Figure 1.
Brewing epimerizes EGCG to GCG. The structures of additional epimerized green tea catechins (GC, CG, and C) formed during brewing are shown. The bond (shown in red) that changes orientation during brewing bridges the B- and C-rings. The three hydroxyl groups on the B-ring that are essential for activity as a covalent topoisomerase II poison are highlighted in blue.