Flavan-3-ols and procyanidins from the bark of Salix purpurea

A. Nahrstedt; G. Jürgenliemk; F. Petereit

doi:10.1055/s-2006-950072

Planta Medica, Inhaltsverzeichnis

Flavan-3-ols and procyanidins from the bark of Salix purpurea

A Nahrstedt ², G Jürgenliemk ¹, F Petereit ²

¹Institute of Pharmaceutical Biology, Universitätsstr. 31, D-93053 Regensburg, Germany
²Institute of Pharmaceutical Biology and Phytochemistry, Hittorfstr. 56, D-48149 Münster, Germany

Abstract

From a hydroethanolic extract obtained from the bark of Salix purpurea L. (Salicaceae) the flavan-3-ols catechin, epicatechin, gallocatechin, catechin-3-O-(1-hydroxy-6-oxo-2-cyclohexene-1-carboxylic acid)-ester [1], the dimeric procyanidins B1, B3 [2] and the trimeric procyanidins epicatechin-(4ß8)-catechin-(48)-catechin [3] and epicatechin-(4ß8)-epicatechin-(4ß8)-catechin [4] were isolated. Their structures were elucidated by 1H-, 13C-NMR inlcuding COSY, HSCQ and HMBC methods and CD. The 13C-NMR spectral data of a fraction containing higher oligomeric procyanidins indicate an average degree of oligomerization of 4 to 5 flavan-3-ol units with dihydroxylated B-rings and predominance of the relative 2,3-cis-stereochemistry; B-ring trihydroxylated units were not detected.

Acknowledgements: Bionorica AG, Neumarkt (Germany), for financial support and the extract material.

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