Salix daphnoides: A Screening for Oligomeric and Polymeric Proanthocyanidins

Molecules

Stefan Wiesneth¹  Frank Petereit²  Guido Jürgenliemk¹ 

[1] Institute of Pharmaceutical Biology, Universitätsstr. 31, Regensburg D-93053, Germany; E-Mail:;Institute of Pharmaceutical Biology and Phytochemistry (IPBP), Corrensstr. 48, Münster D-48149, Germany; E-Mail:

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

DOI  :  10.3390/molecules200813764

来源: mdpi

【 摘 要 】

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 R_F-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.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.