title: The identification and kinetics of 7 alpha-hydroxyriboflavin (7-hydroxymethylriboflavin) in blood plasma from humans following oral administration of riboflavin supplements.
abstract: Following the administration of different oral (20, 40, 60 mg) and intravenous (11.6 mg) doses of riboflavin to healthy humans and female patients with liver cirrhosis (oral 40-mg dose), 7 alpha-hydroxyriboflavin (7-hydroxymethylriboflavin) was identified in blood plasma by fluorescence after high-performance liquid and thin-layer chromatographies, and by its absorbance spectrum. The apparent first-order absorption rate constant of 7 alpha-hydroxyriboflavin was 1.2 per hour in healthy subjects. Plasma peak concentrations of 40 nmol/l in males and 20 nmol/l in females (p < 0.01) were achieved within two hours. Peak concentrations and areas under the plasma curves (smaller in females, p < 0.01) of 7 alpha-hydroxyriboflavin were 5 to 16% of those observed for riboflavin. Healthy females showed an approximately 2.5-fold faster disposition of 7 alpha-hydroxyriboflavin from plasma than males (p < 0.01). Correction of peak concentrations and areas under the plasma curves by the rate constants of disposition led to the finding of approximately equal amounts of 7 alpha-hydroxyriboflavin released into plasma by both sexes (p > 0.05). No significant influence of different oral riboflavin doses on 7 alpha-hydroxyriboflavin kinetics was found (p > 0.05). Liver cirrhosis had no significant effect on the amount of 7 alpha-hydroxyriboflavin released into blood plasma (p > 0.05). However, the failure to detect this metabolite following intravenous riboflavin administration indicates a substantial influence of gastrointestinal- or liver-passage.
authors.affiliation: Dept. of Biochemistry, Rollins Research Center, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: J
authors.initials: J
authors.lastname: Zempleni
authors.forename: J R
authors.initials: JR
authors.lastname: Galloway
authors.forename: D B
authors.initials: DB
authors.lastname: McCormick
mesh_terms: D000042:Absorption; D000284:Administration, Oral; D000328:Adult; D002851:Chromatography, High Pressure Liquid; D002855:Chromatography, Thin Layer; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008103:Liver Cirrhosis / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D012256:Riboflavin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics*; D013056:Spectrophotometry, Ultraviolet
chemical_list: C038138:7-hydroxymethylriboflavin; D012256:Riboflavin