Simultaneous quantification of multiple licorice flavonoids in rat plasma.

Area of Science:

• Analytical Chemistry
• Pharmacology
• Natural Products Chemistry

Background:

• Flavonoids are key polyphenols with antioxidant properties.
• Licorice flavonoids are bioactive compounds found in traditional Chinese medicine.
• Accurate quantification of flavonoids in biological matrices is crucial for pharmacokinetic studies.

Purpose of the Study:

• To develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantification of multiple licorice flavonoids in plasma.
• To optimize sample preparation and mobile phase conditions to minimize matrix effects and enhance detection limits.
• To demonstrate the method's applicability in a pharmacokinetic study.

Main Methods:

• Simultaneous quantification of six licorice flavonoids using LC-MS/MS with electrospray ionization.
• Optimization of the LC mobile phase with a low concentration of ammonium formate (HCOONH4) to mitigate "LC-electrolyte effects."
• Liquid-liquid extraction with ethyl acetate for plasma sample cleanup.

Main Results:

• The developed LC-MS/MS method achieved good linearity (0.32 ng/mL to 1 µg/mL) and high accuracy/precision (85-110% and 0.8-8.8%).
• A low concentration of ammonium formate in the mobile phase significantly improved detection limits and reduced matrix effects.
• Liquid-liquid extraction proved effective for sample cleanup, minimizing interference.
• The method was successfully applied to a pilot pharmacokinetic study of rats treated with Xiaochaihu-tang.

Conclusions:

• A robust and sensitive LC-MS/MS bioanalytical method for quantifying licorice flavonoids in plasma was successfully developed.
• The strategic use of ammonium formate in the LC mobile phase is a valuable technique for enhancing LC-MS/MS methods.
• This method provides a reliable tool for future pharmacokinetic and pharmacodynamic studies of licorice-derived compounds and herbal medicines.