (pH 7) and 1,4-dioxane. The average molecular weights of the polymers were found to be in the range 4000-12000 g/mol. Daidzein derivatives with a methoxy (formononetin) or nitro group or a hydrogen atom at C-4' could not be polymerized under these conditions. These results and molecular modeling studies suggest that polymerisation preferentially occurs via the electron-rich ring B of the isoflavonoids. The polymers were characterized by means of FT-IR and UV spectroscopy, and their redox behavior was analyzed using cyclic voltammetry. Graphical presentation of the HOMO coefficients of daidzein (3a), calculated using the semiempirical AMI method, implemented in SPARTAN Pro 5.0.