2014 年 63 巻 8 号 p. 687-692
Polyphenols are widely distributed in plant foods, and are responsible for their taste, color, and health benefits. They have been proposed to play a key role in food stability and functions, owing to their ability to self-associate in a nonspecific way and to form colloids-like complexes. Although this behavior was characterized by some molecular analysis, such as NMR spectroscopy and molecular dynamics simulations, the detection of self-associated polyphenols has been difficult due to their instability and complexity. In the present study, we used catechin extract from tea as model polyphenols, and developed a new method for the detection of the self-association of tea polyphenols using native-polyacrylamide gel electrophoresis (native-PAGE). For the detection of the self-association, tea polyphenols were analyzed by native-PAGE/transblotting, followed by redox-cycling staining. The result showed that tea polyphenols were separated into the high-molecular weight region on the gel. In addition, both coomassie brilliant blue and silver staining, the general staining procedures to protein, were applicable to the analysis on the gel without transblotting. Furthermore, the association-dissociation behavior of tea polyphenols was characterized by using both the surfactant and the purified tea catechins. These results indicate that the band detected in the high-molecular weight region involves stable self-associated polyphenols. The detection and characterization of self-associated polyphenols are the important steps to evaluate the quality and functionality of foods including plant polyphenols. In the future, this method must be validated for more general purposes.