Barricyclin D1—a dimeric ellagitannin with a macrocyclic structure—and accompanying tannins from Barringtonia racemosa

Abstract

ABSTRACT Our examination of high molecular weight polyphenolic constituents in the leaves of Barringtonia racemosa of the family Lecythidaceae uncovered 5 previously undescribed ellagitannins. One, barringtin M1 (1), among them was a hydrolysable tannin monomer, while remaining 4, barringtins D1 (2), D2 (3), D3 (4), and barricyclin D1 (5), were all dimers. Barricyclin D1 had a first macrocyclic structure formed from casuarictin (6) and tellimagrandin I (7), and the other ellagitannins had structures related to 5. Two additional known phenolics, valoneic acid dilactone (8) and schimawalin A (9), were also isolated from the leaves. These results suggested that the leaves of B. racemosa are a natural resource rich in hydrolysable tannin oligomers.