Simultaneous Determination of Six Compounds by UHPLC–MS/MS: Comparison of Pharmacokinetics of <scp> <i>Syringa oblata</i> </scp> Lindl. Leaf Extract in Normal and Ulcerative Colitis Rats After Oral Administration

Syringa oblata Lindl. leaf extract has a long history of use with pharmacological properties such as heat-clearing, detoxifying, and anti-inflammatory effects. In this study, an ulcerative colitis (UC) animal model was established and compared with a normal group. The study simultaneously determined 6 components of S. oblata Lindl. leaf extract (protocatechuic acid, caffeic acid, quercetin 3-O-β-D-glucopyranoside, (8E)-ligstroside, oleuropein, and oleacein) in the plasma of rats. The results showed that the extract exhibited good biological utilization in both groups, with stable metabolism of the six components, maintaining effective plasma concentrations. Pharmacokinetic analysis suggested the extract's potential for UC treatment. The relative standard deviation (RSD) of precision and accuracy for the six components was below 13%, and the lower limits of quantification (LLOQ) were 5.10, 5.10, 10.2, 10.1, 3.39, and 3.18 ng/mL, respectively. The method met FDA bioanalytical validation criteria for stability, matrix effects, and extraction recovery. Significant pharmacokinetic differences between UC and normal rats were observed, highlighting the extract's potential for clinical application and health product development, offering a promising therapeutic option for UC.