title: Pyrazole compound BPR1P0034 with potent and selective anti-influenza virus activity.
abstract: BACKGROUND
  Influenza viruses are a major cause of morbidity and mortality around the world. More recently, a swine-origin influenza A (H1N1) virus that is spreading via human-to-human transmission has become a serious public concern. Although vaccination is the primary strategy for preventing infections, influenza antiviral drugs play an important role in a comprehensive approach to controlling illness and transmission. In addition, a search for influenza-inhibiting drugs is particularly important in the face of high rate of emergence of influenza strains resistant to several existing influenza antivirals.
  
  
  METHODS
  We searched for novel anti-influenza inhibitors using a cell-based neutralization (inhibition of virus-induced cytopathic effect) assay. After screening 20,800 randomly selected compounds from a library from ChemDiv, Inc., we found that BPR1P0034 has sub-micromolar antiviral activity. The compound was resynthesized in five steps by conventional chemical techniques. Lead optimization and a structure-activity analysis were used to improve potency. Time-of-addition assay was performed to target an event in the virus life cycle.
  
  
  RESULTS
  The 50% effective inhibitory concentration (IC50) of BPR1P0034 was 0.42 +/- 0.11 microM, when measured with a plaque reduction assay. Viral protein and RNA synthesis of A/WSN/33 (H1N1) was inhibited by BPR1P0034 and the virus-induced cytopathic effects were thus significantly reduced. BPR1P0034 exhibited broad inhibition spectrum for influenza viruses but showed no antiviral effect for enteroviruses and echovirus 9. In a time-of-addition assay, in which the compound was added at different stages along the viral replication cycle (such as at adsorption or after adsorption), its antiviral activity was more efficient in cells treated with the test compound between 0 and 2 h, right after viral infection, implying that an early step of viral replication might be the target of the compound. These results suggest that BPR1P0034 targets the virus during viral uncoating or viral RNA importation into the nucleus.
  
  
  CONCLUSIONS
  To the best of our knowledge, BPR1P0034 is the first pyrazole-based anti-influenza compound ever identified and characterized from high throughput screening to show potent (sub-microM) antiviral activity. We conclude that BPR1P0034 has potential antiviral activity, which offers an opportunity for the development of a new anti-influenza virus agent.
authors.affiliation: Department of Biochemistry, Chang Gung University, Taoyuan 333, Taiwan.
authors.forename: Shin-Ru
authors.initials: SR
authors.lastname: Shih
authors.forename: Tzu-Yun
authors.initials: TY
authors.lastname: Chu
authors.forename: Gadarla Randheer
authors.initials: GR
authors.lastname: Reddy
authors.forename: Sung-Nain
authors.initials: SN
authors.lastname: Tseng
authors.forename: Hsiun-Ling
authors.initials: HL
authors.lastname: Chen
authors.forename: Wen-Fang
authors.initials: WF
authors.lastname: Tang
authors.forename: Ming-sian
authors.initials: MS
authors.lastname: Wu
authors.forename: Jiann-Yih
authors.initials: JY
authors.lastname: Yeh
authors.forename: Yu-Sheng
authors.initials: YS
authors.lastname: Chao
authors.forename: John Ta
authors.initials: JT
authors.lastname: Hsu
authors.forename: Hsing-Pang
authors.initials: HP
authors.lastname: Hsieh
authors.forename: Jim-Tong
authors.initials: JT
authors.lastname: Horng
mesh_terms: D000818:Animals; D000998:Antiviral Agents / Q000737:chemistry / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004285:Dogs; D015195:Drug Design; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D009980:Influenza A virus / Q000187:drug effects; D009975:Orthomyxoviridae / Q000187:drug effects*; D011720:Pyrazoles / Q000737:chemistry / Q000494:pharmacology*; D014709:Vero Cells; D010948:Viral Plaque Assay; D014764:Viral Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000998:Antiviral Agents; C550382:BPR1P0034; D011720:Pyrazoles; D014764:Viral Proteins; C031280:pyrazole