Synthesis of some novel 3- (4-ethoxyphenyl) -5- (4-substituted) -4,5-dihydro-1H-pyrazole derivatives as potent antioxidant agents

Abstract

Pyrazolines are the most useful heterocyclic moiety in Pharmaceutical and Chemical fields and as the most potential molecules for the design of new chemical entities. Nitrogen-containing heterocyclic compounds, pyrazolines and their derivatives showed a variety of pharmacological activities, including antioxidant properties. In the present study, eleven novel ethoxylated pyrazoline derivatives were synthesized by condensing chalcones with electron releasing ethoxy group at one end and different electron-donating, electron-withdrawing groups in another end with hydrazine hydrate and alcohol. The compounds synthesized were structural elucidated by their spectroscopic studies. All the compounds synthesized were evaluated for their in vitro antioxidant potential by 2,2’-diphenyl-1-picrylhydrazyl (DPPH) and hydrogen peroxide free radical scavenging assay methods. Some of these molecules possess moderate to good antioxidant activity when compared to standard ascorbic acid. The compound with methoxy group (EH2) exhibits potent antioxidant activity with IC₅₀ value of 9.02 and 9.44µg/ml in DPPH and hydrogen peroxide assay methods respectively and the compound with hydroxy group (EH9) also showed potent antioxidant activity with IC₅₀ value of 12.41 and 14.56µg/ml in DPPH and hydrogen peroxide free radical scavenging assay methods respectively when compared to standard. The compounds containing electron-donating substituents were found to be good antioxidants when compared to standard ascorbic acid.