title: Ability of dorzolamide hydrochloride and timolol maleate to target mitochondria in glaucoma therapy.
abstract: OBJECTIVE
  To test the ability of dorzolamide hydrochloride and timolol maleate to display antioxidant effects.
  
  
  METHODS
  Antioxidant activity was tested in whole trabecular meshwork (TM) tissue as collected from corneal donors' biopsy specimens, young (third passage) and old (10th passage) human TM cells, and acellular systems composed of pure DNA and subcellular fractions containing or devoid of mitochondria. Oxidative stress was induced by hydrogen peroxide. Monitored end points included DNA fragmentation as evaluated by the halo test, oxidative DNA damage in terms of 8-hydroxy-2'-deoxyguanosine, and mitochondrial function as evaluated by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide test.
  
  
  RESULTS
  The antioxidant effect of dorzolamide and timolol were observed on TM biopsy specimens and human TM cells exposed to hydrogen peroxide. As evaluated in cell subfractions, timolol displays antioxidant activity regardless of mitochondria presence. Conversely, the antioxidant activity of dorzolamide was maximized in the presence of mitochondria-containing subcellular fractions and in young human TM cells with functional mitochondria.
  
  
  CONCLUSIONS
  The antioxidant effect of timolol was direct. The antioxidant effect of dorzolamide involves mitochondria and is likely to be exerted mainly during the early glaucoma phases when the mitochondrial damage in the TM tissue still occurs at low levels. Clinical Relevance  Timolol has an antioxidant effect on the entire cell, whereas dorzolamide exerts protective activity toward oxidative stress only in the presence of intact mitochondria (ie, in endothelial cells that are younger when the cellular damage is still limited). The important role of mitochondrial damage in primary open- angle glaucoma is supported by the finding that mutant myocilin impairs mitochondrial functions in human TM meshwork cells.
authors.affiliation: Ophthalmology Unit, Department of Head/Neck Pathologies, San Martino Hospital, Viale Benedetto XV, 16132 Genoa, Italy. sergio.sacca@hsanmartino.it
authors.forename: Sergio Claudio
authors.initials: SC
authors.lastname: Saccà
authors.forename: Sebastiano
authors.initials: S
authors.lastname: La Maestra
authors.forename: Rosanna T
authors.initials: RT
authors.lastname: Micale
authors.forename: Patrizia
authors.initials: P
authors.lastname: Larghero
authors.forename: Giorgia
authors.initials: G
authors.lastname: Travaini
authors.forename: Barbara
authors.initials: B
authors.lastname: Baluce
authors.forename: Alberto
authors.initials: A
authors.lastname: Izzotti
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000975:Antioxidants / Q000494:pharmacology*; D001345:Autoradiography; D002460:Cell Line; D002855:Chromatography, Thin Layer; D053938:DNA Fragmentation; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D005902:Glaucoma, Open-Angle / Q000188:drug therapy*; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity; D008928:Mitochondria / Q000187:drug effects*; D018384:Oxidative Stress / Q000187:drug effects; D013449:Sulfonamides / Q000494:pharmacology*; D013876:Thiophenes / Q000494:pharmacology*; D013999:Timolol / Q000494:pharmacology*; D014019:Tissue Donors; D014129:Trabecular Meshwork / Q000187:drug effects*
chemical_list: D000975:Antioxidants; D013449:Sulfonamides; D013876:Thiophenes; D013999:Timolol; D000080242:8-Hydroxy-2'-Deoxyguanosine; C062765:dorzolamide; D006861:Hydrogen Peroxide; D003849:Deoxyguanosine