79907-46-3Relevant academic research and scientific papers
Proanthocyanidins and a phloroglucinol derivative from Rumex acetosa L.
Bicker,Petereit,Hensel
experimental part, p. 483 - 495 (2010/06/15)
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.
Tannins and Related Compounds. I. Rhubarb (1)
Nonaka, Gen-Ichiro,Nishioka, Itsuo,Nagasawa, Tetsuro,Oura, Hikokichi
, p. 2862 - 2870 (2007/10/02)
Three new tannin-related compounds (I, II and III), along with lindleyin (IV), (+)-catechin, 3-O-galloyl-(-)-epicatechin, gallic acid, 3,5,4'-trihydroxystilbene 4'-O-β-D-(6''-O-galloyl)-glucopyranoside, 3,5,4'-trihydroxystilbene 4'-O-β-D-glucopyranoside and 4-(4'-hydroxyphenyl)-2-butanone 4'-O-β-D-glucopyranoside, have been isolated from commercial rhubarb (Rhei Rhizoma).On the basis of spectral and chemical evidence, I, II and III were characterized as 3,3'-di-O-galloylprocyanidin B-2, 3-O-galloylprocyanidin B-1 and 1,2,6-tri-O-galloylglucose, respectively.The occurence of IV in rhubarb is of great significance, since IV has been reported to have analgesic and anti-inflammatory activities almost equal to those of aspirin and phenylbutanone.Tannins in rhubarb have been partially purified (designated as rhatannin (V)).Thiolysis degradation and enzymatic hydrolysis have shown that V is mainly composed of C4 to C8 linked 3-O-galloyl-(-)-epicatechin units in the extension part (upper part) with either 3-O-galloyl-(-)-epicatechin or (+)-catechin unit in the lower terminal part.Keywords. rhubarb; polygonaceae; 3,3'-di-O-galloylprocyanidin B-2; 3-O-galloylprocyanidin B-1; 1,2,6-tri-O-galloylglucose; lindleyin; rhatannin
