C-glycosidic ellagitannin metabolites in the heartwood of Japanese chestnut tree (Castanea crenata SIEB. et ZUCC.)

Abstract

HPLC comparison of tannins in the bark, sapwood and heartwood of Castanea crenata showed striking differences of composition. The major tannin of the bark is hamamelitannin, whereas vescalagin and castalagin are dominant in the wood. Inner heartwood contained three new C-glycosidic ellagitannin metabolites, castacrenins A, B and C. Outer heartwood contained dimeric, trimeric (castaneanin A), tetrameric (castaneanins B and C) and pentameric (castaneanin D) C-glycosidic ellagitannins composed of vescalagin and castalagin units. Castacrenins and castaneanins are derived from vescalagin and castalagin by intramolecular and intermolecular dehydration, respectively.