6-Alkoxymethyl-3-hydroxy-4H-pyranones: potential ligands for cell-labelling with indium.

We have identified ligands for cell labelling with indium-111: 3-hydroxy-6-propoxymethyl-4H-pyran-4-one and 6-butoxymethyl-3-hydroxy-4H-pyran-4-one. The leucocyte labelling efficiencies of (111)In complexes of these ligands were higher and label stabilities were found to be similar compared with those obtained using (111)In-tropolonate. High labelling efficiencies of neutrophils and lymphocytes were achieved with (111)In complexes of pyranones. Tropolone was found to have a greater inhibitory effect on metalloenzymes and to cause greater impairment of platelet function than 3-hydroxy-6-propoxymethyl-4H-pyran-4-one. Thus 6-alkoxymethyl-3-hydroxy-4H-pyran-4-ones may have advantages over current ligands used in cell labelling with (111)In.