Tohru Sawai (1), Makoto Asada (1), Yukio Nishizawa (1), Hiroyuki Nunoi
(2) and Kouichi Katayama (1)
(1) Department of Drug Discovery, Eisai Tsukuba Research Laboratories, 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan
(2) Department of Pediatrics, Kumamoto University School of Medicine, 1-1-1 Honjo, Kumamoto 860-8556, Japan
Abstract: Alkylamines inhibit NADPH oxidase both in intact neutrophils and in a cell-free system. The aim of this study was to examine the mechanism underlying this inhibitory effect. Among alkylamines with different chain lengths, the C12 compound (laurylamine) showed the greatest inhibitory effect on the cell-free NADPH oxidase activity induced by arachidonic acid (AA) in the presence of GTPgammaS. The inhibition was overcome by further addition of AA, and it was observed irrespective of whether laurylamine was added before or after the enzyme activation by AA. When added prior to the enzyme activation, laurylamine blocked translocation to the membrane of all three cytosolic components (p47-phox, p67-phox and rac) in a cell-free translocation assay. When added after the activation, laurylamine released only rac from the membrane. Laurylamine did not inhibit the reduction of cytochrome c by xanthine oxidase, suggesting that it does not have superoxide-scavenging activity. These results indicate that laurylamine inhibits both the activation process of NADPH oxidase and the activated enzyme itself by blocking the assembly of the oxidase components.
Keywords: NADPH oxidase, Alkylamine, Arachidonic acid, Translocation, Neutrophil