title: Neuroprotection by minocycline caused by direct and specific scavenging of peroxynitrite.
abstract: Minocycline prevents oxidative protein modifications and damage in disease models associated with inflammatory glial activation and oxidative stress. Although the drug has been assumed to act by preventing the up-regulation of proinflammatory enzymes, we probed here its direct chemical interaction with reactive oxygen species. The antibiotic did not react with superoxide or (•)NO radicals, but peroxynitrite (PON) was scavenged in the range of ∼1 μm minocycline and below. The interaction of pharmacologically relevant minocycline concentrations with PON was corroborated in several assay systems and significantly exceeded the efficacy of other antibiotics. Minocycline was degraded during the reaction with PON, and the resultant products lacked antioxidant properties. The antioxidant activity of minocycline extended to cellular systems, because it prevented neuronal mitochondrial DNA damage and glutathione depletion. Maintenance of neuronal viability under PON stress was shown to be solely dependent on direct chemical scavenging by minocycline. We chose α-synuclein (ASYN), known from Parkinsonian pathology as a biologically relevant target in chemical and cellular nitration reactions. Submicromolar concentrations of minocycline prevented tyrosine nitration of ASYN by PON. Mass spectrometric analysis revealed that minocycline impeded nitrations more effectively than methionine oxidations and dimerizations of ASYN, which are secondary reactions under PON stress. Thus, PON scavenging at low concentrations is a novel feature of minocycline and may help to explain its pharmacological activity.
authors.affiliation: Department of In Vitro Toxicology and Biomedicine, Faculty of Biology, University of Konstanz, 78457 Konstanz, Germany. Stefan.Schildknecht@uni-konstanz.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Schildknecht
authors.forename: Regina
authors.initials: R
authors.lastname: Pape
authors.forename: Nathalie
authors.initials: N
authors.lastname: Müller
authors.forename: Marta
authors.initials: M
authors.lastname: Robotta
authors.forename: Andreas
authors.initials: A
authors.lastname: Marquardt
authors.forename: Alexander
authors.initials: A
authors.lastname: Bürkle
authors.forename: Malte
authors.initials: M
authors.lastname: Drescher
authors.forename: Marcel
authors.initials: M
authors.lastname: Leist
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D002461:Cell Line, Transformed; D004249:DNA Damage / Q000187:drug effects; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008911:Minocycline / Q000737:chemistry* / Q000494:pharmacology; D009474:Neurons / Q000737:chemistry / Q000378:metabolism; D018696:Neuroprotective Agents / Q000737:chemistry* / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D030421:Peroxynitrous Acid / Q000737:chemistry* / Q000378:metabolism; D055503:Protein Multimerization / Q000187:drug effects; D051844:alpha-Synuclein / Q000737:chemistry / Q000378:metabolism
chemical_list: D000900:Anti-Bacterial Agents; D004272:DNA, Mitochondrial; D018696:Neuroprotective Agents; D051844:alpha-Synuclein; D030421:Peroxynitrous Acid; D008911:Minocycline