Objective To synthesize aristolochic acid Ⅰ(AAⅠ)-DNA adduct in vitro and to develop a method for the characterization of the adduct. Methods Aristolochic acid (AA) was incubated with 2′-Deoxyadenosine 5′-monophosphate in vitro using either enzymatic activation (by xanthine oxidase) or chemical activation (by zinc) to synthesize AAⅠ-DNA adduct. The AAⅠ-DNA adduct was characterized by the liquid chromatography electrospray ionization/tandem mass spectrometry (LC-ESI-MS/MS). Results AAⅠ-DNA adduct was prepared by two activation methods. Full scan spectra were obtained in the negative ion mode and the quasi-molecular ion peak was m/z 621. Analysis by electrospray ionization/tandem mass spectrometry (ESI-MS/MS) provided useful structural information about AAⅠ-DNA adduct. Conclusion AAⅠ can bind covalently to the exocyclic amino group of purine nucleotides to form AAⅠ-DNA adduct. LC/MS/MS is a practical tool to detect AAⅠ-DNA adduct.

By comparing with the molecule weights, retention times and product ion spectra of the standards, the cholic acid, deoxycholic acid and chenodeoxycholic acid were identified in the traditional Chinese compound medicine——“Qingkailing” injection by high performance liquid chromatography/mass spectrometry/mass spectrometry. Two other isomers of cholic acid and deoxycholic acid were also found, but tieir detail structure was still unknown due to the absence of standards. A quantitative method to determine cholic acid in the medicine was established and studied. An internal standard was used in quantitative analysis. When the concentration of cholic acid is from 875 ng/L to 140 μg/L, the chromatographic peak area and concentration are of good linear relation. The linear correlation coefficient was determined to be 0.9999 and the RSD is 2.04%. This method is simple, selective and highly sensitive, which is helpful for the quality control of traditional Chinese medicine.