Design, synthesis and biological evaluation of peptide derivatives of l-dopa as anti-parkinsonian agents

A series of dipeptide derivatives of l-dopa were synthesized and investigated for their pharmacological activity using the unilaterally 6-hydroxydopamine (6-OHDA)-lesioned rat as an experimental model of Parkinson's disease. Among them, (S)-isopropyl 2-(2-amino-2-methylpropanamido)-3-(3,4-dihydroxyphenyl)propanoate (4g) was found to be the most active compound, with 106% AUC activity and 149% peak activity of l-dopa after oral administration.