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 (IC50) 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 IC50 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. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA.