Novel bisbenzimide-nitroxides for nuclear redox imaging in living cells

Nuclear oxidative stress damages genomic DNA and may lead to cell death, leading to aging and aging-related disorders. Though it is important to measure the nuclear oxidative stress separately, there are still little examples that applicable to living cells. We have designed and synthesized three bisbenzimide-nitroxides as probes to selectively visualize nuclear redox changes in terms of fluorescence. Compound 3, containing two radical moieties, showed the largest reduction-induced fluorescence change, with good localization in nuclei. RAW264.7 murine macrophage cells were loaded with compound 3 and then treated with 100μM hydrogen peroxide for 5min to show the fluorescence increase. This fluorescence increase was inhibited by pretreatment of 1mM ascorbic acid. These results show that compound 3 was suitable for nuclear-specific redox imaging in murine macrophages.