Identification of C-glycosyl flavones by high performance liquid chromatography electrospray ionization mass spectrometry and quantification of five main C-glycosyl flavones in Flickingeria fimbriata

Flickingeria fimbriata is commonly applied in China as a traditional Chinese medicine (TCM), however the quality control of it is incomplete. In this work, we aim to identify and quantify the structures of C-glycosyl flavones in F. fimbriata. High performance liquid chromatography-diode array detector (HPLC-DAD) and High performance liquid chromatography–electrospray ionization–multiple stage tandem mass spectrometry (HPLC–ESI–MS(n)) methods were combined to identify C-glycosyl flavones and determine their contents. Twenty acylated C-glycosyl flavones and ten non-acylated C-glycosyl flavones were identified for the first time in F. fimbriata on systematic MS(n) analysis via HPLC–ESI–MS(n). The aglycones of all of these compounds were apigenin or chrysoeriol and were acylated with p-coumaric, ferulic, 3,4-dimethoxycinnamic or 3,4,5-trimethoxycinnamic acids. Furthermore, the quantification result suggest that two C-glycosyl flavones (vicenin-I and vicenin-III) with relative high contents were revealed to be more strongly acylated in F. fimbriata. The method is sufficiently precise, accurate, and sensitive for the qualitative and quantitative analysis of C-glycosyl flavones, which is expected to establish a standard for quality control and identification in this plant.