Synthesis of novel progestin-rhenium conjugates as potential ligands for the progesterone receptor

Bioorg Med Chem. 1999 Sep;7(9):1827-35. doi: 10.1016/s0968-0896(99)00119-4.


To assist in the development of technetium-based radiopharmaceuticals that are useful for the diagnostic imaging of steroid receptor-positive breast tumors, we have synthesized a series of small-sized metal chelates according to 'n + 1' mixed-ligand, thioether-carbonyl and organometallic designs. In these preliminary investigations, rhenium was used as a model for the radioactive technetium. The metal chelates contain the rhenium metal in several oxidation states, being + 5, + 3, and + 1, and they were attached to 21-substituted progesterone derivatives. A competitive receptor-binding assay (rat uterine cytosol, 0 degrees C) was used to determine the binding affinity of these conjugates for the progesterone receptor. The highest affinity of 9% (RU5020 = 100%) was obtained with a '3 + 1' mixed-ligand complex, containing a NMe group as the central donor atom in the tridentate ligand part. This value reflects a relative binding affinity of 75% compared with the parent steroid progesterone.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crystallography, X-Ray
  • Ligands
  • Progestins / chemistry*
  • Progestins / metabolism
  • Receptors, Progesterone / metabolism*
  • Rhenium / chemistry*
  • Rhenium / metabolism
  • Spectrum Analysis


  • Ligands
  • Progestins
  • Receptors, Progesterone
  • Rhenium