title: Antidiarrheal efficacy of a quinazolin CFTR inhibitor on human intestinal epithelial cell and in mouse model of cholera.
abstract: OBJECTIVE
  This study aimed to evaluate the antidiarrheal efficacy and pharmacological properties of ethyl 2-(4-oxo-3-o-tolyl-3,4-dihydroquinazolin-2-ylthio)acetate (DQA) as an inhibitor of cystic fibrosis transmembrane conductance regulator protein (CFTR) both in vitro and in vivo.
  
  
  METHODS
  The effects of DQA on CFTR function and cell viability were investigated in Fisher rat thyroid (FRT) cells expressing human CFTR and human intestinal epithelial T84 cells by short-circuit current measurements and MTT assays, respectively. In vivo antidiarrheal efficacy of DQA was evaluated in a closed loop model of cholera in mice.
  
  
  RESULTS
  In permeabilized FRT cells, apical chloride current induced by CFTR agonists (10 μM forskolin, 100 μM CPT-cAMP, and 20 μM apigenin) was inhibited by DQA with IC(50) ~ 20 μM and complete inhibition at 200 μM. The inhibitory effect was reversible and not associated with cytotoxicity to FRT cells (5-500 μM DQA for 24 h). Likewise, DQA effectively inhibited both forskolin and cholera toxin-induced transepithelial chloride secretion in T84 cells. In mice, intraluminal injection of 100 μM DQA reduced cholera toxin (1 μg/closed loop)-induced intestinal fluid secretion by 85% without affecting intestinal fluid absorption.
  
  
  CONCLUSIONS
  DQA represents a new class of small molecule CFTR inhibitor with potential application in treatment of cholera.
authors.affiliation: Department of Physiology and Research Center of Transport Protein for Medical Innovation, Faculty of Science, Mahidol University, Bangkok, Thailand.
authors.forename: Jenvit
authors.initials: J
authors.lastname: Patanayindee
authors.forename: Chatchai
authors.initials: C
authors.lastname: Muanprasat
authors.forename: Sunhapas
authors.initials: S
authors.lastname: Soodvilai
authors.forename: Varanuj
authors.initials: V
authors.lastname: Chatsudthipong
mesh_terms: D000818:Animals; D000930:Antidiarrheals / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D002771:Cholera / Q000188:drug therapy* / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000037:antagonists & inhibitors* / Q000378:metabolism; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D051379:Mice; D008813:Mice, Inbred ICR; D011799:Quinazolines / Q000737:chemistry / Q000494:pharmacology / Q000627:therapeutic use*; D016896:Treatment Outcome
chemical_list: D000930:Antidiarrheals; C505032:CFTR protein, human; D011799:Quinazolines; D019005:Cystic Fibrosis Transmembrane Conductance Regulator
keywords: CFTR; CFTR inhibitor; chloride secretion; cholera; secretory diarrhea