Studies on Tc-99m complexes of functionalised propylene amine-oxime (PnAO)ligands

Three functionalised PnAO ligands, 3,3,9,9-tetramethyl-6-R-4, 8-diazaundeca ne-2, 10-dionedioxime (R= benzyl, p-nitrobenzyl and p-aminobenzyl) were syn thesized. Tc-99m complexes of these ligands were prepared at both tracer le vels and carrier added levels with (TcO4-)-Tc-99m and with (TcO4-)-Tc-99. C omplexation yields were estimated by thin layer chromatography, HPLC and so lvent extraction studies. The complexes were formed in high yields; the res ultant complexes were neutral, highly lipophilic(log P similar to 2.3-2.5) and elute as single peak on a re verse phase HPLC column. Complexes with al l the three ligands showed excellent stability over 24 h period of storage at room temperature. Biodistribution studies of the Tc-99m complexes of the benzyl and nitrobenzyl ligands in Wistar rats showed brain uptake of 1.2 /- 0.25% and 0.88 +/- 0.10% at 1 min post injection, respectively. The bloo d clearance was rapid in both the cases while the main excretory route,was the hepatobiliary system. The aminobenzyl derivative is a bifunctional liga nd which could be used for labeling antibodies and peptides with radiometal s.