Biological evaluation of two iodine-123-labeled D-glucose acetals prepared as glucose transporter radioligands

Two iodinated acetals of D-glucose, 4,6-(R)-O-(2'-iodoethylidene)-alpha, beta-D-glucose (1) and 4,6-(R)-O-(4'-iodobenzylidene)-alpha, beta-D-glucose (2), were prepared and their potential as suitable SPECT radioligands for imaging of glucose transporters was studied. Both are analogs of acetal D-glucose derivatives, which are known to bind to the exofacial sites of the glucose transport protein (GluT). To assess whether iodinated acetals 1 and 2 interacted with the glucose transporter, they were tested in vitro in human erythrocytes (GluT1) and neonatal rat cardiomyocytes (GluT4). The results indicated that 1 and 2 had a very low affinity for the glucose transporter and probably accumulated in cells. Study of their tissue distribution was carried out in the mouse in vivo: Both compounds showed fast tissue clearance with preferential renal elimination. It is concluded that iodinated acetals of D-glucose 1 and 2 are not suitable for GluT targeting in vivo.