UHPLC-ESI-Q-TOF-HRMS Quantitated Six C-Glycosyl Flavonoids in Oxalis corniculata and Demonstrated Their Typical...

Oxalis corniculata L. exhibits neuroprotection; however, its in vivo molecular profiling remains unclear. An ultra-high performance liquid chromatography-electrospray ionization-quadrupole-time-of-flight high resolution mass spectrometry (UHPLC-ESI-Q-TOF-HRMS) was established to determine and quantify six C-glycosyl flavonoids in the herb, namely swertisin, schaftoside, isoschaftoside, vitexin, isovitexin, and isoorientin. They were identified and confirmed in the aqueous extract of the herb with mass error less than 5 ppm in HRMS. The founded UHPLC-ESI-Q-TOF-HRMS was optimized and validated for biological samples analysis, with coefficient of determination R² greater than 0.998, matrix factor being near to 1, recoveries from 85.0% to 115.0% and relative standard deviation from 0.17% to 12.88%. Their simultaneous quantification for the first time by UHPLC-ESI-Q-TOF-HRMS indicated their contents to be from 47.7 to 455.5 mg/kg in the herb in dry weight. After a single oral administration of the saturated aqueous solution of the herb extract to rats, swertisin was typically quantified in rat brain, heart, liver, kidneys, lung, spleen, small intestine, bile, and excreta under multiple reaction monitoring. Schaftoside and isoschaftoside were quantitated in rat brain. Their in vivo molecular profiling in rats was illustrated, especially their penetration of rat blood-brain barrier. Totally 17 metabolites were identified in the biological samples.