Synthesis and biodistribution of two novel 99mTc( SNN/S) "3+1" mixed ligand complexes as potential brain perfusion agents.

Two novel [99mTc] [ SNN/S] "3+1" mixed ligand complexes, where L3H2= o-methylthio-glycinanilide (A) or N-(1-methylthio-phenyl)-ethylenediamine (B) and L1H= isopropanethiol, were synthesized using stannous chloride as reductant and glucoheptonate as transfer ligand. The identifications of [99mTc]-A and [99mTc]-B were established by thin layer chromatography. The radiochemical purity of both complexes was over 90%. The initial biodistribution study in mice demonstrated that both complexes can penetrate the intact blood-brain barrier and exhibit retention in mice brain. The brain uptake (%ID/g) values of [99mTc]-A were 1.68, 1.23, 1.24 and of [99mTc]-B were 1.76, 1.08, 0.90 at 2, 30 and 60 min i.v. postinjection, respectively.