Title:An Improved Protocol for the Synthesis of Chalcones Containing Pyrazole with Potential Antimicrobial and Antioxidant Activity
VOLUME: 14 ISSUE: 1
Author(s):Simpal Kumari*, Sarvesh K. Paliwal and Rajani Chauhan
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
Keywords:Pyrazole, chalcone, Claisen Schmidt reaction, pyrimidine, antimicrobial, antioxidant.
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.
