Individual Determination of Two Kinds of Flavonoids and Their Glycosides in Nepeta bracteata by HPLC

Objective: To establish two HPLC methods for determination content of luteolin, apigenin, and their glucosides such as luteolin-7-O-β-D-glucuronide (LGCRP), apigenin-7-O-glucuronide (AGCRP) in Nepeta bracteata. Methods: The determination was performed on C₁₈ column（250 mm×4.6 mm, 5 μm）with mobile phase consisted of acetonitrile-0.1% phosphoric acid solution (0.1:99.9, v/v) at the flow rate of 1.0 mL/min. The detection wavelength was 347 nm, and the column temperature was 30 ℃. The methods of pretreatment such as extraction solvent, amount of solvent, extraction time were optimized. Then, applicability of methods was investigated by system suitability test, linear relationship, limit of detection and limit of quantification inspection, precision, repeatability, stability, recovery test. Results: The linear ranges of luteolin, apigenin, LGCRP, AGCRP were 3.080~12.321, 4.753~19.010, 5.67~22.68, 9.97~39.86 μg/mL, r≥0.9993, the limit of detection were 0.11, 0.08, 0.03, 0.03 μg/mL, and the limit of quantification were 0.35, 0.23, 0.09, 0.10 μg/mL. The precision, repeatability and stability were good, the recovery were in the range of 98.8%~102.8%, 92.9%~98.1%, 93.9%~97.9%, 93.7%~97.3%. Conclusion: Both methods can be used for the quantitative determination of two flavonoids and their glycosides in Nepeta bracteata because there are simple operation, high sensitivity, good stability, high accuracy and strong applicability. Thus, it provide a basis for the formulation of the quality standard of Nepeta bracteata.