Studies on Specific Inhibition of Benzodiazepine Receptor Binding by Some C-Benzoyl-1,2,3-triazole Derivatives

Certain new (1-15) or previously described (16-25) 1,2,3-triazole derivatives, characterized by a C-benzoyl substituent, were synthesized and tested for their ability to displace [H-3]flunitrazepam from bovine brain membrane. Compounds 11 a and ga, bearing neutral and lipophilic substituents (phenethyl and cyclohexyl, respectively) showed the higher activity. The 5-benzoyl isomer 11 b presented a lower activity, equivalent to that of the triazole acetic derivative 23, which is 4-benzyl substituted. Generally, the carboxymethyl radical in the 1-position of the triazole ring decreased the activity, probably because of intramolecular hydrogen bonding with the carbonyl function of the benzoyl substituent. The N-1 unsubstituted triazole derivatives 24 and 25 were ineffective; this result is in disagreement with our previous observations. Probably these molecules interact with the receptor site by a hydrogen bonding acceptor group and by a bulky and lipophilic portion or a hydrogen bonding donor function that is appropriately arranged.