Flavan-3-ols and procyanidins from the bark of Salix purpurea L |
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Authors: | Jürgenliemk G Petereit F Nahrstedt A |
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Institution: | Institute of Pharmaceutical Biology and Phytochemistry, Westf?lische Wilhems-University, Münster, Germany. |
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Abstract: | From a commercial aqueous ethanolic extract obtained from the bark of Salix purpurea L. the flavan-3-ols catechin, epicatechin, gallocatechin, catechin-3-O-(1-hydroxy-6-oxo-2-cyclohexene-1-carboxylic acid)-ester, the dimeric procyanidins B1, B3 and the trimeric procyanidins epicatechin-(4B-->8)-catechin-(4alpha-->8)-catechin and epicatechin-(4beta-->8)-epicatechin-(4beta-->8)-catechin were isolated. Structure elucidation was performed by NMR, CD, MS, degradation and optical rotation methods. A fraction containing higher oligomeric procyanidins was investigated by 13C NMR. Data indicate an average degree of oligomerization of 4 to 5 flavan-3-ol units with dihydroxylated B-rings and predominance of 2,3-cis-stereochemistry. |
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