Characterization of flavone glycosides and aglycones in Cephalotaxus sinensis by HPLC-DAD-MS

High performance liquid chromatography diode array detector electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS) was utilized to separate and identify flavone glycosides and aglycones in Cephalotaxus sinensis, a natural plant with an anti-hyperglycemic effect. The HPLC-DAD-ESI-MS system could provide a great amount of information on the structure of flavone aglycones and glycosides in C. sinensis without time-consuming pre-separation or purification procedures. A total of seven flavone glycosides and two flavone aglycones were unambiguously identified based on their retention times, ultraviolet spectra, molecular weights and MS/MS spectra. It's interesting that five 5-O-flavone glycosides were found in C. sinensis since 5-O-flavone glycosides are rare and difficult to form in the natural plant. Among them, quercitrin and apigenin-5-O-β-d-glucopyranoside were isolated from this genus for the first time. A novel flavone glycoside, chryoseriol-5-O-[α-l- rhamnopyranosyl-(1→4)-β-D-6-O-acetylglucopyranoside], was isolated for the first time and identified by the ultraviolet spectrum, infrared spectrum, mass spectrum and nuclear magnetic resonance spectrum. In addition, the proposed fragment pathway of the novel flavone glycoside was concluded in the negative ionization mode by HPLC-ESI-MS/MS.