title: Screening of protein kinase inhibitors in natural extracts by capillary electrophoresis combined with liquid chromatography-tandem mass spectrometry.
abstract: We report a capillary electrophoresis method in conjunction with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for screening of protein kinase inhibitors (PKIs) in natural extracts. Protein kinase A (PKA), substrate 5-carboxyfluorescein-labeled kemptide (CLK) and inhibitor H-89 were employed for the method development and validation. Enzymatic inhibition assay was performed with electrophoretically mediated microanalysis technique. Once the bioactivity of a natural extract was confirmed, an assay-guided isolation and structure elucidation using LC-MS/MS were accomplished to identify the compounds which are responsible for the observed bioactivity. Totally 33 natural extracts were screened with the method, and baicalin in the extract of Radix Scutellariae was identified to be a new PKI of PKA. This result demonstrated the practical applicability of our method in screening of PKIs from natural products.
authors.affiliation: Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Lingling Road 345, Shanghai 200032, China.
authors.forename: Tongdan
authors.initials: T
authors.lastname: Wang
authors.affiliation: Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Lingling Road 345, Shanghai 200032, China.
authors.forename: Qianqian
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Lingling Road 345, Shanghai 200032, China.
authors.forename: Yanmei
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Lingling Road 345, Shanghai 200032, China; ShanghaiTech University, Yueyang Road 319, Shanghai 200031, China. Electronic address: jingwu.kang@sioc.ac.cn.
authors.forename: Jingwu
authors.initials: J
authors.lastname: Kang
mesh_terms: D002853:Chromatography, Liquid / Q000379:methods; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D019075:Electrophoresis, Capillary / Q000379:methods; D005419:Flavonoids / Q000032:analysis; D010936:Plant Extracts / Q000737:chemistry*; D047428:Protein Kinase Inhibitors / Q000032:analysis*; D031364:Scutellaria baicalensis / Q000737:chemistry; D053719:Tandem Mass Spectrometry / Q000379:methods
chemical_list: D005419:Flavonoids; D010936:Plant Extracts; D047428:Protein Kinase Inhibitors; C038044:baicalin; D017868:Cyclic AMP-Dependent Protein Kinases
keywords: Capillary electrophoresis; Electrophoretically mediated microanalysis; LC–MS/MS; Natural extracts; Protein kinase inhibitors