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)-eniafzelechin-(4α→8)-epiafzelechin(8), epicatechin-(4β→8, 2β→O→7)-epiafzelechin-(4α→8)-epiafzelechin(9), epiafzelechin-(4β→8, 2β→O→7)-epizfzelechin-(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→β→7)-epicatechin-(4α→8)-epicatechin (15).