The mysteries of pharmacokinetics and in vivo metabolism of Oroxylum indicum (L.) Kurz: A new perspective from MSOP method

Abstract

The pharmacological effects of flavonoids in Oroxylum indicum (L.) Kurz against inflammation, bacterial, and oxidation have been well-documented. Additionally, it is commonly consumed as tea. However, the in vivo mechanism of its main compounds has not been well elucidated. In this study, a highly selective and sensitive UHPLC-Q-TOF-MS method combined with Mass Spectrum-based Orthogonal Projection (MSOP) theory and four-step analytical strategy was established and validated to identify metabolites in rats following oral administration Oroxylum indicum (L.) Kurz extract. Furthermore, a sensitive LC-MS/MS method was developed and validated for the first time to analyze the pharmacokinetics of ten main flavonoids in rats. Notably, a total of 47 metabolites were identified in blood, bile, urine, and feces samples. The maximum plasma concentration (Cmax) values for oroxin A, oroxin B, baicalin, chrysin, baicalein, scutellarein, apigenin, quercetin oroxylin A and isorhamnetin were 2945.1 ± 11.23 ng/mL, 3123.9 ± 16.37 ng/mL, 130.40 ± 27.52 ng/mL, 117.20 ± 28.54 ng/mL, 64.12 ± 19.33 ng/mL, 97.22 ± 24.27 ng/mL, 145.22 ± 29.92 ng/mL, 45.19 ± 18.84 ng/mL, 67.32 ± 15.78 ng/mL and 128.44 ± 26.42 ng/mL. A double peak was observed in the drug-time curve of apigenin, due to enterohepatic recirculation. This study demonstrated that MSOP method provided more technical support for the identification of flavonoid metabolites in complex system than traditional methods.

Keywords

• Oroxylum indicum (L.) Kurz
• Metabolites
• MSOP method
• Pharmacokinetic study
• UHPLC-Q-TOF/MS