‘Biting effect’ stabilizing gallate-type catechin/quaternary ammonium ion complexes

The relationship between the structure of catechins and their binding ability for quaternary ammonium ions was examined. From binding studies using eight catechins and benzyltrimethylammonium chloride, it was revealed that the binding ability of the gallate-type catechins is much higher than that of the non-gallate-type catechins. The quaternary ammonium ion binding site of the gallate-type catechins was determined to be the space formed by the galloyl group and the B-ring. The excellent binding ability of the gallate-type catechins is attributed to the ‘biting effect’ by the galloyl group and the B-ring.