dopa (dihydroxyphenylalanine) A derivative of the amino acid tyrosine. It is found in particularly high levels in the adrenal glands and is a precursor in the synthesis of dopamine, noradrenaline, and adrenaline. The laevorotatory form, L-dopa (levodopa), is administered in the treatment of Parkinson's disease, in which brain levels of dopamine are reduced.

dopa (doh-pă) n. dihydroxyphenylalanine: a physiologically important compound that forms an intermediate stage in the synthesis of catecholamines from the essential amino acid tyrosine. The laevorotatory form, levodopa, is administered for the treatment of parkinsonism.