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An Improved Protocol for the Synthesis of Chalcones Containing Pyrazole with Potential Antimicrobial and Antioxidant Activity

[ Vol. 14 , Issue. 1 ]

Author(s):

Simpal Kumari*, Sarvesh K. Paliwal and Rajani Chauhan   Pages 39 - 47 ( 9 )

Abstract:


Background: Chalcones holding arylic substitutions and pyrazolic chalcones were reported as potent antimicrobial and antioxidant agents. Prompted by the literature, it was considered of interest in the present work to develop the bioactive materials incorporating five, and six-membered ring heterocycles in a single molecular framework with above molecules.

Methods: Synthesis of chalcone derivatives derived from condensation of 2-(3,5-dimethyl-pyrazol-1- yl)-1-phenyl-ethanone and aldehydes has been discussed. Sodium hydride was employed as catalyst to facilitate the reaction which proved to be a worthy catalyst over NaOH and KOH. This protocol offers advantages such as easy workup, shorter reaction time and promising yield for the synthesis of chalcones. Further, another aromatic ring was installed to the chalcones to obtain pyrimidine, isoxazole, and pyrazole derivatives. The structures of the prepared compounds were confirmed by FT-IR, 1H NMR, 13CNMR spectroscopy, Mass spectrometry and elemental analysis. The biological activity of the compounds against four bacterial strains namely Bacillus subtilis, Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli and three fungal strains have been evaluated.

Results: An improved process for biologically useful chalcone derivatives has been discussed providing overall good yield. The newly synthesized compounds were screened for in vitro antioxidant and antimicrobial activity. Based on the preliminary results, compounds 5c, 6c, 6d in this series showed significant activity against tested bacterial strains. Compounds 6b, 6c, 6d and 7b showed potent inhibitory activity against fungal growth. Among them, compound 6c displayed the most potent activity against Candida parapsilosis, Candida tropicalis, Candida albicans, which was comparable with standard drug fluconazole.

Conclusion: Synthesis, characterization and biological evaluation of new heterocyclic pyrazole chalcones has been described. The method of preparation of these compounds is very straightforward and free of tedious work up as well quite time saving. All the compounds have shown moderate to good inhibitory activity against B. subtilis and exhibited mild to moderate antibacterial activities against the other tested organisms.

Keywords:

Pyrazole, chalcone, Claisen Schmidt reaction, pyrimidine, antimicrobial, antioxidant.

Affiliation:

Department of Pharmacy, Banasthali University, Banasthali University, Vanasthali, Rajasthan-304022, Department of Pharmacy, Banasthali University, Banasthali University, Vanasthali, Rajasthan-304022, Department of Pharmacy, Banasthali University, Banasthali University, Vanasthali, Rajasthan-304022

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