L-dopa
![L-dopa structural formula](../../images2/L-dopa.gif)
L-dopa, also called levodopa, is a naturally-occurring isomer of an amino acid used to relieve some symptoms of Parkinson's disease. It sometimes suppresses the trembling, unsteadiness, and slowness of movement that characterizes the condition. Side-effects include involuntary facial movements, mood swings, loss of appetite, nausea, vomiting, and dizziness.