Ferrocenyl-substituted curcumin: can it influence antioxidant ability to protect DNA?

The antioxidant capacities of ferrocenyl-substituted curcumin derivatives including 1,7-bis(p-hydroxy-m-methoxyphenyl)-4-ferrocenylidene-hepta-1,6-diene-3,5-dione (FCU), 1-(p-hydroxy-m-methoxyphenyl)-3-hydroxy-7-ferrocenyl-hepta-1,4,6-trien-5-one (FFT), and 1-(p-hydroxy-m-methoxyphenyl)-5-ferrocenyl-penta-1,4-dien-3-one (FDZ) were evaluated in 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH), Cu2+/glutathione (GSH), and hydroxyl radical (.OH)-induced oxidation of DNA, and in trapping 2,2'-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS+), and galvinoxyl radicals. FCU, FFT, and FDZ protected DNA against Cu2+/GSH-induced oxidation, but promoted .OH-induced oxidation of DNA. FCU, FFT, and FDZ scavenged 9.5, 5.7, and 4.7 radicals in protecting DNA against AAPH-induced oxidation. FCU can trap more DPPH and ABTS+ than FDZ and FFT, whereas FCU, FFT, and FDZ cannot react with galvinoxyl radical. Both phenolic hydroxyl groups and iron atom in ferrocenylidene curcumin derivatives play antioxidant role in this case.