Synthesis, characterization, and antioxidant activity of quercetin-based Schiff bases
No Thumbnail Available
Date
2024
Journal Title
Journal ISSN
Volume Title
Publisher
University of Oum El Bouaghi
Abstract
This work was carried out in the pedagogic laboratories of the Faculty of Exact Sciences and Natural and Life Sciences of Larbi Ben M'Hidi University, Oum El Bouaghi. We were able to synthesize biologically active organic compounds.
Initially, we were interested in the synthesis of three Schiff bases HA1, HA2, and HA3 of various structures from an aromatic amine or aliphatic/aromatic hydrazine, reacting with a common compound "quercetin". The first imine product being HA1: (4E)-4-(4-bromophenylimino)-2-(3,4-dihydroxyphenyl)-4H-chromene-3,5,7-triol resulting from the addition of 3-bromoaniline to quercetin. The second one is an azine with two imine functional groups; HA2: (4E,4'E)-4,4'-(hydrazine-1,2-diylidene)bis(2-(3,4-dihydroxyphenyl)-4H-chromene-3,5,7-triol) resulting from the equimolar the condensation of quercetin and hydrazine.The last structure represents a hydrazone Schiff base which is HA3: (4E)-4-(2-(2,4-dinitrophenyl)hydrazono)-2-(3,4-dihydroxyphenyl)-4H-chromene-3,5,7-triol obtained following the reaction of 2,4-dinitrophenylhydrazine with quercetin. The products were isolated in the solid state. Their structures were characterized by UV-visible and IR as well as by measuring their melting points and frontal ratios.
The evaluation of antioxidant activities of the synthesized imines HA1, and HA2 through the DPPH scavenging mechanism, and by graphical determination of the 50% inhibitory concentration compared to the ascorbic acid standard. The HA1 Schiff base showed the best antioxidant potential with an IC50=80.0g/mL and an excellent DPPH free radical inhibition percentage of 95.7% versus 98.4% for ascorbic acid. These results are in perfect agreement with the predicted structures and thus confirm a strong structure-activity relationship
Description
Keywords
Imine; Antioxidant activity; Schiff Base