Synthesis, characterization and in vivo evaluation of [(62)Zn]-benzo-δ-sultam complex as a possible pet imaging agent

The development of a new tracer based on the cyclic sulfonamides (sultams) was investigated.

3-(Methoxy-phenyl-methyl)-1,6-dimethyl-1H benzo[c][1,2] thiazine 2,2-dioxide (benzo-δ-sultam) was synthesized and characterized by elemental analysis, FT-IR spectroscopy and single crystal X-ray structure determination. The prepared cyclic sulfonamide was labeled with non-commercial (62)Zn radioisotope for fast in vivo targeting and Coincidence imaging purposes (radiochemical purity 97 % ITLC, 96 % HPLC, specific activity 20-23 GBq/mmol). In vivo biodistribution of the final complex was investigated in Sprague Dawley(®) rats bearing fibro sarcoma tumor after 2, 4 and 8 h post injection and compared with free Zn(+2) cation.

Using instant paper chromatography method, the physicochemical properties of labeled compounds were found sufficiently stable in organic phases, e.g. a human serum, to be reliably used in bioapplications.

The complex exhibited a rapid as well as high tumor uptake (tumor to blood ratio 4.38 and tumor to muscle ratio 9.63) resulting in an efficient tumor targeting agent.