title: A proposed biosynthetic pathway of picrosides linked through the detection of biochemical intermediates in the endangered medicinal herb Picrorhiza kurroa.
abstract: BACKGROUND
  Picrorhiza kurroa Royle ex Benth is an important medicinal herb used in the preparation of several herbal drug formulations due to the presence of picroside-I (P-I) and picroside-II (P-II) along with other iridoid-glucosides derivatives.
  
  
  OBJECTIVE
  The endangered status of P. kurroa coupled with lack of information on biosynthesis of P-I and P-II necessitate deciphering the biosynthetic pathway for picrosides.
  
  
  METHODS
  LC with electrospray ionisation (ESI) and quadrupole time of flight combined with MS/MS was used to detect intermediates and assemble the picrosides biosynthetic pathway in P. kurroa.
  
  
  RESULTS
  The presence of catalpol and aucubin, the major backbone structures of picrosides, along with intermediate metabolites boschnaloside, bartsioside and mussaenosidic acid, was confirmed in ESI negative mode with pseudomolecular ion peaks, that is, m/z 361, m/z 343, m/z 345, m/z 329 and m/z 375 ions and their fragmentation patterns.
  
  
  CONCLUSIONS
  The picrosides biosynthetic pathway is expected to provide a reliable platform towards understanding the molecular components (genes/enzymes) of P-I and P-II biosynthesis in P. kurroa for their eventual utilisation in various applications.
authors.affiliation: Department of Pharmacy, Jaypee University of Information Technology, Waknaghat, Solan, 173234, Himachal Pradesh, India.
authors.forename: Varun
authors.initials: V
authors.lastname: Kumar
authors.forename: Hemant
authors.initials: H
authors.lastname: Sood
authors.forename: Manu
authors.initials: M
authors.lastname: Sharma
authors.forename: Rajinder Singh
authors.initials: RS
authors.lastname: Chauhan
mesh_terms: D002853:Chromatography, Liquid; D002934:Cinnamates / Q000378:metabolism*; D057888:Iridoid Glucosides / Q000032:analysis* / Q000378:metabolism*; D032261:Picrorhiza / Q000378:metabolism*; D010946:Plants, Medicinal / Q000378:metabolism*; D027343:Rhizome / Q000378:metabolism; D053719:Tandem Mass Spectrometry
chemical_list: D002934:Cinnamates; D057888:Iridoid Glucosides; C078040:catalpol; C109270:picroside I; C006650:aucubin; C416837:picroside II
keywords: LC-MS; Picrorhiza kurroa; aucubin; bartsioside; biosynthetic pathway; picrosides