title: Benfotiamine exhibits direct antioxidative capacity and prevents induction of DNA damage in vitro.
abstract: BACKGROUND
  Complications in diabetes mellitus are partially mediated by enhanced formation of reactive oxygen species. Among the factors involved in reactive oxygen species formation, advanced glycation end products play a key role. Owing to a reduced activity of the enzyme transketolase, which requires diphosphorylated thiamine (vitamin B(1)) as cofactor, an accumulation of those deleterious glucose metabolites especially in diabetic patients can be observed. Benfotiamine, a lipophilic thiamine diphosphate prodrug, prevented early renal and retinal changes in animal studies, and reduced neuropathic pain in clinical studies. Several mechanisms for these activities have been described. We investigated for the first time direct antioxidant abilities of benfotiamine. Additionally, a potential DNA protective effect of benfotiamine was analysed.
  
  
  METHODS
  Oxidative stress was detected by flow cytometry, antioxidative capacity was measured with the ferric reducing ability of plasma (FRAP) assay, two endpoints for genomic damage were assessed: the comet assay and the micronucleus test, and the expression and activity of transketolase was quantified.
  
  
  RESULTS
  Benfotiamine prevented oxidative stress induced by the mutagen 4-nitroquinoline-1-oxide (NQO), the uremic toxin indoxyl sulfate, and the peptide hormone angiotensin II in three different kidney cell lines. Cell-free experiments showed a direct antioxidant effect of benfotiamine, which might account for the protective effect. Oxidative DNA damage, induced by angiotensin II, was completely prevented by benfotiamine. Incubation with benfotiamine increased transketolase expression and activity in the cells.
  
  
  CONCLUSIONS
  Benfotiamine shows a direct antioxidant action. This effect of benfotiamine may be involved in the improvement of diabetic late complications, including peripheral neuropathy.
authors.affiliation: Institute of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany.
authors.forename: Ursula
authors.initials: U
authors.lastname: Schmid
authors.forename: Helga
authors.initials: H
authors.lastname: Stopper
authors.forename: August
authors.initials: A
authors.lastname: Heidland
authors.forename: Nicole
authors.initials: N
authors.lastname: Schupp
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004249:DNA Damage / Q000187:drug effects*; D006801:Humans; D018374:LLC-PK1 Cells; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D013831:Thiamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D014174:Transketolase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D014174:Transketolase; D013831:Thiamine; C013835:benphothiamine