Effects of Molecular Structure of Polyphenols on Their Noncovalent Interactions with Oat β-glucan

Few data were available on the interactions between polyphenols and polysaccharides. The effects of the chemical structure of polyphenols on their interactions with oat beta-glucan were analyzed. Ultrafiltration was applied to determine the adsorption capacities of polyphenols into oat beta-glucan. Hydroxylation favored the adsorption of flavonoids with three or fewer hydroxyl groups but deteriorated those with four or more hydroxyl groups. Among flavonoid isomers, the adsorption capacities increased in the order flavonol > flvaone > flavanone > isoflavone. Glycosylation exerted complicated influences on the adsorption capacities of flavonoids into oat beta-glucan. In most cases, methylation and methoxylation of phenolic acids lowered their adsorption capacities into oat beta-glucan. Esterification of gallic acid weakened its adsorption capacity into oat beta-glucan, whereas o-coumaric acid presented higher adsorption capacity into oat beta-glucan than p- and m-coumaric acids. Galloylation improved the adsorption capacities of catechins into oat beta-glucan.