SYNTHESIS AND CHARACTERIZATION OF VARIOUS ACETYL PYRAZOLINE (5a-b)

Abstract

Background: Pyrazolines, a significant class of nitrogen-containing heterocycles, are widely recognized for their diverse pharmacological properties. N-acetylated pyrazolines, in particular, have attracted interest due to their potential antioxidant and antimicrobial activities. Materials and Methods: Chalcones were synthesized via Claisen–Schmidt condensation of acetophenone with substituted benzaldehydes, followed by oxidative cyclization using hydrazine hydrate to yield pyrazolines. Subsequent acetylation with glacial acetic acid under reflux afforded acetyl pyrazoline derivatives (5a–b). The compounds were characterized through UV/Vis, IR spectroscopy, and melting point analysis. Antioxidant potential was evaluated using DPPH radical scavenging and ferric reducing power assays, while antimicrobial activity was determined by agar disk diffusion method. Results: Compound 5a exhibited superior free radical scavenging at lower concentrations, reaching 70.59% at 1 mg/ml, whereas compound 5b showed moderate activity at low concentrations but comparable efficacy at higher doses. In FRAP assay, 5b demonstrated greater reducing power (42.8%) than 5a (33.5%). Conclusion: The synthesized N-acetyl pyrazolines (5a–b) exhibit promising antioxidant properties with structural variations influencing activity, supporting their potential as pharmacologically valuable scaffolds.