Ligand binding kappa-selective

The majority of studies aimed at preparing kappa-selective opioids have used U-50488 (5) as the chemical lead and, as the above discussion shows, this has proved to be a highly productive approach. However, as was pointed out above, there are other structures [EKC (3), tifluadom (6) and the peptide dynorphin (7)] which have been reported to bind to the kappa receptor, albeit with poor opioid receptor subtype selectivity. Some attempts have been made to develop kappa-selective ligands from these structures and they are summarized here. 

TABLE 3 Activity of Kappa-Selective Ligands in Opioid Receptor Binding Assays and Kappa GTPy[35S] Assay... 

Benyhe S, Marki A, Nachtsheim C, Holzgrabe U, Borsodi A (2003) Kappa-receptor selective binding of opioid ligands with a heterocyclic bicyclo[3.3.1]nonan-9-one structure. Acta Biol Hung 54 147-155... 

---