title: Rehabilitating drug-induced long-QT promoters: in-silico design of hERG-neutral cisapride analogues with retained pharmacological activity.
abstract: BACKGROUND
  The human ether-a-go-go related gene 1 (hERG1), which codes for a potassium ion channel, is a key element in the cardiac delayed rectified potassium current, IKr, and plays an important role in the normal repolarization of the heart's action potential. Many approved drugs have been withdrawn from the market due to their prolongation of the QT interval. Most of these drugs have high potencies for their principal targets and are often irreplaceable, thus "rehabilitation" studies for decreasing their high hERG1 blocking affinities, while keeping them active at the binding sites of their targets, have been proposed to enable these drugs to re-enter the market.
  
  
  METHODS
  In this proof-of-principle study, we focus on cisapride, a gastroprokinetic agent withdrawn from the market due to its high hERG1 blocking affinity. Here we tested an a priori strategy to predict a compound's cardiotoxicity using de novo drug design with molecular docking and Molecular Dynamics (MD) simulations to generate a strategy for the rehabilitation of cisapride.
  
  
  RESULTS
  We focused on two key receptors, a target interaction with the (adenosine) receptor and an off-target interaction with hERG1 channels. An analysis of the fragment interactions of cisapride at human A2A adenosine receptors and hERG1 central cavities helped us to identify the key chemical groups responsible for the drug activity and hERG1 blockade. A set of cisapride derivatives with reduced cardiotoxicity was then proposed using an in-silico two-tier approach. This set was compared against a large dataset of commercially available cisapride analogs and derivatives.
  
  
  CONCLUSIONS
  An interaction decomposition of cisapride and cisapride derivatives allowed for the identification of key active scaffolds and functional groups that may be responsible for the unwanted blockade of hERG1.
authors.affiliation: Centre for Molecular Simulations and Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada. serdardurdagi@gmail.com.
authors.forename: Serdar
authors.initials: S
authors.lastname: Durdagi
authors.forename: Trevor
authors.initials: T
authors.lastname: Randall
authors.forename: Henry J
authors.initials: HJ
authors.lastname: Duff
authors.forename: Adam
authors.initials: A
authors.lastname: Chamberlin
authors.forename: Sergei Y
authors.initials: SY
authors.lastname: Noskov
mesh_terms: D020117:Cisapride / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology*; D015195:Drug Design; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels / Q000378:metabolism*; D005765:Gastrointestinal Agents / Q000009:adverse effects / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D008133:Long QT Syndrome / Q000139:chemically induced; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D043705:Receptor, Adenosine A2A / Q000378:metabolism*; D044422:Receptors, Serotonin, 5-HT4 / Q000378:metabolism
chemical_list: D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D005765:Gastrointestinal Agents; C000606913:KCNH2 protein, human; D043705:Receptor, Adenosine A2A; D044422:Receptors, Serotonin, 5-HT4; D020117:Cisapride