Synthesis and antidepressant activities of some 1,3,5-triphenyl-2-pyrazolines

Ten new 1,3,5-triphenyl-2-pyrazoline derivatives were synthesized by reacting 1,3-diphenyl-2-propen-1-one with phenylhydrazine. The chemical structures of the compounds were proved by means of their UV, IR, H-1-NMR spectroscopic data and elementary analyses. The antidepressant activities of these compounds were screened by the Porsolt behavioral despair test. 1-Phenyl-3-(4-methylphenyl)-5-(3,4-dimethoxyphenyl)-2-pyrazoline and 1-phenyl-3-(4-methylphenyl)-5-(2-chloro-3,4-dimethoxyphenyl)-2-prazoline showed significant antidepressant activity compared with clomipramine and tranylcypromine. A methyl substituent on the phenyl ring at position 3 of the pyrazoline ring enhances the antidepressant activity; the replacement of this methyl group by chloro or bromo substituents decreases the activity. In addition, introduction of a chloro substituent to the phenyl at the position 5 decreases the antidepressant activity.