title: Methyl group-donating vitamins elevate 3-O-methyldopa in patients with Parkinson disease.
abstract: BACKGROUND
  Levodopa (LD)/dopa decarboxylase inhibitor application increases 3-O-methyldopa (3-OMD) concentrations in association with methyl group transfers, which demand for the conversion of methionine to homocysteine. This accompanying reaction is partially reversible by methyl group-donating vitamins.
  
  
  OBJECTIVE
  The objective of this study was to investigate of the effect of methyl group-donating vitamins on 3-OMD synthesis in LD-treated patients with Parkinson disease.
  
  
  METHODS
  We determined LD, 3-OMD, and homocysteine plasma concentrations in relation to daily LD dosage administered orally or as duodenal infusion with and without vitamins.
  
  
  RESULTS
  Orally LD-treated patients with Parkinson disease had a lower LD dose compared with the ones on an LD infusion, but LD, 3-OMD, and homocysteine bioavailability was not different. The same 3-OMD and homocysteine accumulation despite the applied higher LD dosage during the infusion indicates a limited methylation capacity. Higher 3-OMD concentrations occurred during chronic vitamin supplementation, whereas the other parameters did not vary from the ones before vitamin intake.
  
  
  CONCLUSIONS
  Vitamin supplementation elevated methylation of LD to 3-OMD. We suggest that, to a certain extent, plasma levels of homocysteine may reflect methyl group donation resources, whereas 3-OMD concentrations may mirror methylation capacity.
authors.affiliation: Department of Neurology, St Joseph Hospital Berlin-Weissensee, Berlin, Germany. th.mueller@alexius.de
authors.forename: Thomas
authors.initials: T
authors.lastname: Müller
authors.forename: Constanze
authors.initials: C
authors.lastname: Jugel
authors.forename: Siegfried
authors.initials: S
authors.lastname: Muhlack
authors.forename: Fabian
authors.initials: F
authors.lastname: Klostermann
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000978:Antiparkinson Agents / Q000378:metabolism / Q000627:therapeutic use*; D015415:Biomarkers / Q000378:metabolism; D015331:Cohort Studies; D005260:Female; D006710:Homocysteine / Q000097:blood / Q000378:metabolism; D006801:Humans; D007980:Levodopa / Q000378:metabolism* / Q000627:therapeutic use; D008297:Male; D008745:Methylation / Q000187:drug effects; D008875:Middle Aged; D010300:Parkinson Disease / Q000188:drug therapy* / Q000378:metabolism; D010865:Pilot Projects; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000096:biosynthesis; D014815:Vitamins / Q000378:metabolism / Q000493:pharmacokinetics*
chemical_list: D000978:Antiparkinson Agents; D015415:Biomarkers; D014815:Vitamins; D006710:Homocysteine; D014443:Tyrosine; D007980:Levodopa; C008404:3-methoxytyrosine