Preparation of 5-[ 131 I]iodotubercidin for the detection of adenosine kinase

5-Iodotubercidin is a prototype adenosine kinase (AK) inhibitor with potent anti-seizure activity in rodent epilepsy models. Using the chloramine-T method for radioiodination of tubercidin with 131 I, we prepared no-carrier-added 5-[ 131 I]iodotubercidin (5-[ 131 I]IT) in a radiochemical yield of 61 ± 13% and with a radiochemical purity of > 99% (molar activity = 10–40 GBq/µmol). In vitro competition and saturation experiments demonstrated specific binding of 5-[ 131 I]IT in rodent brain slices ( K D ~ 31 nM), but ex vivo autoradiography revealed its accumulation in cerebral vessels. We conclude that 5-[ 131 I]IT could be a useful tool for the detection and quantification of AK in in vitro studies.