Previously, we reported the thiourea antagonists 2a and 2b as potent and high affinity TRPV1 antagonists. For further optimization of the lead compounds, a series of their amide and alpha-substituted amide surrogates were investigated and novel chiral N-(2-benzyl-3-pivaloyloxypropyl) 2-[4-(methylsulfonylamino)phenyl]propionamide analogues were characterized as potent and stereospecific rTRPV1 antagonists. In particular, compounds 72 and 73 displayed high binding affinities, with K-i values of 4.12 and 1.83 nM and potent antagonism with Ki values of 0.58 and 5.2 nM, respectively, in rTRPV1/CHO cells. These values are comparable or more potent than those of 5-iodoRTX under the same assay conditions. A distinctive binding model that includes two hydrophobic pockets is proposed for this series of compounds based on docking studies of 57 and 72 with a homology model of the TM3/4 region of TRPV1.
α-Methylated simplified resiniferatoxin (sRTX) thiourea analogues as potent and stereospecific TRPV1 antagonists
摘要:
A series of alpha-methylated analogues of the potent sRTX thiourea antagonists were investigated as rTRPV1 ligands in order to examine the effect of alpha-methylation on receptor activity. The SAR analysis indicated that activity was stereospecific with the (R)-configuration of the newly formed chiral center providing high binding affinity and potent antagonism while the configuration of the C-region was not significant. (C) 2014 Elsevier Ltd. All rights reserved.