Über Catechin‐Dimere der Eichenrinde

Abstract

In der Eichenrinde wurde durch Massenspektrometrie Catechin-Catechin-6',8-Dimer gefunden, das mit dem durch Polyphenoloxidaseeinwirkung in vitro erhaltenen Catechin-Catechin-Dimer in der Fragmentierung iibereinstimmt. AuBerdem lie13 sich Gallocatechin-Catechin-6',8-Dimer durch Massenspektrometrie nachweisen; Catechin-Gallocatechin-6',8-Dimer, Leukodelphinidin-Catechin-4,8-Dimer und Leukodelphinidin-Gallocatechin-4,8-Dimer konnen vermutet werden. Catechin-dimers Contained in Oak BarkCatechin-catechin-6',8-dimer has been found in oak bark by masspectrometry which is identical in fragmentation with catechin-catechindimer product being recovered in vitro by the polyphenoloxidase process. The presence of gallocatechin-catechin-6',8-dimer has also been proven by masspectrometry; furthermore the presence of catechin-gallocatechin-6',8-dimer, leucodelphinidin-catechin-4,8dimer and leucodelphinidin-gallocatechin-4,8dimer can be assumed to be most likely.Bisher gelang es, drei Gruppen von kondensierten Gerbstoff-Dimeren zu erkennen: 1. Catechin-Dimere, die unter Saurekondensation in vitro aus (+)-Catechinl), aus Blockgabmir2) (Uncaria Garnbir) und aus dem Babulbaurn3) (Acacia arabica) gewonnen wurden, 2. Pro-anthocyanidin-Diere, die z.B. aus Kakaobohnen, Wejl3dornfriichten, Avocado-Samen u.a. isoliert wurden und durch Saurehydrolyse je ein Molekiil Catechin und Anthocyanidin lieferten4), 3. Catechin-Dimere, die aus (+)-Cate-K. Freudenberg und I. M. Alanso, Liebigs Ann. In dieser letzten Arbeit wurden die gegensatzlichen Ansichten der saurekatalysierten Selbstkondensation des (+)-Catechins geklart. Diese Klarung war aber bereits, wenn auch auf anderem Wege, K. Freudenberg und K. Weinges gelungen gewesen, woriiber berichtet wird in ,,Fortschritte der Chemie organischer Naturstoffe" K.

Bioassay-Guided Fractionation of a Leaf Extract from Combretum mucronatum with Anthelmintic Activity: Oligomeric Procyanidins as the Active Principle

“…Nevertheless, we could not determine the exact position of the linkage in ring D directly from the spectroscopic data obtained, but concluded from comparison to literature that the two rings are linked via position 6′ and 8. This compound or similar derivatives consisting of two catechin units have been synthesized enzymatically [26,27] and non-enzymatically [28,29] and have been also isolated from grape pomace [30] and oak bark [31].…”

Proanthocyanidins from the Bark ofHamamelis virginianaExhibit Antimutagenic Properties against Nitroaromatic Compounds

“…Although many fruits and vegetables accumulate proanthocyanidins, medicinal plant organs often contain higher amounts and are possibly more suitable for a protective effect. In the bark of Quercus robur the total amount of tannins is very high (more than 10%) (20) and a considerable part belongs to the mixed catechin and gallocatechin type (21).…”

Fortschritte der Chemie organischer Naturstoffe / Progress in the Chemistry of Organic Natural Products

“…From oak bark (Quercus robur, Fagaceae), different catechin dimers (677)(678)(679) have been isolated. From oak bark (Quercus robur, Fagaceae), different catechin dimers (677)(678)(679) have been isolated.…”