61541-02-4Relevant academic research and scientific papers
Polyphenolic constituents of cynomorium songaricum Rupr. and antibacterial effect of polymeric proanthocyanidin on methicillin-resistant staphylococcus aureus
Jin, Shangwu,Eerdunbayaer,Doi, Airi,Kuroda, Teruo,Zhang, Guixia,Hatano, Tsutomu,Chen, Guilin
experimental part, p. 7297 - 7305 (2012/10/08)
Oligomeric and polymeric flavan-3-ols were obtained by chromatographic fractionation of extracts from Cynomorium songaricum Rupr. The structure of the polymeric constituent, cynomoriitannin, was characterized using spectral and chemical data. Results from acid-catalyzed degradation indicated that cynomoriitannin is a polymeric proanthocyanidin predominantly composed of epicatechin, together with low proportions of epicatechin-3-O-gallate and catechin as extension units. The terminal unit was chiefly composed of catechin, with an admixture of epicatechin. Size exclusion chromatographic analysis demonstrated a mean polymerization degree of 14. Two new phloroglucinol adducts (cynomoriitannin-phloroglucinol adducts A and B) obtained by acid-catalyzed degradation of cynomoriitannin in the presence of phloroglucinol were characterized using spectral analyses. Six oligomeric flavan-3-ols were also identified as follows: procyanidin B3, catechin-(6'-8)-catechin, catechin-(6′-6)-catechin, epicatechin-(4β-8)- epicatechin-(4β-8) -catechin, epicatechin-(4β-6)-epicatechin-(4β-8)-catechin, and arecatannin A1, respectively. These flavan-3-ols were isolated from C. songaricum. This is the first time that this procedure has been described. The antibacterial activity of the fractions and constituents was tested against methicillin-resistant Staphylococcus aureus (MRSA). The crude acetone-water (7:3) extract had moderate activity against MRSA. Cynomoriitannin was the most effective of the plant constituents against MRSA.
Isolation and structure elucidation of tetrameric procyanidins from unripe apples (Malus pumila cv. Fuji) by NMR spectroscopy
Nakashima, Shohei,Oda, Chihiro,Masuda, Susumu,Tagashira, Motoyuki,Kanda, Tomomasa
, p. 144 - 152 (2012/11/13)
Procyanidins are plant secondary metabolites widely consumed and known to have various physiological functions, but their bioavailability and mechanism of action are still unclear especially for larger oligomers. One of the reasons is scarce information about the detailed structure of oligomeric procyanidins. As for apple, structures of procyanidin components larger than trimers are scarcely known. In this study, 11 tetrameric procyanidins including two known compounds were isolated from unripe apples (Malus pumila cv. Fuji) and identified by NMR spectroscopic analysis and phloroglucinol degradation. As a result, the detailed structural diversity of tetrameric procyanidins in apple was established.
Synthesis and ribonuclease A inhibition activity of resorcinol and phloroglucinol derivatives of catechin and epicatechin: Importance of hydroxyl groups
Dutta, Sansa,Basak, Amit,Dasgupta, Swagata
experimental part, p. 6538 - 6546 (2010/10/03)
The reported ribonuclease A inhibitory activity of the green tea extracts prompted us to synthesize novel catechin/epicatechin based conjugates with resorcinol and phloroglucinol with the aim to increase the number of phenolic OH groups. These are found to be more effective inhibitors of ribonuclease A as compared to catechin and epicatechin thus indicating the importance of number of phenolic OH groups for the inhibition of ribonucleolytic activity. Fluorescence studies have been carried out to evaluate the binding parameters. The protein-ligand docking studies are also performed to gain insight into the protein-polyphenols interactions. The epicatechin based polyphenols 1 and 2 also showed inhibition of angiogenin-induced angiogenesis, as determined by chorioallantoic membrane (CAM) assay.
Synthesis and preliminary anticancer activity studies of C4 and C8-modified derivatives of catechin gallate (CG) and epicatechin gallate (ECG)
Hayes, Christopher J.,Whittaker, Benjamin P.,Watson, Susan A.,Grabowska, Anna M.
, p. 9701 - 9712 (2007/10/03)
We have developed an improved and reliable method for stereoselective functionalization at C4 of naturally occurring (+)-catechin. Our method utilizes DDQ oxidation followed by trapping of the quinonemethide intermediate with allyl alcohol. The quinonemethide intermediate can be regenerated from the allyl ether by exposure to boron trifluoride diethyl etherate. This reactive intermediate can be trapped with a wide range of external nucleophiles. NBS bromination, lithium halogen exchange, and alkylation gave access to C8-allyl derivatives of (+)-catechin, and this allyl group was used in a series of cross-metathesis experiments to prepare novel dimeric catechin-derived products. Gallate ester derivatives of the novel C4- and C8-substituted catechins were prepared, and these materials were screened for potential anticancer activity in a range of human cancer cell lines. From these preliminary cytotoxicity assays (MTT) we found that C8-propyl-catechin gallate was more active (IC50 = 31 μM) than catechin gallate (CG, IC50 = 53 μM) or epicatechin gallate (ECG, IC50 = 76 μM) against the colorectal adenocarcinoma cell line HCT116. Differential sensitivity in pancreas (Pan1), bladder (RT112), stomach (MGLVA1), liver (HepG2), and fibroblasts (46Br.1G1) cell lines was also observed.
Structural identification and distribution of proanthocyanidins in 13 different hops
Li, Hui-Jing,Deinzer, Max L.
, p. 4048 - 4056 (2007/10/03)
Ten newly isolated hop proanthocyanidin oligomers and flavan-3-ol monomers from 13 different hops have been identified as gallocatechin, gallocatechin-(4α→8)-catechin, gallocatechin-(4α→6)- catechin, catechin-(4α→8)-gallocatechin, catechin-(4α→6)- gallocatechin, afzelechin-(4α→8)-catechin, catechin-(4α→8) -catechin-(4α→8)-catechin, epicatechin-(4β→8)-epicatechin- (4β→8)-catechin, catechin-(4α→8)-gallocatechin- (4α→8)-catechin, and gallocatechin-(4α→8)-gallocatechin- (4α→8)-catechin, together with seven previously isolated oligomers, namely, catechin, epicatechin, epicatechin-(4β→8)-catechin, epicatechin-(4β→8)-epicatechin, catechin-(4α→8)-catechin, catechin-(4α→8)-epicatechin, and epicatechin-(4β→8)- catechin-(4α→8)-catechin. These compounds were subjected to acid-catalyzed degradation in the presence of phloroglucinol or by partial or complete acid-catalyzed degradation and reaction with benzyl mercaptan followed by desulfurization. The resultant adducts when compared to authentic samples by high-performance liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry and high-performance liquid chromatography-electrospray ionization tandem mass spectrometry served to identify the precursors. The composition of proanthocyanidins from 13 different hops was similar, but the concentration of individual compounds showed some differences, which indicated that hop proanthocyanidin profiles are affected by geographic origin and are variable depending on the cultivars.
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
Spectroscopic Properties of Free Phenolic 4-Arylflavan-3-ols as Models for Natural Condensed Tannins
Zyl, Pieter W. van,Steynberg, Jan P.,Brandt, Edward V.,Ferreira, Daneel
, p. 1057 - 1063 (2007/10/02)
A unique range of free phenolic 4-arylflavan-3-ols consisting of four sets (3',4',5,7-tertrahydroxyflavan-3-ol or its 5-deoxy analogue coupled to phloroglucinol or resorcinol), each composed of three diastereomers (2,3-trans-3,4-trans, 2,3-trans-3,4-cis and 2,3-cis-3,4-trans) were synthesized to assess their spectroscopic properties. 1H and 13C NMR and circular dichroism data are related to selected structural and stereochemical features with a view to modelling natural phenolic oligoflavanoids. - Key words: 4-Arylflavan-3-ols 1H NMR 13C NMR Circular dichroism Condensed tannins
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.
Condensed Tannins. Base-catalysed Reactions of Polymeric Procyanidins with Phloroglucinol: Intramolecular Rearrangements
Laks, Peter E.,Hemingway, Richard W.,Conner, Anthony H.
, p. 1875 - 1882 (2007/10/02)
Reactions of polymeric procyanidins with phloroglucinol at pH 12.0 and temperatures of 23 or 50 deg C gave epicatechin-(4β)-phloroglucinol (7), by cleveage of the interflavanoid bond between procyanidin units with subsequent addition of phloroglucinol, and (+)-catechin from the terminal unit.The phloroglucinol adduct (7) rearranged to an enolic form of 8-(3,4-dihydroxyphenyl)-7-hydroxy-6-(2,4,6-trihydroxyphenyl)bicyclononane-2,4,9-trione (9).Rearrangement of a dimeric procyanidin phloroglucinol adduct resulted in the formation of 3'-8-(3,4-dihydroxyphenyl)-7-hydroxy-2,4,9-trioxobicyclononan-6-yl>-4-(3,4-dihydroxyphenyl)-2',3,4',5,6',7-hexahydroxyflavan (10), also in an enolic form. (+)-Catechin, from the terminal unit, gave catechinic acid, a enolic form of 6-(3,4-dihydroxyphenyl)-7-hydroxybicyclononane-2,4,9-trione (4).
