Dichloro-4-quinolinol-3-carboxylic acid: Synthesis and antioxidant abilities to scavenge radicals and to protect methyl linoleate and DNA

5,7-, 5,8-, 6,8-, 7,8-Dichloro-4-quinolinol-3-carboxylic acid (5,7-, 5,8-, 6,8-, 7,8-DCQA) together with 7-chloro-4-quinolinol-3-carboxylic acid (7-CQA) and 4-quinolinol-3-carboxylic acid (QA) were synthesized to investigate the antioxidant properties. 5,7-DCQA exhibited the highest ability to scavenge 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS+.), 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and galvinoxyl radicals. 6,8-DCQA possessed the highest efficacy to protect methyl linoleate against 2,2′-azobis(2-amidinopropane)dihydrochloride (AAPH)-induced oxidation. 5,7-, 5,8-DCQA and QA were able to retard the β-carotene-bleaching in β-carotene-linoleic acid emulsion. In addition, 5,8- and 6,8-DCQA efficiently protected DNA against hydroxyl radical (.OH)-mediated oxidation, and 5,8-DCQA and 7-CQA were active to protect DNA against AAPH-induced oxidation. Furthermore, only 7-CQA can protect DNA against Cu2+/glutathione (GSH)-mediated oxidation. Dichloro-4-quinolinol-3-carboxylic acids were potent to be antiradical drugs, and were worthy to be researched pharmacologically.

4-Quinolinols were applied to trap ABTS+., DPPH and galvinoxyl radicals, to inhibit radical-induced oxidation of methyl linoleate, and to protect DNA against hydroxyl, peroxyl radicals, and Cu2+/glutathione-mediated oxidation.Figure optionsDownload as PowerPoint slide