Article Synthesis, in Vitro Biological Evaluation, and Oxidative Transformation of New Flavonol Derivatives: The Possible Role of the Phenyl-N,N- Dimethylamino Group Peter Szabados-Furjesi 1, David Pajtas 2, Aliz Barta 2, Evelin Csepanyi 1, Attila Kiss-Szikszai 3, Arpad Tosaki 4 and Istvan Bak 1,* 1 Department of Bioanalytical Chemistry, Faculty of Pharmacy, University of Debrecen, Debrecen H-4032, Hungary;
[email protected] (P.S.-F.);
[email protected] (E.C.) 2 Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen H- 4032, Hungary;
[email protected] (D.P.);
[email protected] (A.B.) 3 Department of Organic Chemistry, Faculty of Science and Technology, University of Debrecen, Debrecen Debrecen H-4032, Hungary;
[email protected] 4 Department of Pharmacology, Faculty of Pharmacy, University of Debrecen, Debrecen H-4032, Hungary;
[email protected] * Correspondence:
[email protected]; Tel./Fax: 00-36-52-255-586 Academic Editor: Luciano Saso Received: 13 November 2018; Accepted: 29 November 2018; Published: 30 November 2018 Abstract: Six new flavonols (6a–f) were synthesized with Claisen–Schmidt and Suzuki reactions and they were fully characterized by spectroscopic methods. In order to evaluate their antioxidant activities, their oxygen radical absorption capacity and ferric reducing antioxidant power were measured, along with their free radical scavenging activity against 2,2’-azino-bis(3- ethylbenzothiazoline-6-sulphonic acid) and 2,2-diphenyl-1-picrylhydrazylradicals. In addition, their cytotoxicity on H9c2 cardiomyoblast cells was also assessed by a 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide assay.