2-Methylcitric acid impairs glutamate metabolism and induces permeability transition in brain mitochondria. It inhibits glutamate dehydrogenase (GDH) activity at concentrations as low as 0.5 mM. 2-Methylcitric acid (1-3 mM; 150 seconds) provokes a significant decrease in mitochondrial membrane potential and induced swelling in Ca2+-loaded mitochondria supported by different substrates. 2-Methylcitric acid behaves as a potent inhibitor of glutamate oxidation by inhibiting glutamate dehydrogenase activity and as a permeability transition inducer, disturbing mitochondrial energy homeostasis. 2-Methylcitric acid does not significantly impair mitochondrial glutamate transport. 2-Methylcitric acid does not significantly impair glutamate mitochondrial transport in liver mitochondria.