A screening method for the identification of glycosylated flavonoids and other phenolic compounds using a standard analytical approach for all plant materials

A screening method was developed for the systematic identification of glycosylated flavonoids and other phenolic compounds in plant food materials based on an initial, standard analytical method. This approach applies the same analytical scheme (aqueous methanol extraction, reverse phase liquid chromatographic separation, and diode array and mass spectrometric detection) to every sample and standard. This standard approach allows the cross-comparison of compounds in samples, standards, and plant materials previously identified in the published literature. Thus, every analysis contributes to a growing library of data for retention times and UV/vis and mass spectra. Without authentic standards, this method provides provisional identification of the phenolic compounds: identification of flavonoid backbones, phenolic acids, saccharides, and acyls but not the positions of the linkages between these subclasses. With standards, this method provides positive identification of the full compound: identification of subclasses and linkages. The utility of the screening method is demonstrated in this study by the identification of 78 phenolic compounds in cranberry, elder flower, Fuji apple peel, navel orange peel, and soybean seed.