title: Diphenyleneiodonium inhibits the cell redox metabolism and induces oxidative stress.
abstract: Diphenyleneiodonium (DPI) and the structurally related compound diphenyliodonium (DIP) are widely used as inhibitors of flavoenzymes, particularly NADPH oxidase. Here we report further evidence that DPI and DIP are not specific flavin binders. A 3-h incubation of N11 glial cells with DPI significantly inhibited in a dose-dependent way both the pentose phosphate pathway and the tricarboxylic acid cycle. In parallel, we observed a dose-dependent increase of reactive oxygen species generation and lipoperoxidation and increased leakage of lactate dehydrogenase activity in the extracellular medium. The glutathione/glutathione disulfide ratio decreased, whereas the efflux of glutathione out of the cells increased. This suggests that DPI causes an augmented oxidative stress and exerts a cytotoxic effect in N11 cells. Indeed, the cells were protected from these events when loaded with glutathione. Similar results were observed using DIP instead of DPI and also in other cell types. We suggest that the DPI-elicited inhibition of the pentose phosphate pathway and tricarboxylic acid cycle may be mediated by the blockade of several NAD(P)-dependent enzymes, such as glucose 6-phosphate dehydrogenase, glyceraldehyde 3-phosphate dehydrogenase, and lactate dehydrogenase. In light of these results, we think that some effects of DPI or DIP in in vitro and in vivo experimental models should be interpreted with caution.
authors.affiliation: Department of Genetics, Biology, and Biochemistry, University of Torino, Via Santena 5/bis, 10126 Torino, Italy.
authors.forename: Chiara
authors.initials: C
authors.lastname: Riganti
authors.forename: Elena
authors.initials: E
authors.lastname: Gazzano
authors.forename: Manuela
authors.initials: M
authors.lastname: Polimeni
authors.forename: Costanzo
authors.initials: C
authors.lastname: Costamagna
authors.forename: Amalia
authors.initials: A
authors.lastname: Bosia
authors.forename: Dario
authors.initials: D
authors.lastname: Ghigo
mesh_terms: D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology; D002460:Cell Line; D002952:Citric Acid Cycle / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005947:Glucose; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D051379:Mice; D009457:Neuroglia / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009861:Onium Compounds / Q000494:pharmacology*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D010734:Phosphogluconate Dehydrogenase / Q000378:metabolism
chemical_list: D001713:Biphenyl Compounds; D004791:Enzyme Inhibitors; D009861:Onium Compounds; C031291:diphenyliodonium; C007517:diphenyleneiodonium; D007770:L-Lactate Dehydrogenase; D010734:Phosphogluconate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D005978:Glutathione; D005947:Glucose