- Proanthocyanidins and a phloroglucinol derivative from Rumex acetosa L.
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From the ethyl acetate soluble fraction of an acetone-water extract of the aerial parts of Rumex acetosa L. (Polygonaceae), a variety of monomeric flavan-3-ols (catechin, epicatechin, epicatechin-3-O-gallate), A- and B-type procyanidins and propelargonidins (15 dimers, 7 trimers, 2 tetramers) were isolated with 5 so far unknown natural products. Dimers: procyanidin B1, B2, B3, B4, B5, B7, A2, epiafzelechin-(4β→8)-epicatechin, epiafzelechin-(4β→8)-epicatechin-3-O-gallate (new natural product), epiafzelechin-(4β→6)-epicatechin-3-O-gallate (new natural product), epiafzelechin-3-O-gallate-(4β→8)-epicatechin-3-O-gallate, B2-3′-O-gallate, B2-3,3′-di-O-gallate, B5-3′-O-gallate, and B5-3,3′-di-O-gallate. Trimers: procyanidin C1, epiafzelechin-(4β→8)-epicatechin-(4β→8)-epicatechin (new natural product), epicatechin-(4β→8)-epicatechin-(4β→8)-catechin, cinnamtannin B1, cinnamtannin B1-3-O-gallate (new natural product), tentatively epicatechin-(2β→7, 4β→8)-epiafzelechin-(4α→8)-epicatechin (new natural product), and epicatechin-3-O-gallate-(4β→8)-epicatechin-3-O-gallate-(4β→8)-epicatechin-3-O-gallate. Tetramers: procyanidin D1 and parameritannin A1. All compounds were elucidated by ESI-MS, CD spectra, 1D- and 2D-NMR experiments as free phenols or peracetylated derivatives and, in part, after partial acid-catalysed degradation with phloroglucinol. A more abundant proanthocyanidin polymer was also isolated, purified and its chemical composition studied by 13C NMR. In addition a so far unknown phloroglucinolglycoside (1-O-β-d-(2,4-dihydroxy-6-methoxyphenyl)-6-O-(4-hydroxy-3,5-dimethoxybenzoyl)-glucopyranoside) was isolated.
- Bicker,Petereit,Hensel
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experimental part
p. 483 - 495
(2010/06/15)
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- Synthesis of [4-14C]-pelargonidin chloride and [4- 14C]-delphinidin chloride
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The synthesis of [4-14C]-pelargonidin chloride and [4- 14C]-delphinidin chloride via [formyl-14C]-2-(benzoyloxy)- 4,6-dihydroxybenzaldehyde, ω,4-diacetoxyacetophenone and ω,3,4,5-tetraacetoxyacetophenone is described. The first step comprised labelling of the carbonyl group of 2-(benzoyloxy)-4,6-dihydroxybenzaldehyde, verifying that the coupling with ω,4-diacetoxyacetophenone or ω,3,4,5-tetraacetoxyacetophenone under hydrogen chloride atmosphere resulted in the formation of [4-14C] labelled anthocyanidins. Copyright
- Kraus, Michael,Biskup, Ellen,Richling, Elke,Schreier, Peter
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p. 1151 - 1162
(2007/10/03)
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