title: Structure-based design, synthesis, and biological evaluation of lipophilic-tailed monocationic inhibitors of neuronal nitric oxide synthase.
abstract: Selective inhibitors of neuronal nitric oxide synthase (nNOS) have the potential to develop into new neurodegenerative therapeutics. Recently, we described the discovery of novel nNOS inhibitors (1a and 1b) based on a cis-pyrrolidine pharmacophore. These compounds and related ones were found to have poor blood-brain barrier permeability, presumably because of the basic nitrogens in the molecule. Here, a series of monocationic compounds was designed on the basis of docking experiments using the crystal structures of 1a,b bound to nNOS. These compounds were synthesized and evaluated for their ability to inhibit neuronal nitric oxide synthase. Despite the excellent overlap of these compounds with 1a,b bound to nNOS, they exhibited low potency. This is because they bound in the nNOS active site in the normal orientation rather than the expected flipped orientation used in the computer modeling. The biphenyl or phenoxyphenyl tail is disordered and does not form good protein-ligand interactions. These studies demonstrate the importance of the size and rigidity of the side chain tail and the second basic amino group for nNOS binding efficiency and the importance of the hydrophobic tail for conformational orientation in the active site of nNOS.
authors.affiliation: Department of Chemistry, Center for Molecular Innovation and Drug Discovery, and Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208-3113, USA.
authors.forename: Fengtian
authors.initials: F
authors.lastname: Xue
authors.forename: Jinwen
authors.initials: J
authors.lastname: Huang
authors.forename: Haitao
authors.initials: H
authors.lastname: Ji
authors.forename: Jianguo
authors.initials: J
authors.lastname: Fang
authors.forename: Huiying
authors.initials: H
authors.lastname: Li
authors.forename: Pavel
authors.initials: P
authors.lastname: Martásek
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Roman
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Poulos
authors.forename: Richard B
authors.initials: RB
authors.lastname: Silverman
mesh_terms: D000818:Animals; D002417:Cattle; D015195:Drug Design; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D052248:Nitric Oxide Synthase Type I / Q000037:antagonists & inhibitors* / Q000737:chemistry; D011485:Protein Binding; D011759:Pyrrolidines / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D051381:Rats; D013329:Structure-Activity Relationship
chemical_list: D004791:Enzyme Inhibitors; D011759:Pyrrolidines; D052248:Nitric Oxide Synthase Type I