Synthesis and anti-staphylococcal activity of new 4-diazopyrazole derivatives

Several new 4-diazopyrazole derivatives 6a–g and 9a–c were obtained by the reaction of 1-(R-substituted-phenyl)-3-(1,3-dimethyl-1H-pyrazol-5-yl)ureas 5a–g and N-(1,3-dimethyl-1H-pyrazol-5-yl)-2-(R-substituted-phenyl)acetamides 8a–c respectively with a sevenfold excess of nitrous acid in acetic acid solution. The compounds were assayed for their activity against the Staphylococcus aureus reference strains ATCC 25923, ATCC 29213 and ATCC 6538, as well as six veterinary strains. The best anti-staphylococcal profile was showed by [(R-substituted-phenyl)acetyl](4-diazonio-1,3-dimethyl-1H-pyrazol-5-yl)azanides 9a,c. Compound 9c was also able at 3.1 μg mL−1 to inhibit of 45.7% the biofilm formation of the strains S. aureus ATCC 29213.

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► A series of 4-diazopyrazoles were synthesized.
► Synthesized compounds were evaluated against Staphylococcus aureus strains.
► The best anti staphylococcus profile was showed by compounds 9a,c.
► Compounds 9a,c were able to inhibit the biofilm formation of S. aureus.