Development of 5-(Aryl)-3-phenyl-1H-pyrazole Derivatives as Potent Antimicrobial Compounds

B. Nagendra Chowdary1, M. Umashankara2, B. Dinesh3, K. Girish4,* and A. Ramesha Baba1,*

1Post Graduate Department of Chemistry, Maharani’s Science College for Women, Mysore-570 005, India

2Department of Studies in Chemistry, Karnataka State Open University, Mukthagangothri, Mysore-570006, India

3Molecular Biophysics Unit, Indian Institute of Science, Bangalore-560012, India

4Post Graduate Department of Microbiology, Maharani’s Science College for Women, Mysore-570005, India

*Corresponding authors: E-mail: girishk77@yahoo.com; arbaba71@gmail.com

Abstract

A series of 16 chalcone compounds were synthesized by Claisen-Schmidt condensation of various aldehydes with acetophenone using KOH as a base in ethanol. The reaction affords the desired products in good yields. Then all the 16 compounds were converted into pyrazoles by treating with hydrazine hydrate in ethanol under reflux condition. Both chalcones and pyrazoles were screened for their in vitro antibacterial (Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa) and antifungal (Aspergillus flavus, Chrysosporium keratinophilum and Candida albicans) activity. Biological activities of these compounds were compared with those of commercially available antibiotic ampicillin and antifungal agent miconazole. Pyrazoles were found to be most active and effective than corresponding chalcones for antimicrobial activity. Out of the 7 pyrazole compounds tested for antibacterial and antifungal activity, 5 compounds, 4h, 4j, 4l, 4m and 4n are turned out to be potent antimicrobial agents. Therefore these derivatives could serve as a highly promising molecules for further development.

Keywords

Antibacterial, Antifungal, Heterocyclic and Substituted pyrazoles, Chalcone.

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