Condensed tannins. 5. The oxidative condensation of (+)-catechin
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منابع مشابه
Regioselective Synthesis of Procyanidin B6, A 4-6-Condensed (+)-Catechin Dimer, by Intramolecular Condensation.
Proanthocyanidins, also known as condensed tannins or oligomeric flavonoids, are found in many edible plants and exhibit interesting biological activities. Herein, we report a new, simple method for the stereoselective synthesis of procyanidin B6, a (+)-catechin-(4-6)-(+)-catechin dimer, by Lewis acid-catalyzed intramolecular condensation. The 5-O-t-butyldimethylsilyl (TBDMS) group of 5,7,3'4'-...
متن کاملCondensed tannins. 20. Chromophoric properties of flavan-4-ols, flavan-3,4-diols and condensed tannins.
Brown, B. R. & MacBride, J. A. H. (1963). Chem. & Ind. p. 1037. Clark-Lewis, J. W. & Jackman, L. M. (1961). Proc. chem. Soc. p. 165. Clark-Lewis, J. W., Jackman, L. M. & Williams, L. R. (1962). J. chem. Soc. p. 3858. Clark-Lewis, J. W. & Katekar, G. F. (1962). J. chem. Soc. p. 4502. Clark-Lewis, J. W. & Mortimer, P. I. (1960). J. chem. Soc. p. 4106. Conroy, H. (1960). Advanc. org. Chem. 2, 308....
متن کاملCONDENSED TANNINS: THE FORMATION OF A DIARYLPROP ANOL-CATECHINIC ACm DIMER FROM BASE-CATALYZED REACTIONS OF (+ )-CATECHIN
Reaction of (+ )-catechin at pH 12 and 40 DC results in the stereoselective (if not stereospecific) formation of an enolic form of 1-[6-(3',4'-dihydroxyphenyl)7 -hydroxybicyclo[3.3.1 Jnonane-2,4,9-trione-3-ylJ -1-(3,4-dihyroxyphenyl )-3-(2,4,6-trihydroxyphenyl)-propan-2-ol. The n.m.r. chemical shift assignments determined by a variety of two-dimensional experiments permit a conclusion that the ...
متن کاملIncreasing the oxidative stress response allows Escherichia coli to overcome inhibitory effects of condensed tannins.
Tannins are plant-derived polyphenols with antimicrobial effects. The mechanism of tannin toxicity towards Escherichia coli was determined by using an extract from Acacia mearnsii (Black wattle) as a source of condensed tannins (proanthocyanidins). E. coli growth was inhibited by tannins only when tannins were exposed to oxygen. Tannins auto-oxidize, and substantial hydrogen peroxide was genera...
متن کاملInteractions of Condensed Tannins with Selected Proteins
The relative affinities ufeondensed tannins purilied from sorghum, pinto bean, quebracho and wattle for six dissimilar protins have been determined by a competitive binding assay. The results indicate that tannin/protein interactions may be specific for different tanains as well as for different proteins. The highly specific interactions suggest that the differences in affinity are functionally...
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ژورنال
عنوان ژورنال: Biochemical Journal
سال: 1960
ISSN: 0306-3283
DOI: 10.1042/bj0760023