title: A new method for identification of natural, artificial and in vitro cultured Calculus bovis using high-performance liquid chromatography-mass spectrometry.
abstract: OBJECTIVE
  Calculus bovis have been widely used in Chinese herbology for the treatment of hyperpyrexia, convulsions, and epilepsy. Nowadays, due to the limited source and high market price, the substitutes, artificial and in vitro cultured Calculus bovis, are getting more and more commonly used. The adulteration phenomenon is serious. Therefore, it is crucial to establish a fast and simple method in discriminating the natural, artificial and in vitro cultured Calculus bovis. Bile acids, one of the main active constituents, are taken as an important indicator for evaluating the quality of Calculus bovis and the substitutes. Several techniques have been built to analyze bile acids in Calculus bovis. Whereas, as bile acids are with poor ultraviolet absorbance and high structural similarity, effective technology for identification and quality control is still lacking.
  
  
  METHODS
  In this study, high-performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (LC/MS/MS) was applied in the analysis of bile acids, which effectively identified natural, artificial and in vitro cultured Calculus bovis and provide a new method for their quality control.
  
  
  RESULTS
  Natural, artificial and in vitro cultured Calculus bovis were differentiated by bile acids analysis. A new compound with protonated molecule at m/z 405 was found, which we called 3α, 12α-dihydroxy-7-oxo-5α-cholanic acid. This compound was discovered in in vitro cultured Calculus bovis, but almost not detected in natural and artificial Calculus bovis. A total of 13 constituents was identified. Among them, three bio-markers, including glycocholic acid, glycodeoxycholic acid and taurocholic acid (TCA) were detected in both natural and artificial Calculus bovis, but the density of TCA was different in two kinds of Calculus bovis. In addition, the characteristics of bile acids were illustrated.
  
  
  CONCLUSIONS
  The HPLC coupled with tandem MS (LC/MS/MS) method was feasible, easy, rapid and accurate in identifying natural, artificial and in vitro cultured Calculus bovis.
authors.affiliation: School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100029, China.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Liu
authors.affiliation: School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100029, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Tan
authors.affiliation: School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100029, China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Liu
authors.affiliation: School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100029, China.
authors.forename: Hang
authors.initials: H
authors.lastname: Shi
authors.affiliation: School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100029, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Feng
authors.affiliation: School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing 100029, China.
authors.forename: Qun
authors.initials: Q
authors.lastname: Ma
keywords: Artificial Calculus bovis; high-performance liquid chromatography-mass spectrometry; in vitro cultured Calculus bovis; natural Calculus bovis
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