Modification by ferrocene: An approach to enhance antioxidant ability of ailanthoidol to protect DNA.

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.