title: Untargeted analysis of sesquiterpene pyridine alkaloids from the dried roots of Tripterygium wilfordii using high-performance liquid chromatography/electrospray ionization tandem mass spectrometry.
abstract: BACKGROUND
  Sesquiterpene pyridine alkaloids are a large group of highly oxygenated sesquiterpenoids that have attracted attention in the fields of medicine because of their significant biological activities.
  
  
  METHODS
  Reference compounds including 14 sesquiterpene pyridine alkaloids and one dihydroagarofuran ester were analyzed by collision-induced dissociation tandem mass spectrometry (CID-MS/MS). A high-performance liquid chromatography/electrospray ionization (HPLC/ESI)-MS/MS method at two collision energies was adopted to investigate the botanical extracts of Tripterygium wilfordii.
  
  
  RESULTS
  For 15 reference compounds, in the high mass range, the product ions were formed by the loss of side chains or H2 O. In the low mass range, the high-abundance product ions at m/z 206, 204, or 194 were the characteristic ions of the pyridine moiety. The characteristic product ion at m/z 310 was formed through an ion-neutral complex intermediate. Fifty-four sesquiterpenoid derivatives, including 50 sesquiterpene pyridine alkaloids, were identified or tentatively characterized in botanical extracts of T. wilfordii based on their elemental constituents, characteristic fragmentation patterns, and the major product ion profiles of the reference compounds ascertained with HPLC/ESI-MS/MS at two collision energies. It seems that isocratic energy was appropriate for the untargeted analysis of compounds with molecular weights exceeding 800 Da, whereas a linear gradient energy vs molecular weight was suitable for those compounds with molecular weights below 800 Da.
  
  
  CONCLUSIONS
  The HPLC/ESI-MS/MS method, combining characteristic fragmentation patterns and the profiles of the product ions generated at different collision energies, is an effective technique for characterizing untargeted compounds.
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China.|Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences, Chengdu, 610041, China.|University of Chinese Academy of Sciences, Beijing, 100039, China.
authors.forename: Tian
authors.initials: T
authors.lastname: Cai
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China.
authors.forename: Ying-Gang
authors.initials: YG
authors.lastname: Luo
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhou
authors.affiliation: West China School of Pharmacy Sichuan University, Chengdu, 610041, China.|Chengdu University, Chengdu, 610106, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China.
authors.forename: Zhi-Jun
authors.initials: ZJ
authors.lastname: Wu
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China.
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Fang
authors.affiliation: Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, 610041, China.
authors.forename: Guo-Lin
authors.initials: GL
authors.lastname: Zhang
mesh_terms: D000470:Alkaloids / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D011725:Pyridines / Q000032:analysis*; D012717:Sesquiterpenes / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry / Q000379:methods; D029757:Tripterygium / Q000737:chemistry*
chemical_list: D000470:Alkaloids; D011725:Pyridines; D012717:Sesquiterpenes; C023666:pyridine