Über Catechine und Ihre Herstellung Aus Leuko‐Anthocyanidin‐Hydraten

Weinges, Klaus

doi:10.1002/jlac.19586150124

Cited by 35 publications

(5 citation statements)

References 18 publications

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“…The gradational sequence of oligomeric phenolic units of increasing mass, comprising more than 70% of black wattle bark extract, is populated exclusively at triflavanoid level by prorobinetinidins (1 3a)-( 17a), whereas both profisetinidins [( 9), (lo)] and predominant prorobinetinidins [(l l), (12)] constitute the associated bifla~anoids.~ The overall excess of prorobinetinidins in the extract apparently correlates with the more rapid rate of formation of bi-and tri-flavanoid prorobinetinidins than their profisetinidin analogues during biomimetic-type condensations.…”

Section: [(13a) (15a)]2"r3"s4"r-2'r3's-2r3s4s [( 14a) (16a)l and 2"r3...mentioning

confidence: 99%

“…* Amongst the simple flavonoids which collectively represent a relatively low percentage of the phenolic fraction, three flavan-3-ols, namely (+ )-catechin (l), (+)-gallocatechin (2), and (-)-robinetinidol (4), predominate, while the flavan-3,4diols (+ )-leucofisetinidin (5) and (+)-leucorobinetinidin (6) occur at low concentration^.^ The pair of phloroglucinol-type flavan-3-01s ( + )-catechin and (+)-gallocatechin, as strongly nucleophilic substrates, and the aforementioned flavan-3,4diols as potential electrophiles, represent likely participants in electrophilic substitution reactions as judged from biomimetictype condensation^.^^^ The remaining flavonoids, mainly analogues of fisetinidin (7) and robinetinidin (8), all possess a 4-carbonyl function which not only precludes condensation at this point, but also deactivates their respective resorcinol A-rings towards electrophilic attack. Such selectivity in condensation is reflected by the isolation 495 of four [4,8]linked biflavanoids, namely 2,3-trans-3,4-trans:-and 2,3trans-3,4-cis:2',3'-trans-( -)-fisetinidol-( +)-catahin ( 9) and (10) and 2,3-trans-3,4-trans :2',3'-truns-( -)-robinetinidol-( + )catechin (1 1) and 2,3-trans-3,4-trans :2',3'-trans-( -)-robinetinidol-( +)-gallocatechin (12).$…”

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confidence: 99%

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Synthesis of condensed tannins. Part 7. Angular [4,6 : 4,8]-prorobinetinidin triflavanoids from black wattle (‘Mimosa’) bark extract

Viviers¹,

Botha²,

Ferreira³

et al. 1983

J. Chem. Soc., Perkin Trans. 1

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The triflavanoid fraction from the bark extract of the black wattle (Acacia mearnsii) comprises five angular prorobinetinidins with their constituent robinetinidol units [4,6 : 4,8] -linked to both (+)-catechin and (+) -gallocatechin. Synthetic proof of structure is provided for three bi-[ (-)-robinetinidol] -(+) -catechin diastereoisomers. The complete dominance of prorobinetinidins in the higher oligomeric fractions correlates with the faster condensation rate of the parent (+) -1eucorobinetinidin with the nucleophilic substrates compared with competing (+) -1eucofisetinidin.S 7 Part 6 is P.

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Section: [(13a) (15a)]2"r3"s4"r-2'r3's-2r3s4s [( 14a) (16a)l and 2"r3...mentioning

confidence: 99%

mentioning

confidence: 99%

Synthesis of condensed tannins. Part 7. Angular [4,6 : 4,8]-prorobinetinidin triflavanoids from black wattle (‘Mimosa’) bark extract

Viviers¹,

Botha²,

Ferreira³

et al. 1983

J. Chem. Soc., Perkin Trans. 1

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“…(+)-2,3-trans-3,4-trans-leucofisetinidin (4) of known absolute configuration (2R:3S:4R) with phloroglucinol or resorcinol at low acidity (0.1 M HC1) and ambient temperatures (-'20°C) proceeds rapidly (2-4 h) and stereoselectively,3'17 producing 3,4-trans-and 3,4-cis-4-arylflavan-3-ols (13,14) in the proportions of ca. 1.5-2:1.…”

Section: Hqç9ohmentioning

confidence: 99%

Structure and function in the biomimetic synthesis of linear, angular and branched condensed tannins

Roux¹,

Ferreira²

1982

Pure and Applied Chemistry

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The course and rate of direct biomimetic condensations of flavan-3,4-diois, as potential electrophiles, with progressively complex nucleophilic flavanoids to form oligomeric tannins is generally regulated by the functionality and hence stability of the parent carbocation generated under mild acid conditions; by the stereochemistry of the electrophile; by the relative nucleophilicity of competing centres on the complex substrates; by steric effects contributed by both the functionality and the stereochemistry of the nucleophile; by contributory hyperconjugative effects in both electro-and nucleophiles; and by stoichiometric considerations.Analogies available from analysis of natural sources indicate that the same precepts are obeyed during tannin biogenesis.Syntheses based on parent flavanoids of known absolute configuration, coupled with ultra high resolution 1H n.m.r. spectroscopy for determining relative configurations and condensation sequence of f lavanoid units in the resultant tannins, supported by circular dichroism, enable definition of their structures and absolute configurations.Condensed tannins are probably the most ubiquitous of all plant phenolics, and their exceptional concentrations in the barks and heartwoods of a variety of tree species, e.g. Acacia mearnsii (black wattle), Schinopsis spp. (quebracho) and Rhizophora spp. (mangrove) have resulted in their commercial extraction with the initial objective of applying the extracts in leather manufacture.In most instances this has led to the exploitation of indigenous forests (quebracho, mangrove), but the wattle bark industry in South Africa and also elsewhere, is uniquely based on sustained af forestation.Due to a slow but progressive world-wide decline in the use of vegetable extracts as tanning materials, the range of industrial applications of wattle ('Mimosa') extract has been extended through sustained local development to flocculants for water treatment; to depressants in ore flotation; to a variety of cold and thermosetting adhesives for manufacturing composite wood products; and to adhesives designed for the packaging industry.1 These established industrial uses are based on the 70% phenolic ('tannin') content of the natural extract, representing a molecular gradation over the mass range 300-3000 and with a number average mass approximating to 1250.2 Knowledge of tannin structure and extract composition has contributed significantly to some of these developments.The chemistry of those condensed tannins which are of commercial significance, and also of others of more academic 'interest, has until of late represented an unattractive and therefore much neglected area of research.Inhibiting factors have been the extreme complexity of tannin extract composition; the high chirality of the constituent oligomers; their relative sensitivity towards stereochemical inversion; and susceptibility to autoxidation.Our dissatisfaction with the obvious limitations of chemical and spectrometric analysis prompted an exploration into methods of direct synthesi...

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“…From 80% aqueous methanol extract of the roots of S. yunnanensis, we isolated a new flavonoid, named sophorayunnanol (1), together with eight known polyphenols, such as dihydrorobinetin (2), 6,7) sepinol (3), 8) robtin (4), [9][10][11] robinetin (5), [12][13][14] 3,7,3Ј,5Ј-tetrahydroxy-4Ј-methoxyflavone (6), 15) laurentinol (7), 16) gliricidol (8), 8) and piceatannol (9) (Fig. 1).…”

mentioning

confidence: 99%

Polyphenols from Sophora yunnanensis, and Their Inhibitory Effects on Nitric Oxide Production

Daikonya

Kitanaka

2011

CHEMICAL & PHARMACEUTICAL BULLETIN

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A new flavonoid, (2R,3R)-3,7,4 -trihydroxy-3 ,5 -dimethoxyflavanone, named sophorayunnanol (1), together with eight known polyphenols (2-9), were isolated from the roots of Sophora yunnanensis C. Y. MA (Leguminosae). The structure including absolute stereochemistry of 1 was determined by spectroscopic (high resolution (HR)-MS, 1D-and 2D-NMR, and circular dichroism (CD)) methods. The inhibitory activity of these compounds was examined against nitric oxide (NO) production by lipopolysaccharide (LPS) and interferon (IFN)-g g activated macrophages, RAW264.7 cells. 3,7,3 ,5 -Tetrahydroxy-4 -methoxyflavone (6) and piceatannol (9) showed potent inhibitory activity against the production of NO with IC 50 values of 14.4؎ ؎2.5 and 12.9؎ ؎1.8 m mM, respectively. This article is the first report on phytochemical study of S. yunnanensis.

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Über Catechine und Ihre Herstellung Aus Leuko‐Anthocyanidin‐Hydraten

Cited by 35 publications

References 18 publications

Synthesis of condensed tannins. Part 7. Angular [4,6 : 4,8]-prorobinetinidin triflavanoids from black wattle (‘Mimosa’) bark extract

Synthesis of condensed tannins. Part 7. Angular [4,6 : 4,8]-prorobinetinidin triflavanoids from black wattle (‘Mimosa’) bark extract

Structure and function in the biomimetic synthesis of linear, angular and branched condensed tannins

Polyphenols from Sophora yunnanensis, and Their Inhibitory Effects on Nitric Oxide Production

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