337985-37-2Relevant academic research and scientific papers
Development of potent bifunctional endomorphin-2 analogues with mixed μ-/δ-opioid agonist and δ-opioid antagonist properties
Fujita, Yoshio,Tsuda, Yuko,Li, Tingyou,Motoyama, Takashi,Takahashi, Motohiro,Shimizu, Yoshiro,Yokoi, Toshio,Sasaki, Yusuke,Ambo, Akihiro,Kita, Atsuko,Jinsmaa, Yunden,Bryant, Sharon D.,Lazarus, Lawrence H.,Okada, Yoshio
, p. 3591 - 3599 (2007/10/03)
The C terminus of endomorphin-2 (EM-2) analogues (Tyr-Pro-Phe-NH-X) was modified with aromatic, heteroaromatic, or aliphatic groups (X = phenethyl,benzyl, phenyl, naphthyl, pyridyl, quinolyl, isoquinolyl, tert-butyl, cyclohexyl, or adamantyl; 3-18) to study their effect on opioid activity. Only 9 (1-naphthyl), 11 (5-quinolyl), 16 (cyclohexyl), and 18 (2-adamantyl) exhibited μ-opioid receptor affinity in the nanomolar range (Ki = 2.41-6.59 nM), which, however, was 3-to 10-fold less than the parent peptide. Replacement of Tyr1 by Dmt (2′,6′-dimethyl-L-tyrosine) (19-32) exerted profound effects: (i) acquisition of high μ-opioid receptor affinity (Ki = 0.11-0.52 nM) except 23 (Ph); (ii) presence of potent functional μ-opioid receptor agonism (IC50 1]EM-2), 27 (1-naphthyl), 29 (5-quinolyl), and 32 (5-isolquinolyl); (iii) association of weak δ-opioid antagonist activity (pA2 = 5.41-7.18) except 19 ([Dmt1]EM-2), 20 (H), 27 (1-naphthyl), and in particular 29 (5-quinolyl) with its potent δ-agonism (IC50 = 0.62 nM, pA2 = 5.88); (iv) production of antinociception after ic administration of 32 (5-isoquinolyl) in mice, a bioactivity absent in the corresponding Tyr1 analogue (14); and (v) preferential cis orientation (cis/trans = 3:2 to 7:3) at the Dmt-Pro amide bond, in contrast to the Tyr-Pro amide trans orientation (cis/trans = 1:2 to 1:3). Thus, [Dmt1]EM-2 analogues with hydrophobic C-terminal extensions provide model compounds with potent μ-opioid receptor bioactivity and dual functional agonism.
