Salix daphnoides: A Screening for Oligomeric and Polymeric ProanthocyanidinsReportar como inadecuado




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1

Institute of Pharmaceutical Biology, Universitätsstr. 31, Regensburg D-93053, Germany

2

Institute of Pharmaceutical Biology and Phytochemistry IPBP, Corrensstr. 48, Münster D-48149, Germany





*

Author to whom correspondence should be addressed.



Academic Editor: Thomas J. Schmidt

Abstract In the present study, a qualitative analysis of proanthocyanidins PAs from an aqueous-methanolic extract of Salix daphnoides VILL. bark is described. Procyanidin B1 1, B2 2, B3 3, B4 4, C1 5, epicatechin-4β→8-epicatechin-4β→8-catechin 6 and epicatechin-4β→8-epicatechin-4β→8-epicatechin-4β→8-catechin 7 have been isolated by a combination of different chromatographic separations on Sephadex® LH-20-, MCI®-, Diol-and RP-18-phases. Mass spectrometry, 1D- and 2D-NMR, circular dichroism and polarimetry were used for their structure elucidation and verification by comparison with the literature. Additionally, two fractions of very polar flavan-3-ols were compared: -regular- polymeric PAs received at the very end of the Sephadex® LH-20 chromatography showing no mobility on silica TLC and -unusual- PAs with the same RF-value but already eluting together with flavonoids in the Sephadex® LH-20 system. These -unusual- PAs were subsequently enriched by centrifugal partition chromatography CPC. 13C-NMR, polarimetry, thiolysis, acid hydrolysis and phloroglucinol degradation were used to characterize both fractions. Differences in the composition of different flavan-3-ol units and the middle chain length were observed. View Full-Text

Keywords: procyanidins; proanthocyanidins; flavan-3-ols; Salix daphnoides; willow bark; low temperature NMR; thiolysis; polarimetry; polymeric proanthocyanidins procyanidins; proanthocyanidins; flavan-3-ols; Salix daphnoides; willow bark; low temperature NMR; thiolysis; polarimetry; polymeric proanthocyanidins





Autor: Stefan Wiesneth 1, Frank Petereit 2 and Guido Jürgenliemk 1,*

Fuente: http://mdpi.com/



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