Analysis of aristolochic acid in asarum (Xixin) and its preparations by liquid chromatography/tandem mass spectrometry

Abstract

A method for analysis of aristolochic acids (AAs: AA-I, AA-II) in Asarum (Xixin, named in Chinese) and its preparations by liquid chromatography coupled with tandem mass spectrometry has been developed. The chromatographic analysis was carried out using a C18 column (2.1x150 mm) and a mixture of 0.1% formic acid (containing 0.1% ammonium acetate) and acetonitrile (65:35, v/v) as the mobile phase at a flow rate of 0.3 mL/min. Piromidic acid was used as an internal standard. The mass detection was measured as the positive ion electrospray ionization mode. The precursor and daughter ions for quantitation were m/z 359 and 298 for AA-I, m/z 329 and 268 for AA-II. The instrument detection limit of AA-I and AA-II was 2 and 2.8 ng/mL, respectively. The result showed that Asarum contained AA-I while AA-II was not detected. AA-I distribution in different parts of Asarum was examined in detail and AA-I content in both methanol and water extracts was also compared in this study. In our twenty samples of Asarum, the average amounts of AA-I in 75% methanol extracts of roots, rhizomes, petioles and leaves were 1.23 ± 0.64, 1.72 ± 1.38, 7.81 ± 4.04 and 27.13 ± 25.31 ppm, respectively. The average amounts of AA-I in water extracts of roots, rhizomes, petioles and leaves were 0.33 ± 0.32, 0.45 ± 0.50, 3.98 ± 3.09 and 6.32 ± 9.75 ppm, respectively. The results indicated that the amounts of AA-I in roots were less than those in petioles and leaves, and the amounts of AA-I in water extracts were about 25 to 50 percent of those in 75% methanol extracts. For Asarum preparations, the amounts of AA-I in each six of Xi-xin-extract- powder and Ma-Huang-Fu-Zi-Xi-Xin-Tang ranged between 0.35-2.07 ppm and 0.21-1.00 ppm, respectively. Results of this study could be provided for the regulatory authority as references.