title: Structure-based design, synthesis, and structure-activity relationship studies of novel non-nucleoside adenosine deaminase inhibitors.
abstract: We disclose herein optimization efforts around the novel, highly potent non-nucleoside adenosine deaminase (ADA) inhibitor, 1-[(R)-1-hydroxy-4-(6-(3-(1-methylbenzimidazol-2-yl)propionylamino)indol-1-yl)-2-butyl]imidazole-4-carboxamide 1 (K(i)= 7.7 nM), which we recently reported. Structure-based drug design (SBDD) utilizing the crystal structure of the 1/ADA complex was performed in order to obtain structure-activity relationships (SAR) for this type of compound rationally and effectively. To utilize the newly formed hydrophobic space (F2), replacement of the benzimidazole ring of 1 with a n-propyl chain (4b) or a simple phenyl ring (4c) was tolerated in terms of binding activity, and the length of the methylene-spacer was shown to be optimal at two or three. Replacement of an amide with an ether as a linker was also well tolerated in terms of binding activity and moreover improved the oral absorption (6a and 6b). Finally, transformation of indol-1-yl to indol-3-yl resulted in discovery of a novel highly potent and orally bioavailable ADA inhibitor, 1-[(R)-4-(5-(3-(4-chlorophenyl)propoxy)-1-methylindol-3-yl)-1-hydroxy-2-butyl]imidazole-4-carboxamide 8c.
authors.affiliation: Medicinal Chemistry Research Laboratories, Fujisawa Pharmaceutical Co., Ltd., 2-1-6, Kashima, Yodogawa-ku, Osaka 532-8514, Japan. tadashi_terasaka@po.fujisawa.co.jp
authors.forename: Tadashi
authors.initials: T
authors.lastname: Terasaka
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Kinoshita
authors.forename: Masako
authors.initials: M
authors.lastname: Kuno
authors.forename: Nobuo
authors.initials: N
authors.lastname: Seki
authors.forename: Kohichiro
authors.initials: K
authors.lastname: Tanaka
authors.forename: Isao
authors.initials: I
authors.lastname: Nakanishi
mesh_terms: D000243:Adenosine Deaminase / Q000737:chemistry; D058892:Adenosine Deaminase Inhibitors; D000577:Amides / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D000818:Animals; D018360:Crystallography, X-Ray; D015195:Drug Design; D007093:Imidazoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D008297:Male; D008958:Models, Molecular; D051381:Rats; D017207:Rats, Sprague-Dawley; D013329:Structure-Activity Relationship; D014508:Urea / Q000737:chemistry
chemical_list: C488439:1-(4-(5-(3-(4-chlorophenyl)propoxy)-1-methylindol-3-yl)-1-hydroxy-2-butyl)imidazole-4-carboxamide; D058892:Adenosine Deaminase Inhibitors; D000577:Amides; D007093:Imidazoles; D007211:Indoles; D014508:Urea; D000243:Adenosine Deaminase