Cationic technetium and rhenium complexes with pendant carbohydrates

Three carbohydrate conjugated dipicolylamine chelators, 2-bis(2-pyridinylmethyl)amino)ethyl 1-deoxy-1-thio-β-D-glucopyranoside (L1), 2-bis(2-pyridinylmethyl)amino)ethyl-β-D-glucopyranoside (L2), and 2-bis(2-pyridinylmethyl)amino)carboxamide-N-(2-amino-2-deoxy-D-glucopyranose) (L3) were complexed to the [M(CO)3]+ core (M=Tc, Re) and the properties of the resulting complexes were investigated. Synthesis and characterization of the chelator 2-bis(2-pyridinylmethyl)amino)ethyl 1-deoxy-1-thio-β-D-glucopyranoside (L1) and the corresponding Re complex are reported. All chelators were radiolabeled in high yield with [99mTc(CO)3(H2O)3]+ (>98%) and [186Re(CO)3(H2O)3]+ (>80%). The chelators and Re-complexes were determined to not be substrates for the glucose metabolism enzyme hexokinase. However, the biodistribution of each of the 99mTc complexes demonstrated fast clearance from most background tissue, including >75% clearance of the activity in the kidneys and the liver within 2 h post-injection.