title: Isolation and identification of flavonoids, including flavone rotamers, from the herbal drug 'Crataegi folium cum flore' (hawthorn).
abstract: Twelve flavonoids, including seven flavones, four flavonols and one flavanone, were isolated from methanolic extract of the herbal drug 'Crataegi folium cum flore' (hawthorn leaves and flowers) by a combination of CC (over Amberlite XAD-7 and Sephadex LH-20) and preparative HPLC. Their structures, including that of the novel flavonol 8-methoxykaempferol 3-O-(6"-malonyl-beta-glucopyranoside), were elucidated by homo- and heteronuclear NMR and electrospray/MS. The 1H- and 13C-NMR of all compounds, including rotameric pairs of five flavone C-glycosides, were assigned. The presence and relative proportion of each rotamer was shown by various NMR experiments, including two-dimensional nuclear Overhauser and exchange spectroscopy, to depend on solvent, linkage position and structure of the C-glycosyl substituent.
authors.affiliation: Department of Chemistry, University of Bergen, Norway.
authors.forename: S
authors.initials: S
authors.lastname: Rayyan
authors.forename: T
authors.initials: T
authors.lastname: Fossen
authors.forename: H
authors.initials: H
authors.lastname: Solheim Nateland
authors.forename: O M
authors.initials: OM
authors.lastname: Andersen
mesh_terms: D002851:Chromatography, High Pressure Liquid; D027825:Crataegus / Q000737:chemistry*; D005419:Flavonoids / Q000032:analysis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D010946:Plants, Medicinal / Q000737:chemistry*
chemical_list: D005419:Flavonoids