37064-35-0Relevant academic research and scientific papers
Phenolics from Maytenus senegalensis
Hussein, Ghazi,Nakamura, Norio,Meselhy, Meselhy R.,Hattori, Masao
, p. 689 - 694 (1999)
Two new methylated flavan-3-ol glucosides and a methylated proanthocyanidin were isolated from the MeOH extract of the stem-bark of Maytenus senegalensis, together with five known compounds. The structures of the new compounds were determined as: (-)-4'-m
Studies on the constituents of bark of Parameria laevigata Moldenke
Kamiya,Watanabe,Endang,Umar,Satake
, p. 551 - 557 (2007/10/03)
One new trimeric proanthocyanidin, epicatechin-(2β→O→7,4β→6)-epicatechin- (2β→O→7, 4β→8)epicatechin (5) and two new tetrameric proanthocyanidins, epicatechin-(2β→O→7, 4β→8)-[epicatechin-(4β6)]epicatechin-(4β→8)- epicatechin, named as parameritannin A-1 (6), and epicatechin-(2β→O→5, 4β→6)[epicatechin-(2β→O→7, 4β→8)]-epicatechin-(4β→8)-epicatechin, named as parameritannin A-2 (7), have been isolated from the bark of Parameria laevigata Moldenke (Apocynaceae) along with the two known dimers, proanthocyanidin A-2 (1) and proanthocyanidin A-6 (2), and two dimers, cinnamtannin B-1 (3) and aesculitannin B (4). These structures were elucidated by spectral and chemical evidence.
Oligomeric flavanoids. Part 27. Interflavanyl bond formation in procyanidins under neutral conditions
Steynberg, Petrus J.,Nel, Reinier J.J.,Van Rensburg, Hendrik,Bezuidenhoudt, Barend C.B.,Ferreira, Daneel
, p. 8153 - 8158 (2007/10/03)
Dimethyl(methylthio)sulfonium tetrafluoroborate (DMTSF) and silver tetrafluoroborate (AgBF4) activate the C4-S bond in the 4-thioethers of flavan-3-ols toward carbon nucleophiles to permit formation of the interflavanyl bond in procyanidins under neutral conditions.
Proanthocyanidins from Lotus Corniculatus
Foo,Newman,Waghorn,Mcnabb,Ulyatt
, p. 617 - 624 (2007/10/03)
The chemical structure of the purified proanthocyanidin polymers of Lotus corniculatus was analysed by 13CNMR and by mild acid catalysed degradation in the presence of excess of phloroglucinol. The NMR data showed that the polymer was partially glycosidated with a number average Mr in the range 1800-2100 (six to seven flavanoid units). The products from phloroglucinol scission reaction indicated the extender flavan units to consist mostly of epicatechin (67%) and epigallocatechin (30%), with minor amounts of catechin and epiafzelechin units, which were linked together predominantly by C-4/C-8 interflavanoid bonds. The polymer chains were terminated mostly by catechin (83%) and, to a lesser extent, by epicatechin (16%). Copyright
PROANTHOCYANIDIN POLYMERS WITH ANTISECRETORY ACTIVITY AND PROANTHOCYANIDIN OLIGOMERS FROM GUAZUMA ULMIFOLIA BARK
Hoer, Michaela,Heinrich, Michael,Rimpler, Horst
, p. 109 - 120 (2007/10/03)
Bioassay-guided fractionation of a crude extract of Guazuma ulmifolia bark led to the isolation of polymeric proanthocyanidins which inactivated cholera toxin (CT).The average degree of polymerization (DP) of the active compounds ranged from 14.4 to 32.0.The polymers consisted mainly of (-)-epicatechin units.In polymers of a representative fraction, the flavanol units were connected by 8> bonds and, less frequently, by 6> bonds.Inhibition of CT by tannins increased with Mr and conformation flexibility of the tannin molecule.Several known procyanidin oligomers were also isolated. 1H NMR shift rules to distinguish between 8> and 6> linked proanthocyanidin peracetates, that have been proposed for dimers, were extended to trimers and a tetramer.A further diagnostic shift parameter to determine the interflavanoid bonding position is presented and the conformation of oligomeric proanthocyanidin peracetates is discussed. - Key Word Index: Guazuma ulmifolia; Sterculiaceae; bark; proanthocyanidins; tannins; polymers; gel permeation chromatography; NMR; thiolytic degradation; (-)-epicatechin; peracetates; antisecretory activity.
Tannins from Betel Nuts
Ma, Ying-Tsun,Hsu, Feng-Lin,Lan, Shu-Jan J.,Chen, Chieh-Fu
, p. 77 - 81 (2007/10/03)
From the acetone extract of fresh betel nuts, two procyanidin pentamers, two procyanidin tetramers and three procyanidin trimers, along with (+)-catechin, (-)-epicatechin, procyanidin A-1, procyanidin B-1, procyanidin B-2, and procyanidin B-7 were isolated. Based on 1H NMR and 13C NMR spectral data as well as the results of thiolysis degradation, the chemical structures of two series of oligomeric arecatannins A and B have been established. The arecatannins from betel nuts were found to be condensed-type tannins which possess (-)-epicatechin unit and (+)-catechin units. All arecatannins had C4-C8 linked (-)-epicatechin in the upper units whereas the (+)-catechin in the terminal unit had C4-C8 or C4-C6 linkage.
THIOLYSIS OF BIRCH BARK PROCYANIDINES: STRUCTURAL DEPENDENCE IN FORMATION OF 2,3-CIS-3,4-CIS-FLAVAN-4-BENZYLTHIOETHERS FROM PROCYANIDINS
Kolodziej, Herbert
, p. 1671 - 1674 (2007/10/02)
Thiolytic studies of the birch bark procyanidins, epicatechin-(4β->8)-catechin (B1), epicatechin-(4β->6)-catechin (B7) and epicatechin-(4β->8)-epicatechin-(4β->8)-catechin, provided, in addition to known β-thioethers, evidence for the presence of the first 2,3-cis-3,4-cis-flavan-4-benzylthioethers.Their formation is dependent on the 2,3-stereochemistry of the 'lower' terminal flavan unit and apparently on the relative lability of the interflavanoid linkage.By contrast, epicatechin-(4β->8)-epicatechin (B2), epicatechin-(4β->6)-epicatechin (B5) and epicatechin-(4β->8)-epicatechin-(4β->8)-epicatechin (C1), afforded only 2,3-cis-3,4-trans-flavan-4-benzylthioethers.
4-CARBOXYMETHYL FLAVAN-3-OLS AND PROCYANIDINS FROM DAVILLIA DIVARICATA
Hwang, Tieh-Horng,Kashiwada, Yoshiki,Nonaka, Gen-Ichiro,Nishioka, Itsuo
, p. 279 - 282 (2007/10/02)
A series of flavan-3-ols and procyanidins, processing a carboxymethyl group, and a procyanidin tetramer have been isolated from the fern, Davallia divaricata.The structures were characterized on the basis of chemical and spectral evidence.
PROCYANIDIN POLYMERS OF DOUGLAS FIR BARK: STRUCTURE FROM DEGRADATION WITH PHLOROGLUCINOL
Foo, Lai Yeap,Karchesy, Joseph J.
, p. 3185 - 3190 (2007/10/02)
Reaction of the condensed tannin polymers of Douglas fir inner bark with phloroglucinol yielded catechin, epicatechin, procyanidin B-2, catechin-(4α->2)-phloroglucinol, epicatechin-(4β->2)-phloroglucinol, the novel compound epicatechin-(4α->2)-phloroglucinol and 1,3-di-(2,4,6-trihydroxyphenyl)-1-(3,4-di-hydroxyphenyl)-propan-2-ol.Also isolated were epicatechin-(4β->8)-epicatechin-(4β->2)-phloroglucinol, epicatechin-(4β->6)-epicatechin-(4β->2)-phloroglucinol, and three other novel phloroglucinol adducts, catechin-(4α->8)-epicatechin-(4β->2)-phloroglucinol, epicatechin-(4β->8)-epicatechin-(4β->8)-epicatechin-(4β->2)-phloroglucinol and epicatechin-(4β->6)-epicatechin-(4β->8)-epicatechin-(4β->2)-phloroglucinol.The results suggest that the configuration of the extender units is almost exclusively 2,3-cis, while the terminal units are mixed, with 2,3-cis slightly predominating.The C-4 to C-8 interflavonoid linkage predominates over the C-4 to C-6 linkage by a 4:1 ratio. Key Word Index Pseudotsuga menziesii; Pinaceae; Douglas fir; procyanidin; degradation; phloroglucinol-adducts.
PROCYANIDIN DIMERS AND TRIMERS FROM DOUGLAS FIR INNER BARK
Foo, Lai Yeap,Karchesy, Joseph J.
, p. 1743 - 1748 (2007/10/02)
The aqueous fraction of the inner bark extract of Douglas fir (Pseudotsuga menziesii) yielded two novel natural procyanidin trimers, epicatechin-(4β->8)-catechin-(4α->8)-catechin and epicatechin-(4β->6)-epicatechin-(4β->8)-epicatechin, and two known trimers, epicatechin-(4β->8)-epicatechin-(4β->8)-epicatechin and epicatechin-(4β->8)-epicatechin-(4β->8)-catechin.Catechin, epicatechin and procyanidin dimers B1, B2, B3 and B4 were also isolated.The structures of all of these procyanidins were elucinated from their 13C NMR data and by partial acid catalysed degradation with benzylthiol.Key Word Index - Pseudotsuga mentiesii; Pinaceae; flavon-3-ols; procyanidin; dimers; trimers; benzylthiol; degradation.
