ISSN:
1750-3841
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
A study was conducted on the acetone- and ethyl-acetate-extractable flavan polyphenols of Waldhöfler apples, an astringent-tasting juice variety. The extracts were examined by cellulose thin-layer chromatography with 5% n-butanol and n-butanol—acetic acid—water (BAW) as the developing solvents. (—) Epicatechin was the major monomeric flavan found; (+) catechin was present in smaller amounts. A large number of unknown flavans were also detected; most of these are thought to be dimerie or oligomeric in composition, since their RI values did not correspond to those of any known flavans. The predominating unknown substance, R1 0.58 in 5% n-butanol and 0.46 in BAW, was purified from ethyl acetate extracts by polyamide chromatography followed by solvent fractionation. The pure compound had a marked astringent taste. The IR and UV spectra were typical of flavans. On hydrolysis, cyanidin and epicatechin were produced. Methylation with diazomethane yielded a compound with the empirical formula C3sH42O12H2O with a methoxyl content of 33.7%. NMR spectra indicated that condensations involved the A ring. Hydrolysis of the methylated derivative yielded tetramethyl epicatechin and a substance corresponding to tetramethyl flavan-3,4-diol and other unidentified intermediate products. It is thought that the purified proanthocyanidin is a dimer, or possibly an oligomer, containing (-) epicatechin and 5,7,3′,4′-flavan-3,4-diol as constituents.The other unknown flavans, not isolated in pure form, yielded cyanidin, (—) epicatechin, and a small amount of pelargonidin on hydrolysis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2621.1966.tb03277.x
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