Liquid chromatographic analysis of flavonol compounds in green fruits of three Rhamnus species used in Stil de grain

Flavonol compounds present in green fruits of Rhamnus species (Rhamnus saxatilis, Rhamnus alatemus and Rhamnus catharticus) were studied. The objective is to compare the chemical composition of the three Rhamnus species in order to distinguish them. Liquid chromatography was employed for the separation of the analytes and the detector is an ion trap mass spectrometer in positive ESI mode. The aglycones part was constituted by usual flavonols as quercetin, kaempferol, isorhamnetin, rhamnetin, rhamnocitrin and rhamnazin while heterosidic part was an O-rhamninoside or O-acetyl-rhamninoside linked in position 3 or 4' on flavonol skeleton. The UV/Visible spectroscopy has permitted to determine the glycosylation site on the flavonol, and liquid chromatography was used to confirm the glycoside sequence and aglycone part. Each Rhamnus species was characterized by leading compounds as O-acetyl-rhamninoside derivatives for R. saxatilis, 4'-O-rhamninoside for R. alaternus and R. catharticus. Quercetin-4'-O-rhamninoside is only present in R. alaternus species permitting to discriminate it. (C) 2014 Elsevier B.V. All rights reserved.