benzofurans and 2-2--azobis(2-amidinopropane)

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.

Topics: Amidines; Antioxidants; Benzofurans; Biphenyl Compounds; Coumarins; DNA; Glutathione; Hydroxyl Radical; Oxidation-Reduction; Picrates

In this study the protective effect of phlorotannins, including phloroglucinol, eckol, dieckol, eckstolonol and triphloroethol A, isolated from brown algae Ecklonia cava was investigated against AAPH-induced oxidative stress toxicity in zebrafish embryos. Zebrafish embryos were exposed to AAPH and compared with other groups that were co-exposed with phlorotannins until 2-days post-fertilisation. All phlorotannins scavenged intracellular ROS and prevented lipid peroxidation and reduced AAPH-induced cell death in zebrafish embryos. Negative changes in morphological phenomena, such as pericardial oedema, yolk sac oedema, and growth retardation in zebrafish embryos exposed to AAPH were not observed in groups exposed to phlorotannins. These results clearly indicate that phlorotannins possess prominent antioxidant activity against AAPH-mediated toxicity and might be potential therapeutic agents for treating or preventing several diseases implicated with oxidative stress. This study provides a useful tool for examining the protective effect of antioxidants against AAPH-induced oxidative stress in an alternative in vivo model.

Topics: Amidines; Animals; Antioxidants; Benzofurans; Dioxins; Oxidative Stress; Phaeophyceae; Phloroglucinol; Protective Agents; Zebrafish

Ailanthoidol is a benzofuran-type neolignan containing an alcoholic and a phenolic hydroxyl groups and can be synthesized following the description in a previous report. In this work, its antioxidant effect was estimated in the experimental system of 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH)-induced oxidation of DNA. It was found that ailanthoidol can scavenge 1.5 radicals in protecting DNA against AAPH-induced oxidation. Moreover, a benzyl group was used to etherize the phenolic hydroxyl group of ailanthoidol, resulting in the formation of (E)-2-(4'-benzyloxy-3'-methoxyphenyl)-5-(3″-hydroxypropenyl)-7-methoxybenzofuran (BBF). However, BBF cannot protect DNA against AAPH-induced oxidation. This result demonstrated that the alcoholic hydroxyl group cannot play the antioxidative role in protecting DNA. Furthermore, a ferrocenyl group was used to substitute the alcoholic hydroxyl group, leading to the formation of (E)-1-ferrocenyl-3-(2'-(4″-hydroxy-3″-methoxyphenyl)-7'-methoxybenzofuran-5'-yl)prop-2-en-1-one (FBF). FBF can scavenge 2.0 radicals in protecting DNA against AAPH-induced oxidation. This result indicated that the antioxidant ability of FBF was higher than that of ailanthoidol. Finally, FBF and ailanthoidol were applied to trap 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS(+.)). It was found that FBF can trap 1.92 ABTS(+.), while ailanthoidol can trap 1.58 ABTS(+.). Therefore, the modification of ailanthoidol by ferrocenyl group enhanced radical-scavenging and antioxidative ability of ailanthoidol.

Topics: Amidines; Antioxidants; Benzofurans; DNA; Ferrous Compounds; Free Radical Scavengers; Kinetics; Metallocenes; Oxidation-Reduction

2,3-Dihydro-5-hydroxy-2,2-dipentyl-4,6-di-tert-butyl-benzofuran (BO-653) is a novel antioxidant synthesized by theoretical designing based on the previous experimental findings and consideration. The antioxidant activities of BO-653 against the oxidative modification of low-density lipoprotein (LDL) induced by free radicals were studied. BO-653 was consumed faster than endogenous alpha-tocopherol and inhibited the formation of lipid hydroperoxides, which was observed during the consumption of alpha-tocopherol. Doxyl stearic acids incorporated into LDL as spin probes competed with the antioxidants in scavenging radicals. It was found that the efficacy of radical scavenging by alpha-tocopherol became smaller as the radical went deeper into the interior of LDL particle, whereas that by BO-653 did not change. Ascorbic acid in the aqueous phase spared alpha-tocopherol efficiently during oxidation. On the other hand, the sparing effect of ascorbic acid for BO-653 was not remarkable, unlike that for alpha-tocopherol, which implied different locations of radicals derived from BO-653 and alpha-tocopherol within the LDL particle. It was concluded that BO-653 protected LDL from oxidative modification efficiently by scavenging peroxyl radicals and by reducing alpha-tocopheroxyl radicals and that this novel antioxidant might act as a potent inhibitor of development of atherosclerosis.

Topics: Amidines; Animals; Antioxidants; Apolipoproteins B; Arteriosclerosis; Ascorbic Acid; Azo Compounds; Benzofurans; Cyclic N-Oxides; Drug Design; Free Radical Scavengers; Humans; Kinetics; Lipid Peroxidation; Lipid Peroxides; Lipoproteins, LDL; Nitriles; Oxidants; Oxidation-Reduction; Peroxides; Rabbits; Vitamin E