Synthesis and enzymatic decarboxylation of 6-bromo-L-dopa, a potential brain tracer for L-dopa

Direct bromination of L-dopa with stoichiometric amounts of molecular bromine was found to yield 6-bromo-L-dopa as the sole product. This determination was made using liquid chromatography with electrochemical detector, mass spectroscopy, and proton NMR. 6-Bromo-L-dopa was found to be a substrate of an isolated decarboxylase enzyme although the rate of decarboxylation was much slower than that for L-dopa. These results suggest that a radiobrominated L-dopa analog may be a suitable PET or SPECT tracer for L-dopa in the brain. (author)