Preparation of 6-125I-labeled amiloride derivatives

Dan Cassel, Miriam Rotman, Edward J. Cragoe, Peter Igarashi

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Amiloride and certain of its derivatives are effective inhibitors of Na H antiporters and of epithelial Na channels. We describe a simple method for the preparation of a variety of pharmacologically active 6-iodoamiloride derivatives that are labeled with 125I at high specific radioactivity. 6-Dechloroamiloride derivatives (bearing a hydrogen atom instead of the chlorine at the 6 position of the amiloride molecule) are reacted with 125ICl, prepared by the oxidation of the iodide in Na125I preparations. The 125I-labeled derivatives are separated from free 125I by anion exchange chromatography, or purified by thin layer chromatography. Both 6-dechloroamiloride and 5-(N-alkyl)-6-dechloroamiloride derivatives can be labeled by this method, with yields varying between 10 and 70%, depending on the ICl concentration and the structure of the 5-N-alkyl group. Efficient radiolabeling at high specific radioactivity also depends on the use of freshly prepared batches of 125I. Using carrier-free 125I, [125I]6-iodoamiloride and [125I]6-iodo-5-(N-tert-butyl)amiloride were prepared with yields of 27 and 22%, respectively. Potential applications of the 125I-labeled amiloride derivatives include ligand binding and affinity labeling experiments.

Original languageEnglish (US)
Pages (from-to)63-67
Number of pages5
JournalAnalytical biochemistry
Issue number1
StatePublished - Apr 1988


  • Amiloride
  • Na H exchange
  • Na channels
  • iodine monochloride
  • radioiodination
  • transport

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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