What is "d-dopa"

D-DOPA (D-3,4-dihydroxyphenylalanine; dextrodopa) is similar to L-DOPA (levodopa), but with opposite chirality. Levo- and dextro- rotation reference a molecule's ability to rotate planes of polarized light in either direction. Whereas L-DOPA is moderately effective in the treatment of Parkinson's disease (PD) and Dopamine-responsive dystonia (DRD) by stimulating the production of dopamine in the brain, D-DOPA is biologically inactive.