3-methoxy-L-tyrosine

Methoxytyrosine is one of the main biochemical markers for aromatic L-amino acid decarboxylase deficiency, an inborn error of metabolism that affects serotonin and dopamine biosynthesis. 3-Methoxytyrosine is elevated in CSF, plasma, and urine. Catechol-O-methyl transferase is the enzyme in charge of 3-methoxytyrosine formation, which is produced from L-DOPA in many organs. Nevertheless, its half-life (15 hours approximately) is longer than the L-DOPA 's half-life, which is about one hour. This means that it is accumulated in the plasma and the brain of chronic L-DOPA therapy patients such as people suffering from Parkinson's disease. 3-Methoxytyrosine has some effects on L-DOPA related motor dysfunction, inhibition of striatal uptake of tyrosine, competition with L-DOPA for the blood–brain barrier transporter system and inhibition of dopamine release. 3-Methoxytyrosine increases homocysteine levels, and this amino acid induces cardiovascular disease and neuronal damage. Some other toxic effects could be oxidative DNA damage which can cause cell death, a decrease in locomotor activities and diminishment in mitochondrial membrane potential. (Wikipedia)