title: Nitric oxide-donating properties of mesoionic 3-aryl substituted oxatriazole-5-imine derivatives.
abstract: 1. The nitric oxide (NO)-releasing properties of two new mesoionic 3-aryl substituted oxatriazole-5-imine derivatives (GEA 3162 and GEA 3175) were characterized and compared with the known NO-donors 3-morpholino-sydnonimine (SIN-1) and S-nitroso-N-acetylpenicillamine (SNAP). 2. GEA 3162, GEA 3175, SIN-1 and SNAP inhibited adenosine 5'-diphosphate-induced platelet aggregation (IC50 values 0.18, 0.39, 3.73 and 2.12 microM, respectively). All four compounds induced a dose-dependent and more than 4 fold increase in cyclic GMP in platelets. The increase in cyclic GMP concentration was potentiated more than 1.5 fold by a phosphodiesterase inhibitor, zaprinast (10 microM) and inhibited 38-97% by oxyhaemoglobin (10-45 microM). 3. All of the four compounds studied converted oxyhaemoglobin to methaemoglobin and formed a paramagnetic NO-haemoglobin complex. All but GEA 3175 formed nitrite and nitrate in phosphate buffer. During a 40 min incubation, GEA 3162, SIN-1 and SNAP (100 microM) produced 50-70 microM NO2- + NO3- as determined by high performance liquid chromatography. The release of NO and NO2 by GEA 3175 was increased 140 fold in the presence of human plasma (0.14 and 19.7 ppb in the absence and presence of 1% human plasma, respectively) as analyzed by ozone chemiluminescence. 4. The results suggest that the mesoionic 3-aryl substituted oxatriazole-5-imine derivatives GEA 3162 and GEA 3175 as well as SIN-1 and SNAP release nitric oxide.
authors.affiliation: Medical School, University of Tampere, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Kankaanranta
authors.forename: E
authors.initials: E
authors.lastname: Rydell
authors.forename: A S
authors.initials: AS
authors.lastname: Petersson
authors.forename: P
authors.initials: P
authors.lastname: Holm
authors.forename: E
authors.initials: E
authors.lastname: Moilanen
authors.forename: T
authors.initials: T
authors.lastname: Corell
authors.forename: G
authors.initials: G
authors.lastname: Karup
authors.forename: P
authors.initials: P
authors.lastname: Vuorinen
authors.forename: S B
authors.initials: SB
authors.lastname: Pedersen
authors.forename: A
authors.initials: A
authors.lastname: Wennmalm
authors.forename: T
authors.initials: T
authors.lastname: Metsä-Ketelä
mesh_terms: D001792:Blood Platelets / Q000187:drug effects / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D006152:Cyclic GMP / Q000097:blood; D004578:Electron Spin Resonance Spectroscopy; D006801:Humans; D066298:In Vitro Techniques; D008163:Luminescent Measurements; D008706:Methemoglobin / Q000737:chemistry / Q000378:metabolism; D009566:Nitrates / Q000032:analysis; D009569:Nitric Oxide / Q000378:metabolism*; D009573:Nitrites / Q000032:analysis; D010108:Oxyhemoglobins / Q000737:chemistry / Q000378:metabolism; D010974:Platelet Aggregation / Q000187:drug effects; D014230:Triazoles / Q000737:chemistry / Q000494:pharmacology*
chemical_list: C093084:GEA 3175; D009566:Nitrates; D009573:Nitrites; D010108:Oxyhemoglobins; D014230:Triazoles; D009569:Nitric Oxide; C082874:GEA 3162; D008706:Methemoglobin; D006152:Cyclic GMP