Physiological levels of formate activate mitochondrial superoxide/hydrogen peroxide release from mouse liver mitochondria

Here, we found that formate, an essential one‐carbon metabolite, activates superoxide ( )/hydrogen peroxide (H 2 O 2 ) release from mitochondria. Sodium formate (30 μ m ) induces a significant increase in /H 2 O 2 production in liver mitochondria metabolizing pyruvate (50 μ m ). At concentrations deemed to be toxic, formate does not increase /H 2 O 2 production further. It was observed that the formate‐mediated increase in /H 2 O 2 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.