title: Discovery of N-methyltetrahydroprotoberberines with κ-opioid receptor agonists-opioid receptor agonist activities from corydalis yanhusuo W. T. Wang by using two-dimensional liquid chromatography.
abstract: BACKGROUND
  The need for an efficacious analgesic without unwanted side effects is urgent. κ-opioid receptor agonists are known to exhibit potent analgesic effects and elicited fewer side effects than other opioid agonists. Thus in this study we chose the κ-opioid receptor as the target to identify the active components from traditional Chinese medicines (TCMs).
  
  
  METHODS
  The κ-opioid receptor was expressed in human embryonic kidney-293 T cells (HEK293T). Fluorometric Imaging Plate Reader (FLIPR) assay was used for the determination of Ca(2+) response when κ-opioid receptor was activated. A novel 2D separation system employing C18HCE as the first dimension and a strong cation exchange column (SCX) as the second dimension was conducted for the purification of the active principles.
  
  
  RESULTS
  With the aid of HPLC-based activity profiling, activities could be linked to two peaks from Corydalis yanhusuo W. T. Wang (C. yanhusuo) extract. Two N-methyltetrahydroprotoberberines with κ-opioid receptor agonist activities were isolated for the first time from C. yanhusuo by using 2D-LC.
  
  
  CONCLUSIONS
  Our study suggests that N-methyltetrahydroprotoberberines may serve as a new scaffold for κ-opioid receptor ligands. The strategy that we adopted can be applied to other naturally-occurring active alkaloids acting at different receptors.
authors.affiliation: Department of Pharmacology, University of California, Irvine, CA 92697, United States.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
authors.forename: Chaoran
authors.initials: C
authors.lastname: Wang
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
authors.forename: Zhimou
authors.initials: Z
authors.lastname: Guo
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
authors.forename: Xiuli
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Department of Pharmacology, University of California, Irvine, CA 92697, United States.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Key Laboratory of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; School of Pharmacy, East China University of Science and Technology, Shanghai 200237, China. Electronic address: liangxm@dicp.ac.cn.
authors.forename: Xinmiao
authors.initials: X
authors.lastname: Liang
authors.affiliation: Department of Pharmacology, University of California, Irvine, CA 92697, United States; Department of Pharmacological Sciences, University of California, Irvine, CA 92697, United States; Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, United States. Electronic address: ocivelli@uci.edu.
authors.forename: Olivier
authors.initials: O
authors.lastname: Civelli
mesh_terms: D001600:Berberine Alkaloids / Q000494:pharmacology*; D002853:Chromatography, Liquid / Q000379:methods; D031311:Corydalis; D057809:HEK293 Cells; D006801:Humans; D010936:Plant Extracts / Q000494:pharmacology*; D017473:Receptors, Opioid, kappa / Q000819:agonists*
chemical_list: D001600:Berberine Alkaloids; D010936:Plant Extracts; D017473:Receptors, Opioid, kappa
keywords: 2D separation; Corydalis yanhusuo W.T. Wang; GPCR; TCMs; κ-opioid receptor