Based on excellent experiment results of 99mTcO-MPBDA-CI, two new ligands MPTDA and MPDAA are synthesized. Then series of 99mTcO3+ complexes are prepared through adding different halide anions, followed by tests of physical chemistry qualities and biodistribution experiments. And results of these experiments show that complexes formed with MPTDA and MPDAA have better lipophilicity than those formed with MPBDA, still maintain the good brain retention ability of this type of compounds, but radioactivity uptake in blood is higher than that of 99mTcO-MPBDA and ratios of brain/blood are reduced. Obvious affections are fetched out on brain uptake and retention if fluoride, bromide or iodide anions are added. Results of experiments can be explained in reason with theoretic computation. It is confirmed that 99mTcO-MPBDA-CI has potential to develop a new type of brain imaging agent considering integrated factors such as brain uptake, retention and toxicity.
The structureaffinity correlations of a series of benzamides for dopamine D 2 receptor imaging agents have been studied with SYBYL 6.4 software on SGI O 2 workstation.The results of conformational analysis and PM3 calculation have demonstrated that the coplanar effect of benzamides is one of the most important requirements for activity in vitro.The aromatic substituent in the 2 position is the main factor which influences the coplanar arrangement of pseudring (B) involving the amide moiety and the methoxy group relative to the aromatic ring,while the influences of other factors on this side such as the aromatic substituents in the 3 and 5 positions and the conformation of side chain may be neglected.The conclusion may be useful in understanding the interaction of D 2 receptorligand and designing new D 2 receptor ligands.
