Design synthesis and structure–activity relationship of 5-substituted (tetrahydronaphthalen-2yl)methyl with N-phenyl-N-(piperidin-2-yl)propionamide derivatives as opioid ligands. Issue 2 (15th January 2016) - Deekonda, Srinivas
Graphical abstract: Abstract: Here, we report the design, synthesis and structure activity relationship of novel small molecule opioid ligands based on 5-amino substituted (tetrahydronaphthalen-2-yl)methyl moiety with N -phenyl- N -(piperidin-2-yl)propionamide derivatives. We synthesized various molecules including amino, amide and hydroxy substitution on the 5th position of the (tetrahydronaphthalen-2-yl)methyl moiety. In our further designs we replaced the (tetrahydronaphthalen-2-yl)methyl moiety with benzyl and phenethyl moiety. These N -phenyl- N -(piperidin-2-yl)propionamide analogues showed moderate to good binding affinities (850–4 nM) and were selective towards the μ opioid receptor over the δ opioid receptors. From the structure activity relationship studies, we found that a hydroxyl substitution at the 5th position of (tetrahydronapthalen-2yl)methyl group, ligands19 and20, showed excellent binding affinities 4 and 5 nM, respectively, and 1000 fold selectivity towards the μ opioid relative to the delta opioid receptor. The ligand19 showed potent agonist activities 75 ± 21 nM, and 190 ± 42 nM in the GPI and MVD assays. Surprisingly the fluoro analogue20 showed good agonist activities in MVD assays 170 ± 42 nM, in contrast to its binding affinity results.