Quantitative Analysis of Two Isoflavones in Pueraria Lobata Flowers from Eleven Chinese Provinces Using High Performance Liquid Chromatography

Background: Pueraria lobata flower (Gehua) is a medicinal herb to treat intoxication, hepatic and gastrointestinal tractlesion induced by alcohol. This study aims to develop a new HPLC method for the determination of two majorisoflavones in P. lobata flowers, namely tectoridin and 6"-O-xylosyl-tectoridin.Methods: A high performance liquid chromatography (HPLC) method with a C18 column (250 mm × 4.6 mm, 5 μm)was developed for the quantitative analysis of tectoridin and 6"-O-xylosyl-tectoridin, the main isoflavone componentsin P. lobata flower. A simple gradient of acetonitrile/water (0 min 15:85; 35 min 50:50; 36 min 15:85; 40 min 15:85; v/v)was used, and 265 nm was selected as detection wavelength. Tectoridin and 6"-O-xylosyl-tectoridin were used as theexternal standards in quality control of P. lobata flower for the first time. The method was applied to practical use inquality assessment of eleven batches of P. lobata flower samples in Chinese herbal medicine market.Results: The peak area response was linear for tectoridin in the 11.8-236.4 μg/mL range with a correlation coefficient of0.9996 (P < 0.001), and for 6"-O-xylosyl-tectoridin in the 10.33-185.99 μg/mL range with a correlation coefficient of0.9984 (P < 0.001) respectively. The average recoveries were 102.7-103.7% for tectoridin and 95.7-103.2% for 6"-Oxylosyl-tectoridin (RSDs < 3%), and the intra-day and inter-day RSDs of the two components were less than 2%. ThisHPLC method was applied to assess the quality of P. lobata flower from eleven provinces in China. P. lobata flowers fromnorthern China contained 26.46-43.28 mg/g of tectoridin and 30.90-48.23 mg/g of 6"-O-xylosyl-tectoridin comparingto 10.00-19.81 mg/g of tectoridin and 11.08-37.03 mg/g of 6"-O-xylosyl-tectoridin in those from southern China.Conclusion: The results showed that P. lobata flowers from northern China contained more tectoridin and 6"-Oxylosyl-tectoridin than those from southern China.