MitoNeoD: A Mitochondria-Targeted Superoxide Probe

Mitochondrial superoxide (O2⋅-) underlies much oxidative damage and redox signaling. Fluorescent probes can detect O2⋅-, but are of limited applicability in vivo, while in cells their usefulness is constrained by side reactions and DNA intercalation. To overcome these limitations, we developed a dual-purpose mitochondrial O2⋅- probe, MitoNeoD, which can assess O2⋅- changes in vivo by mass spectrometry and in vitro by fluorescence. MitoNeoD comprises a O2⋅--sensitive reduced phenanthridinium moiety modified to prevent DNA intercalation, as well as a carbon-deuterium bond to enhance its selectivity for O2⋅- over non-specific oxidation, and a triphenylphosphonium lipophilic cation moiety leading to the rapid accumulation within mitochondria. We demonstrated that MitoNeoD was a versatile and robust probe to assess changes in mitochondrial O2⋅- from isolated mitochondria to animal models, thus offering a way to examine the many roles of mitochondrial O2⋅- production in health and disease.