Phytochemical study: Fragmentation patterns of flavonoid-C-glycosides in the enriched flavonoids from corn silk using high-efficiency ultra-high-performance liquid chromatography combined with quadrupole time-of-flight mass spectrometry

Flavonoid-C-glycosides with various pharmacological actions were abundant in corn silk, and fragmentation in mass spectra of flavonoid-C-glycosides compounds was particularly important. This paper aimed to supervise the fragmentation patterns of flavonoid-C-glycosides in the enriched flavonoids from corn silk by high-efficiency ultra-high-performance liquid chromatography combined with a quadrupole time-of-flight mass spectrometry approach. Therefore, the flavonoids were extracted by heating reflux and then purified based on D101 macroporous resin. Thirty-five flavonoids were triumphantly identified in the purified product. Among them, 14 were flavonoid-C-glycosides, seven of them owned luteolin mother nuclei (luteolin-C-glycosides) and seven of them owned apigenin mother nuclei (apigenin-C-glycosides). Importantly, the diagnostic product ions of luteolin-C-glycosides including m/z (431, 413, 395, 369, 367, 313, and 299) and m/z (429, 411, 393, 367, 365, 311, and 297), and the characteristic product ions of apigenin-C-glycosides covered m/z (353, 339, and 299) and m/z (339, 327, and 309). In addition, diagnostic H2O neutral loss and glycosyl craking were familiar, and the difference values among product ions mainly contained 40, 60, 70, 80, 90, 100, and 120 Da. Thus, the fragmentations of luteolin-C-glycosides and apigenin-C-glycosides identified in corn silk were with proper regularity. The obtained fragmentation patterns provided rapid recognition and meaningful guidance for the purification study of flavonoid-C-glycosides.