LAUSR

Here, we found that formate, an essential one‐carbon metabolite, activates superoxide ( O2·− )/hydrogen peroxide (H2O2) release from mitochondria. Sodium formate (30 μm) induces a significant increase in O2·− /H2O2 production in liver mitochondria metabolizing pyruvate (50 μm). At concentrations deemed to be toxic, formate does not increase O2·− /H2O2 production further. It was observed that the formate‐mediated increase in O2·− /H2O2 production is not associated with cytochrome c oxidase (COX) inhibition or changes in membrane potential and NAD(P)H levels. Sodium formate supplementation increases phosphorylating respiration without altering proton leaks. Finally, it was observed that the 2‐oxoglutarate dehydrogenase (OGDH) inhibitors 3‐methyl‐2‐oxovaleric acid (KMV) and CPI‐613 inhibit the formate‐induced increase in pyruvate‐driven ROS production. The importance of these findings in one‐carbon metabolism and physiology are discussed herein.