Base‐Catalyzed Reactions of Procyanidin B3: Formation of a Novel Catechinic Acid‐Catechin Dimer.

Reaction of procyanidin B3 (catechin‐(4α‐8)‐catechin) at pH 12 and 40°C gave a novel doubly‐linked catechinic acid‐catechin dimer, catechinic acid‐(8β‐8, 9‐ O ‐7)‐catechin, together with catechinic acid and a catechinic acid stereoisomer. The novel dimer had an unexpected β‐interunit linkage, which is contrary to the α‐interflavanoid bond of procyanidin B3, indicating that this compound was formed through the cleavage and recombination of the interflavanoid bond. The nature of the reaction products suggests that cleavage of both the interflavanoid bond and the pyran ring occurred and that the interflavanoid bond cleaved prior to the pyran ring. [ABSTRACT FROM AUTHOR]