Synthesis and Dopamine Receptor Modulating Activity of Novel Peptidomimetics of <scp>l</scp>-Prolyl-<scp>l</scp>-leucyl-glycinamide Featuring α,α-Disubstituted Amino Acids
作者:Margaret C. Evans、Ashish Pradhan、Shankar Venkatraman、William H. Ojala、William B. Gleason、Ram K. Mishra、Rodney L. Johnson
DOI:10.1021/jm980656r
日期:1999.4.22
In the present study, L-prolyl-L-leucyl-glycinamide (1) peptidomimetics 3a-3d and 4a-4d were synthesized utilizing alpha,alpha-disubstituted amino acids. These analogues were designed to explore the conformational effects of constraints at the phi(3) and psi(3) torsion angles. Constrained conformations were verified by the use of X-ray crystallography and circular dichroism. The effects of Pro-Leu-Gly-NH2 analogues 3a-3d and 4a-4d on enhancing rotational behavior induced by apomorphine in the 6-hydroxydopamine-lesioned animal models of Parkinson's disease were studied. The ability of these peptidomimetics to increase the binding of agonist N-propylnorapomorphine (NPA) to the dopamine D-2 receptor was also examined. Extended analogue Pro-Leu-Deg-NH2 was the most active compound of this series. It was 10 times more potent and almost 2 times more effective than 1 in increasing apomorphine-induced rotations (56 +/- 15% at 1.0 mg/kg ip) and in enhancing [H-3]NPA specific binding (40%).