p-Nitrostilbene-tert-Butyl-Nitrone: a Novel Fluorescent Spin Trap for the Detection of ROS with Subcellular Resolution

A fluorescent nitrone composed of a nitrostilbene moiety and the tert-butyl-nitrone has been synthesized. Upon addition of short-lived oxygen radicals a relatively stable nitroxide is formed which quenches the fluorescence. Simultaneously, the fluorescence maximum is shifted to shorter wavelength due to the shorter conjugated system. Hence, by means of confocal laser microscopy the formation of reactive oxygen species can be followed with subcellular resolution. The probe co-localizes with mitochondria. Quench was followed in Chinese hamster ovary cells on the second time scale either after generation of hydroxyl radicals by the Fenton reaction or, at almost the same rate, by blocking complexes I and III of the respiratory chain by rotenone and antimycin A. The fluorescence lasted for more than 20 min in controls. The fluorescence decay can be followed in a video presentation on our homepage (http://pcbc00.chemie.uni-kl.de/videostream/stream2java.html). The nature of the initial radical may eventually be determined by electron paramagnetic resonance spectroscopy of the adduct.