Abstract: Objective: To separate and determine lipid-soluble and water-soluble metabolites of qucertin in the plasma of Kunming mice. Methods: Three week-old Kunming mice were administrated with quercetin at a dose of 100 mg/kg by gavage. Lipid-soluble and water-soluble metabolites of qucertin in mouse plasma were separated by elution with n-hexane/chloroform (1:1) and methanol, respectively. Then, the n-hexane/chloroform eluate was hydrolyzed by pancreatic lipase, and the methanol eluate simultaneously by sulfatase and β-glucuronidase. Lipid-soluble and water-soluble metabolites of qucertin in the plasma of Kunming mice were analyzed by tandem quadrupole-time of flight mass spectrometry in a negative ion mode based on gradient elution with a mobile phase composed of 0.1% formic acid (A) and acetonitrile (B). Results: In mouse plasma 84.38% of quercetin was metabolized to form esters, while only a small amount of water-soluble metabolites were found. Quercetin esters were the predominant metabolites in mouse plasma. Conclusions: The method is highly accurate and reproducible and can allow effective separation and determination of lipid-soluble and water-soluble metabolites of qucertin in plasma.

Key words: quercetin, quadrupole-time of flight (Q-TOF), lipid-soluble, metabolites