title: Thiol-induced nitric oxide release from 3-halogeno-3,4-dihydrodiazete 1,2-dioxides.
abstract: In this work we studied the mechanism of nitric oxide (NO) release underlying the vasorelaxant and antiaggregant effect of 3,4-dihydrodiazete 1,2-dioxides (DD). Six derivatives were included in the investigations, namely, 3-bromo- and 3-chloro-3,4,4-trimethyl-DD (1a,b), 3-bromo- and 3-chloro-4-methyl-3,4-hexamethylene-DD (2a,b), 3,3,4,4-tetramethyl-DD (3), and 3-methyl-3,4-hexamethylene-DD (4), and their reactivity toward thiols was analyzed. The 3-bromo- and 3-chloro-DD derivatives were found to react with thiols; this reaction can lead to NO formation, DD 2a being the most reactive compound. 2-(Hydroxyamino)-2-methylbutan-3-one oxime (5a) and 2-hydroxy-2-methylbutan-3-one oxime (6) were the main products isolated from the reaction of 1a with cysteine. Reaction rates of DD with thiols were dependent upon pH and concentration of the reagents. Maximum rates of NO release corresponded to thiol concentrations in the range of 1 mM. Consistent with reaction kinetics data and products isolated, a reaction mechanism was proposed. Addition of 2a to bovine aortic endothelial cells led to strong NO release indicating a reaction with endogenous thiols. In rat mesenterial arteries, the vasorelaxant action of 2a was only slightly influenced by addition of thiol to the incubation medium. For the most reactive DD derivatives, cytotoxic effects were observed at concentrations roughly 2 orders of magnitude higher than those inducing vasorelaxation.
authors.affiliation: Novosibirsk Institute of Organic Chemistry, Russia.
authors.forename: I A
authors.initials: IA
authors.lastname: Kirilyuk
authors.forename: D I
authors.initials: DI
authors.lastname: Utepbergenov
authors.forename: D G
authors.initials: DG
authors.lastname: Mazhukin
authors.forename: K
authors.initials: K
authors.lastname: Fechner
authors.forename: K
authors.initials: K
authors.lastname: Mertsch
authors.forename: V V
authors.initials: VV
authors.lastname: Khramtsov
authors.forename: I E
authors.initials: IE
authors.lastname: Blasig
authors.forename: R F
authors.initials: RF
authors.lastname: Haseloff
mesh_terms: D000818:Animals; D003497:Cyclic N-Oxides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D008638:Mesenteric Arteries; D009569:Nitric Oxide / Q000737:chemistry*; D051381:Rats; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014664:Vasodilation; D014665:Vasodilator Agents / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology
chemical_list: D003497:Cyclic N-Oxides; D013438:Sulfhydryl Compounds; D014665:Vasodilator Agents; D009569:Nitric Oxide