Study of the Contents of Analogues of Aristolochic Acid in Houttuynia cordata by Ultra-High Performance Liquid Chromatography Tandem Mass Spectrometry

In this study, a new and simple method was established for the simultaneous determination of analogues of aristolochic acids (aristolochic acid I, aristolochic acid II, aristolactam I and aristolactam AII) in Houttuynia cordata by ultra-high performance liquid chromatography-quadrupole/time-of-flight mass spectrometry (UHPLC-Q/TOF-MS). The samples were ultrasonically extracted with methanol, purified with HC-C18, and then separated on a C18 column (75 x 2.1 mm, 2.0 mu m) at 35 degrees C. Under the optimized conditions, aristolochic acid I (AA-I), aristolochic acid II (AA-II), aristolactam I (AL-I) and aristolactam AII (AL-AII) all showed good linear regression (not less than 0.9987). The average recoveries of the four analytes were within the range of 72.3-105.5%, with the relative standard deviations (RSDs) being <= 7.6%. The proposed method was then applied to the determination of Houttuynia cordata samples collected from different regions in China. The results showed that none of the three carcinogenic substances (aristolochic acid I, aristolochic acid II and aristolactam I) were detected in any of the 22 samples collected from 22 different regions of China, while aristolactam AII, which has not been reported to have genotoxicity, was detected in all samples. This study provides a valuable reference for the further safety assessment of Houttuynia cordata.