<i>cis</i>-4-Amino-<scp>l</scp>-proline Residue As a Scaffold for the Synthesis of Cyclic and Linear Endomorphin-2 Analogues: Part 2
作者:Adriano Mollica、Francesco Pinnen、Azzurra Stefanucci、Luisa Mannina、Anatoly P. Sobolev、Gino Lucente、Peg Davis、Josephine Lai、Shou-Wu Ma、Frank Porreca、Victor J. Hruby
DOI:10.1021/jm300947s
日期:2012.10.11
Recently, we reported synthesis and activity of a constrained cyclic analogue of endomorphin-2 (EM-2: Tyr-Pro-Phe-Phe-NH2) and related linear models containing the cis-4-amino-L-proline (cAmp) in place of native Pro(2). In the present article, the adopted rationale is the possible modulation of the receptor affinity of the cAmp containing EM-2 analogues by assigning a different stereochemistry to the Phe(3) and Phe(4) residues present in the ring. Thus, eight more analogues with different absolute configuration at the chiral center of the aromatic residues in positions 3 and 4 have been synthesized and their opioid activity examined. The stereochemical change at the alpha-carbon atoms leads to a meaningful enhancement of the affinity and activity toward mu opioid receptors with respect to the prototype compound 9: e.g., 9a, K-i(mu) = 63 nM, GPI (IC50) = 480 nM; 9b, K-i(mu) = 38 nM, GPI (IC50) = 330 nM.