title: Determination of kinetic parameters and structure-activity relationships of ginsenosides as inhibitors of cyclin-dependent kinase 5/p25 using ultra-pressure liquid chromatography with triple quadrupole tandem mass spectrometry.
abstract: BACKGROUND
  Cyclin-dependent kinase 5 (cdk5) is a serine/threonine kinase that is reported to play an important role in the pathogenesis of Alzheimer's disease. Ginsenosides have beneficial effects on Alzheimer's disease in both in vivo and in vitro experiments, but the precise mechanisms are not yet entirely clear.
  
  
  METHODS
  In the present study, an ultrahigh-pressure liquid chromatography (UPLC) and triple quadrupole mass spectrometry (TQMS) assay was developed to study the activities of cdk5 for the first time.
  
  
  RESULTS
  The calibration curves showed a good linear behavior over the range 0.04 μM to 10 μM (y = 0.934x + 0.045, R(2) = 0.995) with product phosphorylated peptide (PKpTPKKAKKV). The screening results suggested that the inhibition activities of ginsenosides are related to their chemical structures.
  
  
  CONCLUSIONS
  The developed UPLC/TQMS-based method for determination of an inhibitor of cdk5/p25 is sensitive and reliable. The effect of ginsenosides on Alzheimer's disease may be involved with the regulation of activities of cdk5/p25.
authors.affiliation: Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun Center of Mass Spectrometry, Changchun, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Chen
authors.forename: Hongmei
authors.initials: H
authors.lastname: Yang
authors.forename: Jun
authors.initials: J
authors.lastname: Niu
authors.forename: Shuying
authors.initials: S
authors.lastname: Liu
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods; D051360:Cyclin-Dependent Kinase 5 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004353:Drug Evaluation, Preclinical / Q000379:methods; D057075:Enzyme Assays / Q000379:methods; D036145:Ginsenosides / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D013329:Structure-Activity Relationship; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D036145:Ginsenosides; D051360:Cyclin-Dependent Kinase 5