Comprehensive Study of the Phenolics and Saponins from Helleborus niger L. Leaves and Stems by Liquid Chromatography/Tandem Mass Spectrometry

摘要

The aerial parts of the medicinal plant Helleborus niger L. comprise a substantial number of constituents with only few of them identified so far. To expand the knowledge of its secondary metabolite profile, extracts from H. niger leaves and stems were investigated by liquid chromatography/tandem mass spectrometry (LC/MS~n). Specific identification strategies using LC/MS are established and discussed in detail. The leaves turned out to contain acylated and non-acylated quercetin and kaempferol oligoglycosides, protoanemonin and its precursor ranunculin, β-ecdysone, and a variety of steroidal saponins, mainly in the furostanol form. The sapogenins were elucidated as of sarsasapogenyl, diosgenyl, and macranthogenyl structures, and confirmed by comparison with the respective reference compounds. The secondary metabolite profiles were almost identical in both plant parts except that the stems lacked kaempferol derivatives and some saponins. The ranunculin derivatives and β-ecdysone were found in both plant parts. Correlations between the location of the compound groups and the plant's defense strategies are proposed. Additionally, the role of the detected secondary metabolites as protective substances against exogenic stress and as a defense against herbivores is discussed.