Characterization of Flavonols in Cranberry (Vaccinium macrocarpon) Powder

Abstract

Flavonoids were extracted from cranberry powder with acetone and ethyl acetate and subsequently fractionated with Sephadex LH-20 column chromatography. The fraction eluted with a 60% methanol solution was composed primarily of phenolic constituents with maximum absorbance at 340 nm. A high-performance liquid chromatography procedure was developed, which resolved 22 distinct peaks with UV/vis and mass spectra corresponding to flavonol glycoside conjugates. Six new constituents not previously reported in cranberry or in cranberry products were determined through NMR spectroscopy to be myricetin-3-β-xylopyranoside, quercetin-3-β-glucoside, quercetin-3-α-arabinopyranoside, 3‘-methoxyquercetin-3-α-xylopyranoside, quercetin-3-O-(6‘ ‘-p-coumaroyl)-β-galactoside, and quercetin-3-O-(6‘ ‘-benzoyl)-β-galactoside. Quercetin-3-O-(6‘ ‘-p-coumaroyl)-β-galactoside and quercetin-3-O-(6‘ ‘-benzoyl)-β-galactoside represent a new class of cranberry flavonol compounds with three conjugated components consisting of a flavonol, sugar, and carboxylic acid (benzoic or hydroxycinnamic acids). This is also the first report identifying quercetin-3-arabinoside in both furanose and pyranose forms in cranberry. Elucidation of specific flavonol glycosides in cranberry is significant since the specificity of the sugar moiety may play a role in the bioavailability of the flavonol glycosides in vivo. Keywords: Vaccinium macrocarpon Ait.; cranberry; flavonol glycosides; quercetin; myricetin; arabinopyranoside; acylated quercetin-3-glycosides