3-Methoxytyrosine is an active metabolite of L-DOPA .1 It is formed from L-DOPA via O-methylation by catechol-O-methyltransferase (COMT). 3-Methoxytyrosine (10 and 100 µM) inhibits L-DOPA-induced neuroprotection in primary rat mesencephalic dopaminergic neurons.2
1.Miller, J.W., Shukitt-Hale, B., Villalobos-Molina, R., et al.Effect of ?-Dopa and the catechol-O-methyltransferase inhibitor Ro 41-0960 on sulfur amino acid metabolites in ratsClin. Neuropharmacol.20(1)55-66(1997) 2.Asanuma, M., and Miyazaki, I.3-O-Methyldopa inhibits astrocyte-mediated dopaminergic neuroprotective effects of ?-DOPABMC Neurosci.17(1)52(2016)