Ultrasound-Promoted Synthesis, Structural Characterization and in vitro Antimicrobial Activity of New 5-Aryl-3-(2-hydroxyphenyl)-4,5-dihydro-1H-pyrazole-1-carboximidamides

Abstract

This work aims the synthesis of amidino pyrazolines by the cyclocondensation reaction between 3-(hetero)aryl-1-(2-hydroxyphenyl)enones and aminoguanidine hydrochloride under sonochemical conditions. Thirteen new compounds were synthesized in 15-83% of yield after sonication for 30 min without purification by chromatography. Furthermore, antimicrobial activities of the synthesized compounds were investigated by in vitro minimum inhibitory concentration (MIC) in a panel of four bacterial strains and four Candida yeasts. As result, the 5-(4-bromophenyl)-3-(2-hydroxyphenyl)-4,5-dihydro-1H-pyrazole-1-carboximidamide hydrochloride was identified as the most active against gram-positive S. aureus and E. faecalis with MIC of 7.8 µg mL−1, similar to the value showed by chloramphenicol, which was used as standard.