Isolation of [4-O-4]-linked biflavanoids from Acacia melanoxylon: first examples of a new class of single ether-linked proanthocyanidin dimers

Abstract

The isolation of the unique [4-0-4]-linked biflavanoids, [4-O-4]-bis(2,3-cis-3,4-trans-3,3′,4′,7,8-pentahydroxyflavan)(5) and the isomeric 2,3-cis-3,4-trans-3,3′,4′,7,8-pentahydroxyflavan-[4-O-4]-2,3-cis-3,4-cis-3,3,4′,7,8-pentahydroxyflavan (6), from the heartwood of Acacia melanoxylon further extends the heterogeneity of the interflavanoid linkage among natural proanthocyanidin dimers and oligomers.