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In order to replace thiourea group with the more drug-like moiety for 1,3-dibenzylthioureas having TRPV1 antagonist activity, we introduced a set of functional groups between the two aromatic rings based on bioisosteric replacement. The synthesized bioisosteres of 1,3-dibenzylthioureas were tested for their antagonist activities on TRPV1 by 45 Ca 2+ -influx assay using neonatal rat cultured spinal sensory neurons. Among the tested 14 kinds of bioisosters, 2-methylacrylamide group was the best candidate to replace thiourea group. Compound 7c , 2-methylacrylamide analog of ATC-120, showed as potent as ATC-120 in its antagonist activity. In addition, 2-methylacrylamide analog 7e having vinyl moiety showed the most potent activity with 0.022 μM of IC 50 value, indicating that thiourea group of 1,3-dibenzylthioureas could be replaced to 2-methylacrylamide without loss of their potencies. [ABSTRACT FROM AUTHOR]

Abstract: In searching for opportunities to exploit the benefits of silicon in TRPV1 research, we tried to investigate the pharmacological effects of sila-substitution (C/Si exchange) of tert-butyl group in the MK-056 series. Compound 13a, with a 4-positioned trimethylsilanyl group on the B ring in place of tert-butyl group, exhibited the most potent antagonist activity with IC50 values of 0.15μM, which is almost equipotent with that of MK-056. This is the first example that tert-butyl group on MK-056 series can be replaced to the other substituent without loss of activity. [Copyright &y& Elsevier]