title: A novel assessment of nefazodone-induced hERG inhibition by electrophysiological and stereochemical method.
abstract: Nefazodone was used widely as an antidepressant until it was withdrawn from the U.S. market in 2004 due to hepatotoxicity. We have investigated methods to predict various toxic effects of drug candidates to reduce the failure rate of drug discovery. An electrophysiological method was used to assess the cardiotoxicity of drug candidates. Small molecules, including withdrawn drugs, were evaluated using a patch-clamp method to establish a database of hERG inhibition. Nefazodone inhibited hERG channel activity in our system. However, nefazodone-induced hERG inhibition indicated only a theoretical risk of cardiotoxicity. Nefazodone inhibited the hERG channel in a concentration-dependent manner with an IC50 of 45.3nM in HEK-293 cells. Nefazodone accelerated both the recovery from inactivation and its onset. Nefazodone also accelerated steady-state inactivation, although it did not modify the voltage-dependent character. Alanine mutants of hERG S6 and pore region residues were used to identify the nefazodone-binding site on hERG. The hERG S6 point mutants Y652A and F656A largely abolished the inhibition by nefazodone. The pore region mutant S624A mildly reduced the inhibition by nefazodone but T623A had little effect. A docking study showed that the aromatic rings of nefazodone interact with Y652 and F656 via π-π interactions, while an amine interacted with the S624 residue in the pore region. In conclusion, Y652 and F656 in the S6 domain play critical roles in nefazodone binding.
authors.affiliation: Drug Discovery Platform Technology Research Group, Korea Research Institute of Chemical Technology, Daejeon, South Korea.
authors.forename: Dae-Seop
authors.initials: DS
authors.lastname: Shin
authors.affiliation: Drug Discovery Platform Technology Research Group, Korea Research Institute of Chemical Technology, Daejeon, South Korea.
authors.forename: Myoung Joo
authors.initials: MJ
authors.lastname: Park
authors.affiliation: Korea Institute of Toxicology, Korea Research Institute of Chemical Technology, Daejeon, South Korea.
authors.forename: Hyang-Ae
authors.initials: HA
authors.lastname: Lee
authors.affiliation: Drug Discovery Platform Technology Research Group, Korea Research Institute of Chemical Technology, Daejeon, South Korea.
authors.forename: Joo Yun
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Drug Discovery Platform Technology Research Group, Korea Research Institute of Chemical Technology, Daejeon, South Korea.
authors.forename: Hee-Chung
authors.initials: HC
authors.lastname: Chung
authors.affiliation: Drug Discovery Platform Technology Research Group, Korea Research Institute of Chemical Technology, Daejeon, South Korea.
authors.forename: Dae Seok
authors.initials: DS
authors.lastname: Yoo
authors.affiliation: Drug Discovery Platform Technology Research Group, Korea Research Institute of Chemical Technology, Daejeon, South Korea.
authors.forename: Chong Hak
authors.initials: CH
authors.lastname: Chae
authors.affiliation: College of Veterinary Medicine, Kyungpook National University, Daegu, South Korea.
authors.forename: Sang-Joon
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Korea Institute of Toxicology, Korea Research Institute of Chemical Technology, Daejeon, South Korea.
authors.forename: Ki-Suk
authors.initials: KS
authors.lastname: Kim
authors.affiliation: Drug Discovery Platform Technology Research Group, Korea Research Institute of Chemical Technology, Daejeon, South Korea. Electronic address: mbae@krict.re.kr.
authors.forename: Myung Ae
authors.initials: MA
authors.lastname: Bae
mesh_terms: D001665:Binding Sites; D054715:Cardiotoxins / Q000737:chemistry*; D003198:Computer Simulation; D000072237:ERG1 Potassium Channel; D055724:Electrophysiological Phenomena; D051638:Ether-A-Go-Go Potassium Channels / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D018408:Patch-Clamp Techniques; D010879:Piperazines; D011487:Protein Conformation; D013237:Stereoisomerism; D014230:Triazoles / Q000737:chemistry*
chemical_list: D054715:Cardiotoxins; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; D010879:Piperazines; D014230:Triazoles; C051752:nefazodone
keywords: Cardiotoxicity; HEK-293 cells; Nefazodone; Patch clamp; hERG