Abstract

Pyrazole derivatives (I-VII) were prepared in good yields using aldol condensation followed by cyclization and were characterized by elemental analysis, IR and ¹H NMR spectroscopy. In vitro antileishmanial activity test was conducted using Alamar blue reduction method. The test revealed that the synthesized compounds (except compound IIb) exhibit better antileishmanial activity than the standard drug miltefosine and lower antileishmanial activity (except compounds III and IIIb) compared to the standard drug amphotericin B deoxycholate. Compound IIIb, phenyl pyrazoline with propanoyl side chain, 1-(3-phenyl-5-(1-phenyl-3-p-tolyl-1H-pyrazol-4-yl)-4,5-dihydropyrazol-1-yl)propan-1-one, was found to be the most active (IC₅₀= 0.0112 µgml^-1) than the standards miltefosine (IC₅₀ = 0.3±0.04 µgml^-1) and amphotericin B deoxycholate (IC₅₀ = 0.2±0.02 µgml^-1) for Leishmania donovani. Compound III was found to be the most active (IC₅₀ = 0.28±0.03 µgml^-1) and has comparable antileishmanial activity to the standard miltefosine (IC₅₀ = 0.3±0.04 µgml^-1) and amphotericin B deoxycholate (IC₅₀ = 0.2±0.02 µgml^-1) on Leishmania aethiopica amastigote.

Key words: Pyrazole derivative, biological screening, antileishmanial agent.