title: Stable isotope studies of phytanic acid alpha-oxidation: in vivo production of formic acid.
abstract: The aim of this study was to test whether formate is formed during alpha-oxidation of phytanic acid in humans. To a healthy volunteer, [1-13C]phytanic acid was given as an oral substrate in a dose of 15 mg/kg body weight, after which plasma, urine and breath air samples were collected during 35 h. The plasma concentrations of [1-13C]-phytanic acid, 2-hydroxy[1-13C]phytanic acid, pristanic acid and [13C]formate were analysed. The [1-13C]phytanic acid concentration increased within 5-7 h to 105 mumol/l, then decreased. Formation of 2-hydroxy[1-13C]phytanic acid increased during the first 11 h after which it decreased during the next 20 h. Pristanic acid increased slightly during the test. In breath air, 13CO2 enrichment was measured, showing a cumulative output of ca. 30% of the ingested dose after 35 h. In both urine and plasma, enrichment of [13C]formate, higher than that of 13CO2 was demonstrated. These findings show that formate is a decarboxylation product in the alpha-oxidation of phytanic acid in vivo.
authors.affiliation: Dept. of Clinical Chemistry, Metabolic Unit, Free University, Hospital, Amsterdam, The Netherlands.
authors.forename: N M
authors.initials: NM
authors.lastname: Verhoeven
authors.forename: D S
authors.initials: DS
authors.lastname: Schor
authors.forename: S F
authors.initials: SF
authors.lastname: Previs
authors.forename: H
authors.initials: H
authors.lastname: Brunengraber
authors.forename: C
authors.initials: C
authors.lastname: Jakobs
mesh_terms: D000328:Adult; D002247:Carbon Isotopes; D005260:Female; D005561:Formates / Q000378:metabolism*; D006801:Humans; D010084:Oxidation-Reduction; D010831:Phytanic Acid / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D005561:Formates; C030544:formic acid; D010831:Phytanic Acid