Antipyrine congeners as antidepressant agents

1-(N-Antipyrinylglycyl)-3-arylideneamino)-2-thiobarbituric acids (III) were synthesized from 1-arylidene-4-(N-antipyrinyl glycyl)-3-thiosemicarbazones (II). Compounds II in turn were prepared from 4-amino antipyrine. Compounds III were finally converted into 1-(N-antipyrinylglycyl)-3-[(3'-chloro-4-aryl)azitidinyl]-2-t hiobarbituric acids (IV). 4-Aminoantipyrine was also treated with different N-protected amino acids in the presence of N,N'-dicyclohexylcarbodiimide to yield N-(antipyrinylcarbamoyl) substituted alkyl benzamides (V); their debenzoylation yielded 2-(amino-N-antipyrinyl) substituted acetamides (VI). The compounds were screened for their antidepressant activity. Compounds IIId, Va and Vb exhibited activity better than imipramine with less toxicity (ALD50 > 1000 mg/kg).