Kinetic study of the chemical behavior of quercetin and Kaempferol in alkaline media

In this work the kinetics of the oxidation of two flavonols in alkaline medium have been studied. The fluorescence of quercetin and kaempferol has been monitored by a fluorimetric technique after the addition of an alkaline buffer to their alcoholic solutions. The pH, at which the rate of their fluorescence decrease has its maximum, was 11.0. The oxidation of the two flavonols in alkaline medium follows a first order kinetic. The reaction rate constants of this reaction are 27.5×10-3 sec-1 and 1.22×10-3 sec-1 for quercetin and kaempferol respectively. Working curves in the range of 2.5-25 μM for the determination of the two flavonols, based on the rate of their fluorescence decrease in alkaline medium, have been constructed and a kinetic method was developed. © 1983 Springer-Verlag

Isolation of quercetin and kaempferol from Rubus ulmifolius and their fluorometric assay

A fluorometric method for the determination of the flavonols quercetin and kaempferol in the leaves of Rubus ulmifolius was developed. A chromatographic technique for the isolation and separation of the two compounds was described. Working curves with standard solutions of quercetin and kaempferol at pH 2.5 were constructed. The effect of pH on the fluorescence intensity was studied with fluorescence measurements in acidic solutions of the compounds. The wavelengths for all fluorescence measurements were selected from fluorescence spectra of the two compounds. © 1982

Chemical constituents of rubus ulmifolius schott

From the leaves of Rubus ulmifolius Schott, quercetin, kaempferol, trifolin (kaempferol-3-0-galactoside), hyperin (quercetin-3-0-galactoside), chlorogenic acid, caffeic acid, a kaempferol-3-0-caffeoyl-ester, and a glucose-caffeoyl ester were isolated and identified. Free fatty acids were characterised by gas chromatography of their methyl esters. © 1981 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted

Spectrofluorimetric Determination Of Kinetic Parameters Of Bile Acids With 3α-Hydroxysteroid De-Hydrogenase From Mutant Pseudomonas Testosteroni

The spectrofluorimetric determination of kinetic parameters (Km, V and kobs) of conjugated bile acids with 3a-hydroxysteroid dehydrogenase from mutant Ps. Testosteroni is described.Under optimal pH conditions and pseudo- first order kinetics([3-NAD]> 20 KmNAD+) the kinetic parameters of bile acids in different buffers are determined. The bile acids exhibit larger kinetic differences in glycine and Tris buffer compared to those measured in pyrophosphate buffer.From these data it is concluded that under certain conditions the differential kinetic determination of one bile acid in the presence of others is possible without prior separation. © 1980, Taylor & Francis Group, LLC. All rights reserved

Constituents of the essential oil of satureia thymbra L., from different regions of Greece

Qualitative and quantitative determinations are reported for constituents of the essential oil of Satureia thymbra L., from different regions of Greece. © 1984 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted