Antileishmanial and Antibacterial Activity of a New Pyrazole Derivative Designated 4‐[2‐(1‐(Ethylamino)‐2‐methyl‐ propyl)phenyl]‐3‐(4‐methyphenyl)‐1‐phenylpyrazole

Here, we report for the first time the synthesis and the antileishmanial activity of a new pyrazole derivative, namely 4‐[2‐(1‐(ethylamino)‐2‐methylpropyl)phenyl]‐3‐(4‐methyphenyl)‐1‐phenylpyrazole). Micromolar concentrations of this compound were found to inhibit the in vitro multiplication of Leishmania tropica , Leishmania major , and Leishmania infantum , three species causing different forms of leishmaniasis. Furthermore, the 50% inhibitory concentration (IC 50 ) values for the compound are only slightly higher than those of amphotericin B, one of the most active antileishmanial agents used as a satisfactory substitute in cases not responding to pentostam. The IC 50 values after 48 h for L. tropica, L. major , and L. infantum promastigote growth were 0.48 μg/mL, 0.63 μg/mL and 0.40 μg/mL, respectively for the compound, while they were 0.23 μg/mL, 0.29 μg/mL and 0.24 μg/mL, respectively for amphotericin B. We also tested this compound for its antibacterial activity against several bacteria. The strongest antibacterial activity was observed against Entrococcus feacalis and Staphylococcus aureus with a minimal inhibitory concentration (MIC) of 60 μg/mL.