title: Levodopa-related cysteinyl-glycine and cysteine reduction with and without catechol-O-methyltransferase inhibition in Parkinson's disease patients.
abstract: Oxidative stress is influenced by the thiol homeostasis, which regulates the redox milieu via glutathione. Components of glutathione metabolism are cysteine and cysteinyl-glycine. Both substrates decay following levodopa application or dopamine-related oxidative stress. Objective was to investigate the impact of an acute levodopa application with and without catechol-O-methyltransferase inhibitor on cysteine- and cysteinyl-glycine plasma levels. On two investigation days, 13 patients with Parkinson's disease took one retarded release 200-mg levodopa/50 mg carbidopa-containing tablet or one 150-mg levodopa/50-mg carbidopa/200-mg entacapone formulation under standardized conditions. Levodopa, 3-O-methyldopa, cysteine and cysteinyl-glycine were measured at baseline, 80 and 140 min following levodopa administration. Cysteine and cysteinyl-glycine similarly decreased, levodopa was nearly equal during both conditions. Entacapone lowered 3-O-methyldopa. Cysteine decay may be due to an elevated glutathione generation, which consumes cysteine. Cysteinyl-glycine decrease results from the alternative glutathione transformation to its oxidized form glutathione dissulfide after free radical scavenging.
authors.affiliation: Department of Neurology, St. Joseph Hospital Berlin-Weissensee, Gartenstr. 1, 13088, Berlin, Germany, th.mueller@alexius.de.
authors.forename: Thomas
authors.initials: T
authors.lastname: Müller
authors.forename: Siegfried
authors.initials: S
authors.lastname: Muhlack
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D000978:Antiparkinson Agents / Q000097:blood / Q000627:therapeutic use*; D002230:Carbidopa / Q000097:blood / Q000627:therapeutic use; D002394:Catechol O-Methyltransferase / Q000378:metabolism*; D002396:Catechols / Q000097:blood / Q000627:therapeutic use*; D056148:Chromatography, Reverse-Phase; D003545:Cysteine / Q000097:blood*; D004151:Dipeptides / Q000097:blood*; D016503:Drug Delivery Systems; D005260:Female; D006801:Humans; D007980:Levodopa / Q000097:blood / Q000627:therapeutic use; D008297:Male; D008750:Methyldopa / Q000097:blood; D008875:Middle Aged; D009570:Nitriles / Q000097:blood / Q000627:therapeutic use*; D010300:Parkinson Disease / Q000097:blood / Q000188:drug therapy*; D013997:Time Factors
chemical_list: D000978:Antiparkinson Agents; D002396:Catechols; D004151:Dipeptides; D009570:Nitriles; C028505:cysteinylglycine; D007980:Levodopa; C071192:entacapone; D008750:Methyldopa; D002394:Catechol O-Methyltransferase; D003545:Cysteine; D002230:Carbidopa