TITLE:
Synthesis, Characterization, Antimicrobial, and Antioxidant Activity of Novel Heterocyclic Compounds Containing a Pyrazolone Core Moiety
AUTHORS:
Mohamed Ali El Sekily, Sohila Hasan Mancy, Nagwa Mohamed Mahrous Hamada
KEYWORDS:
Pyrazolone, Heterocyclic, Antimicrobial, Antioxidant, Synthesis, Biological Testing
JOURNAL NAME:
International Journal of Organic Chemistry,
Vol.16 No.2,
June
29,
2026
ABSTRACT: Background: Polycyclic heterocyclic compounds are highly relevant in medicinal chemistry because of their structural diversity and broad spectrum of biological activity. One of these is pyrazolone-based systems, which have become multifunctional scaffolds with considerable pharmacological potential. Objective: The objective of the current project was to develop, prepare, and test a set of new heterocyclic compounds containing a pyrazolone framework, with a focus on targeting antimicrobial and antioxidant activities. Methods: Pyrazole carboxaldehyde precursor was previously obtained from ascorbic acid. The precursor was reacted through numerous condensation, cyclization, and multi-component reactions to obtain structurally diverse heterocyclic derivatives. Elemental analysis, infrared spectroscopy, and proton nuclear magnetic resonance spectroscopy were all used to completely characterize the synthesized compounds. The agar well-diffusion technique was used to determine the antimicrobial activity against standard Gram-positive and Gram-negative bacterial strains, and the fungal strain of Candida albicans. Compare-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay was used to assess the antioxidant activity, and the IC50 was determined to compare the relative antioxidant activity. Results: The biological screening indicated that the synthesized compounds were selectively antifungal against Candida albicans, with minimal or no antibacterial activity. Several derivatives showed moderate to strong antioxidant activity depending on concentration. The structure-activity relationship analysis showed that heterocyclic fusion motifs and the inclusion of electron-donating substituents significantly influenced the modulation of biological activity. Conclusion: The results demonstrate that the pyrazolone scaffold is an attractive platform on which novel heterocyclic compounds with potential as antifungal and antioxidant agents can be developed.