Synthesis and selective antitubercular and antimicrobial inhibitory activity of 1-acetyl-3,5-diphenyl-4,5-dihydro-(1H)-pyrazole derivatives

The new compounds 1-aryl-3-{1-phenyl-3-[p-(methylthio)phenyl]pyrazol-4-yl}-2-propen-1-ones 2a-1 were prepared by the condensation of 1-phenyl-3- [p-(methylthio)phenyl]-4-formylpyrazole 1 with different aryl ketones. Compounds 2a-1 in reaction with hydrazine hydrate yielded 3-aryl-5-{1-phenyl-3-[p-(methylthio)phenyl]pyrazol-4-yl}-4,5-dihydro-(1H)-pyrazoles 3a-1 and in the presence of hydrazine hydrate in glacial acetic acid gave 1-acetyl-3-aryl-5-{1-phenyl-3-[p-(methylthio)phenyl]pyrazol-4-yl}-4,5-dihydro-(1H)-pyrazoles 4a-1. These compounds were tested in vitro for their antitubercular and antimicrobial activities. The in vitro antimycobacterial activity of the newly synthesized compounds was investigated against Mycobacterium tuberculosis H37RV (ATCC 27294) in BACTEC 12B medium using the ALAMAR radiometric system. The antimicrobial in vitro activity was tested against Bacillus coccous, Bacillus subtilis, Escherichia coli, Proteus vulgaris and antifungal activity against Aspergillus niger. The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, H-1 NMR and mass spectral data.