m-Hydroxyphenylacetic acid formation from L-dopa in man: suppression by neomycin

Science. 1969 Dec 12;166(3911):1417-8. doi: 10.1126/science.166.3911.1417.


The increased excretion of m-hydroxyphenylacetic acid in the urine of patients with parkinsonism being treated with L-dopa was reduced by gut sterilization with neomycin. The p-de-hydroxylation step is thus brought about solely by the action of gut flora; the pathway is unlikely to be involved in the events within the brain leading to the therapeutic benefit effected by L-dopa.

MeSH terms

  • Dihydroxyphenylalanine / metabolism*
  • Humans
  • Intestines / microbiology
  • Neomycin / administration & dosage*
  • Parkinson Disease / drug therapy
  • Parkinson Disease / metabolism*
  • Parkinson Disease / urine
  • Phenylacetates / urine*


  • Phenylacetates
  • Dihydroxyphenylalanine
  • Neomycin