ABSTRACT
ObjectiveUltra-high performance liquid chromatography-quadrupole-electrostatic field orbitrap high resolution mass spectrometry（UHPLC-Q-Orbitrap HRMS） was used to identify the metabolites of limonin in rats， and to explore the gender differences in the distribution of prototype components and metabolites in rats after single dose intragastric administration of limonin， as well as to speculate the metabolic pathways. MethodThe separation was performed on a Thermo Scientific Accucore™ C18 column（3 mm×100 mm， 2.6 μm） with 0.1% formic acid aqueous solution（A）-0.1% formic acid acetonitrile solution（B） as mobile phase in a gradient elution mode（0-1 min， 5%B； 1-6 min， 5%-20%B； 6-18 min， 20%-50%B； 18-23 min， 50%-80%B； 23-25 min， 80%-95%B； 25-30 min， 95%B） at a flow rate of 0.3 mL·min-1 and a column temperature of 30 ℃. MS data of biological samples were collected under the positive ion mode of electrospray ionization（ESI） and in the scanning range of m/z 100-1 500. Plasma， tissues（heart， liver， spleen， lung， kidney， stomach and small intestine）， urine and fecal samples were collected and prepared after intragastric administration， and the prototype component and metabolites of limonin were identified. ResultThe prototype component of limonin were detected in the feces， stomach， small intestine of female and male rats， and in the heart， liver， spleen， lung and kidney tissues of female rats. A total of 23 metabolites related to limonin were detected in rats， of which 2， 1， 5， 4， 23 metabolites were detected in liver， stomach， small intestine， urine and feces， respectively， and the main metabolic pathways were hydrolysis， reduction， hydroxylation and methylation， etc. The distribution of some metabolites differed between male and female rats. ConclusionThe prototype component of limonin are mainly distributed in the stomach and small intestine in rats， and the distribution of prototype component and some metabolites are different by gender. Limonin is mainly excreted through feces with phase Ⅰ metabolites as the main ones. The results of this study can provide a reference for further elucidation of the effect of gender differences on the metabolism of limonin in vivo and its mechanism of action.