Benzoflavone activators of the cystic fibrosis transmembrane conductance regulator: towards a pharmacophore model for the nucleotide-binding domain

Bioorg Med Chem. 2003 Sep 1;11(18):4113-20. doi: 10.1016/s0968-0896(03)00435-8.


Our previous screen of flavones and related heterocycles for the ability to activate the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel indicated that UCCF-029, a 7,8-benzoflavone, was a potent activator. In the present study, we describe the synthesis and evaluation, using cell-based assays, of a series of benzoflavone analogues to examine structure-activity relationships and to identify compounds having greater potency for activation of both wild type CFTR and a mutant CFTR (G551D-CFTR) that causes cystic fibrosis in some human subjects. Using UCCF-029 as a structural guide, a panel of 77 flavonoid analogues was prepared. Analysis of the panel in FRT cells indicated that benzannulation of the flavone A-ring at the 7,8-position greatly improved compound activity and potency for several flavonoids. Incorporation of a B-ring pyridyl nitrogen either at the 3- or 4-position also elevated CFTR activity, but the influence of this structural modification was not as uniform as the influence of benzannulation. The most potent new analogue, UCCF-339, activated wild-type CFTR with a K(d) of 1.7 microM, which is more active than the previous most potent flavonoid activator of CFTR, apigenin. Several compounds in the benzoflavone panel also activated G551D-CFTR, but none were as active as apigenin. Pharmacophore modeling suggests a common binding mode for the flavones and other known CFTR activators at one of the nucleotide-binding sites, allowing for the rational development of more potent flavone analogues.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apigenin
  • Benzoflavones / chemical synthesis*
  • Benzoflavones / pharmacology
  • Binding Sites
  • Cells, Cultured
  • Cystic Fibrosis Transmembrane Conductance Regulator / chemistry
  • Cystic Fibrosis Transmembrane Conductance Regulator / drug effects*
  • Cystic Fibrosis Transmembrane Conductance Regulator / metabolism
  • Flavonoids / pharmacology
  • Green Fluorescent Proteins
  • Humans
  • Luminescent Proteins
  • Models, Molecular
  • Molecular Conformation
  • Nucleotides / chemistry
  • Nucleotides / metabolism*
  • Rats
  • Structure-Activity Relationship


  • Benzoflavones
  • CFTR protein, human
  • Flavonoids
  • Luminescent Proteins
  • Nucleotides
  • Cystic Fibrosis Transmembrane Conductance Regulator
  • Green Fluorescent Proteins
  • Apigenin