Characterization and Discovery of a Selective Small-Molecule Modulator of Mitochondrial Complex I Targeting a Unique Binding Site.

Mitochondrial dysfunction has been recognized as an essential contributor to many human diseases including neurodegenerative disorders. However, the exact pathological role of mitochondrial dysfunction, especially in mitochondrial reactive oxygen species-associated oxidative stress, remains elusive, partially due to the lack of chemical probes with well-defined mechanisms of action. Herein, we describe the characterization and discovery of a rationally designed small molecule as a selective modulator of the production of reactive oxygen species from mitochondrial complex I that does not alter mitochondrial membrane potential and bioenergetics. Chemical biology studies employing photoaffinity probes derived from demonstrated its novel mechanism of action of modulating complex I via interactions with the flavin mononucleotide site, proximal in the reaction pathway within complex I.