ABSTRACT
The major flavonol glycosides of ripe blackcurrants (Ribes nigrum cv. Silvergieters Schwarze), myricetin 3-beta-D-glucopyranoside, rutin, and isoquercitrin, have been isolated in crystalline form. Analysis by thin-layer chromatography confirmed the occurrence of the 3-rutinosides and 3-glucosides of cyanidin and delphinidin. No free flavonoid aglycones could, however, be detected in the fresh berries. The major constituent fluorescing blue under ultraviolet light on paper and cellulose thin-layer chromatograms, was isolated and characterized as 1-O-caffeyl-beta-D-glucopyranose. Also isolated were 1-O-ferulyl- and 1-O-p-coumaryl-beta-D-glucopyranose. The occurrence fo hydroxycinnamyl-D-glucoses in blackcurrants does not appear to have been recognized previously.
Subject(s)
Cinnamates/analysis , Coumaric Acids/analysis , Flavonoids/analysis , Fruit/analysis , Glucosides/analysis , Glycosides/analysis , Phenols/analysis , Chromatography, Thin Layer , Magnetic Resonance Spectroscopy , SpectrophotometryABSTRACT
1. The isolation of aspalathin, the principal phenolic constituent in the leaves of Aspalathus linearis, is described and its properties are discussed. 2. The compound has been identified as 3'-C-beta-d-glucopyranosyl-2',3,4,4',6'-pentahydroxydihydrochalcone by the preparation and analysis of various derivatives, by photochemical oxidation to 2,3-dihydroiso-orientin and by nuclear-magnetic-resonance studies.