Tannins and Related Compounds: XCI: Isolation and Characterization of Proanthocyanidins with an Intramolecularly Doubly-Linked Unit from the Fern, Dicranopteris pedata HOUTT

Abstract

A chemical examination of the polyphenolic constituents of the fern, Dicranopteris pedata Houtt., has led to the isolation of eight new proanthocyanidins possessing a doubly-linked (A-type) unit, together with known flavan-3-ols and proanthocyanidins. On the basis of chemical and spectroscopic evidence, they are characterized as epiafzelechin-(4β→8,2β-O-→ 7)-epiafzelechin-(4α→8)-epiafzelechin (8), epicatechin-(4β→8, 2β→O→7)-epiafzelechin-(4α→8)-epiafzelechin (9), epiafzelechin-(4β→8, 2β→O→7)-epiafzelechin-(4α→8)-epicatechin (10), epiafzelechin-(4β→8, 2β→O→7)-epicatechin-(4α→8)-epicatechin (11), epicatechin-(4β→8, 2β→O→7)-epiafzelechin-(4α→8)-epicatechin (12), epicatechin-(4β→8, 2β→O→7)-epicatechin-(4α→8)-epiafzelechin (13), epicatechin-(4β→8, 2β→O→7)-epicatechin-(4α→8)-epigallocatechin (14) and epiafzelechin-(4β→8)-epicatechin-(4β→8, 2β→O→7)-epicatechin-(4α→8)-epicatechin (15). © 1990, The Pharmaceutical Society of Japan. All rights reserved.