title: A cell-based, high-throughput homogeneous time-resolved fluorescence assay for the screening of potential κ-opioid receptor agonists.
abstract: OBJECTIVE
  The aim of this study was to identify κ-opioid receptor (KOR) agonists from a library of 80 000 small-molecule compounds and provide the experimental basis for the development of new analgesic candidates.
  
  
  METHODS
  The cell-based, high-throughput screen for human KOR agonists was based on the LANCE cAMP assay. Preliminary structure-activity relationship (SAR) analysis was applied according to the compounds' structures. An acetic acid twisting experiment was used to verify the pharmacodynamics.
  
  
  RESULTS
  In total, 31 compounds were identified as KOR agonists after preliminary and secondary screening. Of these compounds, five demonstrated significant KOR-stimulating activity that was comparable to U-50,488, a selective KOR agonist. The EC50 values for I-7, I-8, I-10, II-5, and II-8 were 13.34 ± 1.65, 14.01 ± 1.84, 9.57 ± 0.19, 14.94 ± 0.64, and 8.74 ± 0.72 nmol/L, respectively. Based on SAR studies, the stimulating activity of compounds with 5-phenyl-7-(trifluoromethyl)-4,5,6,7-tetrahydropyrazolo [1, 5-a] pyrimidine (group I) and 3,4-dimethoxy-N-(2-oxoethyl)-N-p-tolylbenzenesulfonamide (group II) parent structures were higher than the compound with a 5-hydroxy-2-methylbenzofuran-3-carboxylic acid (group III) parent structure. Pharmacodynamic experiments indicated that 20-40 μg/kg ip of compounds I-10 and II-8 significantly decreased the number of writhes induced by acetic acid; this finding is consistent with the SAR studies. Furthermore, the analgesic effects of compounds I-10 and II-8 were significantly antagonized in the presence of the selective KOR antagonist nor-BNI.
  
  
  CONCLUSIONS
  These findings collectively indicate that compounds I-10 and II-8 exhibit significant analgesic activities, providing evidence, at least in part, for their clinical application as new analgesic drugs.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wang
authors.forename: Ming
authors.initials: M
authors.lastname: Yan
authors.forename: Guang-Yao
authors.initials: GY
authors.lastname: Zheng
authors.forename: Ling
authors.initials: L
authors.lastname: He
authors.forename: Huan
authors.initials: H
authors.lastname: Yang
mesh_terms: D000700:Analgesics / Q000737:chemistry* / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D002460:Cell Line; D004353:Drug Evaluation, Preclinical / Q000379:methods*; D005260:Female; D005453:Fluorescence; D057166:High-Throughput Screening Assays / Q000379:methods*; D006801:Humans; D008297:Male; D051379:Mice; D010146:Pain / Q000188:drug therapy; D017473:Receptors, Opioid, kappa / Q000819:agonists*; D054852:Small Molecule Libraries / Q000737:chemistry* / Q000494:pharmacology* / Q000627:therapeutic use; D013050:Spectrometry, Fluorescence / Q000379:methods; D013329:Structure-Activity Relationship
chemical_list: D000700:Analgesics; D017473:Receptors, Opioid, kappa; D054852:Small Molecule Libraries