Synthesis, structural investigations and biological evaluation of novel hexahydropyridazine-1-carboximidamides, -carbothioamides and -carbothioimidic acid esters as inducible nitric oxide synthase inhibitors.
Local excess of nitric oxide (NO) has been implicated in beta-cell damage, thus, a possible approach to the treatment of autoimmune IDDM is the selective inhibition of inducible nitric oxide synthase (iNOS). A series of variously substituted hexahydropyridazine-1-carbothioamides, -carbothioimidic acid esters and -carboximidamides was synthesized and dose-dependently evaluated as potential inhibitors of iNOS. The screening of the title compounds was performed with insulin-producing RIN-5AH cells and a combination of IL1-1 beta and IFN-gamma as inducers of cellular NO production. The structure-activity analysis revealed that the variation of substituents in the position 1 of the hexahydropyridazine strongly influences the inhibitory activity to iNOS as well as being critical for RIN cell survival. Among the compounds tested, the hexahydropyridazine-1-carbothioamides showed particularly significant inhibitory effects. However, for an efficient iNOS inhibition substitution at the nitrogen of the 1-carbothioamide group is important. Thus, the introduction of aliphatic chains such as propyl or butyl and of cyclic moieties such as cyclohexyl, 3-methoxyphenyl, and 4-methoxyphenyl (IC(50): 0.5-2.1 mM), respectively, provided compounds with similar inhibitory activity to aminoguanidine (IC(50): 0.3 mM), a common standard substance used for the selective inhibition of iNOS. However, the 1-carboximidamides, which represent more structurally related semicyclic derivatives of aminoguanidine, caused only incomplete iNOS inhibition. The hexahydropyridazine-1-carbothioimidic acid esters caused dose- and substituent-dependent damage of RIN-5AH cells. The toxicity of the synthesized compounds increased markedly if aliphatic substituents at the exocyclic N atom(s) were replaced by variously substituted aromatic rings.
Ernst-Moritz-Arndt-Universität Greifswald, Institut für Pharmazie, Friedrich-Ludwig-Jahn- Strasse 17, D-17487 Greifswald, Germany. omorgens@uni-greifswald.de
Olaf
O
Morgenstern
Heike
H
Wanka
Ilka
I
Röser
Antje
A
Steveling
Beate
B
Kuttler
D000577:Amides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D002460:Cell Line; D003922:Diabetes Mellitus, Type 1 / Q000188:drug therapy / Q000473:pathology; D006801:Humans; D007096:Imidoesters / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D020128:Inhibitory Concentration 50; D009569:Nitric Oxide / Q000032:analysis / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D052247:Nitric Oxide Synthase Type II; D013329:Structure-Activity Relationship
D000577:Amides; D007096:Imidoesters; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II