title: Coumestan inhibits radical-induced oxidation of DNA: is hydroxyl a necessary functional group?
abstract: Coumestan is a natural tetracycle with a C═C bond shared by a coumarin moiety and a benzofuran moiety. In addition to the function of the hydroxyl group on the antioxidant activity of coumestan, it is worth exploring the influence of the oxygen-abundant scaffold on the antioxidant activity as well. In this work, seven coumestans containing electron-withdrawing and electron-donating groups were synthesized to evaluate the abilities to trap 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS(•+)), 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH), and galvinoxyl radical, respectively, and to inhibit the oxidations of DNA mediated by (•)OH, Cu(2+)/glutathione (GSH), and 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH), respectively. It was found that all of the coumestans used herein can quench the aforementioned radicals and can inhibit (•)OH-, Cu(2+)/GSH-, and AAPH-induced oxidations of DNA. In particular, substituent-free coumestan exhibits higher ability to quench DPPH and to inhibit AAPH-induced oxidation of DNA than Trolox. In addition, nonsubstituted coumestan shows a similar ability to inhibit (•)OH- and Cu(2+)/GSH-induced oxidations of DNA relative to that of Trolox. The antioxidant effectiveness of the coumestan can be attributed to the lactone in the coumarin moiety and, therefore, a hydroxyl group may not be a necessary functional group for coumestan to be an antioxidant.
authors.affiliation: Department of Organic Chemistry, College of Chemistry, Jilin University , Changchun 130021, China.
authors.forename: Gao-Lei
authors.initials: GL
authors.lastname: Xi
authors.forename: Zai-Qun
authors.initials: ZQ
authors.lastname: Liu
mesh_terms: D000578:Amidines / Q000737:chemistry; D000975:Antioxidants / Q000737:chemistry; D001572:Benzofurans / Q000737:chemistry; D001713:Biphenyl Compounds / Q000737:chemistry; D003374:Coumarins / Q000737:chemistry*; D004247:DNA / Q000737:chemistry*; D005978:Glutathione / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D010084:Oxidation-Reduction; D010851:Picrates / Q000737:chemistry
chemical_list: D000578:Amidines; D000975:Antioxidants; D001572:Benzofurans; D001713:Biphenyl Compounds; D003374:Coumarins; D010851:Picrates; D017665:Hydroxyl Radical; C046728:2,2'-azobis(2-amidinopropane); D004247:DNA; C030123:coumarin; C004931:1,1-diphenyl-2-picrylhydrazyl; D005978:Glutathione; C105430:benzofuran; C505898:coumestan