Epimerization of Tea Catechins under Weakly Acidic and Alkaline Conditions

Abstract

Tea catechins in a buffer at pH 7 with N₂ replacing O₂ epimerized rapidly at 80 °C with less than 10% of oxidative side reactions and gave catechin epimers in a 50–63% yield. The epimerization of catechins with three hydroxyl groups was faster than with two groups, and of galloyl-free catechins was faster than catechins with a galloyl ester.