Comparison of the constituents of Apocynum venetum and acidified Apocynum venetum by liquid chromatography–UV diode array detection–electrospray ionisation mass spectrometry

A liquid chromatography–electrospray ionization mass spectrometry (LC–ESI-MS) method was developed for the analysis and identification of constituents in plant extracts from the leaves of Apocynum venetum (AV) and acidified A. venetum (AAV). The content of the compounds in AV or its acidified product was found to be variable qualitatively and highly quantitatively. Seventeen major compounds were separated and identified from AV and AAV (Table 1). The identification of the constituents (compounds 1, 3, 5–7, 9–17) in the AV and AAV extracts was based on matching their LC retention time, UV spectrum and the detection of the molecular ions and the fragment ions of the compounds obtained from MS/MS experiments with those of authentic standards and data reported in the literature. The main difference between AV and AAV is that the extract of AV contains high level of quercetin-3-O-β-d-glucosyl-β-d-glucopyranosides, quercetin-3-O-glucuronide, quercetin-3-O-rutinoside, quercetin-3-O-glucoside, acetylated quercetin-3-O-galactoside, biapigenin and adhyperforin, while that of AAV had high contents of quercetin-3-O-galactoside, kaempferol-3-O-galactoside, amentoflavone and adhyperforin, which are the main constituents to differentiate AV and AAV.Table 1Major compound in extracts of AV and AAVCompoundStructureR1R2MFMWQuercetin-3-O-β-d-glucosyl-β-d-glucopyranosides[inline-graphic not available: see fulltext]O-MaltoseOHC27H30O17626Quercetin-3-O-glucuronideO-GlucuronideOHC21H18O13478Quercetin-3-O-rutinosideO-RutinoseOHC27H30O16610Quercetin-3-O-glucosideO-GlucoseOHC21H20O12464Quercetin-3-O-galactosideO-GalactoseOHC21H20O12464Quercetin-3-O-arabinofuranosideO-ArabinofuranoseOHC20H18O11434Ac-quercetin-3-O-glucosideO-[inline-graphic not available: see fulltext]OHC23H22O13506Ac-quercetin-3-O-galactosideO-[inline-graphic not available: see fulltext]OHC23H22O13506Kaempferol-3-O-glucosideO-GlucoseHC21H20O11448Kaempferol-3-O-galactosideO-GalactoseHC21H20O11448QuercetinOHOHC15H10O7302KaempferolOHHC15H10O6286CompoundStructureMFMWBiapigenin[inline-graphic not available: see fulltext]C30H18O10538Amentoflavone[inline-graphic not available: see fulltext]C30H18O10538CompoundStructureRMFMWHyperforin[inline-graphic not available: see fulltext]CH3C34H64O4536AdhyperforinCH2CH3C35H66O4550