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Featured researches published by Takayuki Namiki.
Bioorganic & Medicinal Chemistry | 2003
Makoto Kimura; Tomoko Masuda; Koji Yamada; Masaki Mitani; Nobuo Kubota; Nobuyuki Kawakatsu; Kenichi Kishii; Masato Inazu; Yuji Kiuchi; Katsuji Oguchi; Takayuki Namiki
The novel diphenyl piperazine derivatives containing the phenyl substituted aminopropanol moiety, including 1-[4,4-bis(4-fluorophenyl)butyl]-4-[2-hydroxy-3-(phenylamino)propyl]piperazine 1, which were modified at the connective between the diphenyl and piperazine moieties, have been found to be potent dopamine uptake inhibitors. To study the further structure-activity relationship (SAR) of these compounds, a new series was synthesized, with modifications at the 2-hydroxy-3-phenylaminopropyl moiety of 1. The series was evaluated for dopamine transporter (DAT) binding affinity with [3H]GBR12935 in rat striatal membranes. Most of the compounds showed moderate to high DAT binding affinities and some were approximately equivalent in activity to compound 1 or GBR12909 as a dopamine uptake inhibitor, with IC(50) values of nanomolar range. The SAR suggested that on exhibiting a potent interaction with the DAT, there is probably a steric limitation around the benzene ring of the phenylamino moiety of 1, allowing only small-sized substituents with the exception of basic moieties at the 4-position. In addition, the SAR at the 3-amino-2-propanol moiety of 1 suggested that either the nitrogen atom with an electron donating substituent or the unsubstituted nitrogen atom and also the hydroxy group are desirable for elicitation of a potent DAT binding affinity.
Bioorganic & Medicinal Chemistry Letters | 2002
Makoto Kimura; Tomoko Masuda; Koji Yamada; Nobuo Kubota; Nobuyuki Kawakatsu; Masaki Mitani; Kenichi Kishii; Masato Inazu; Takayuki Namiki
Two types of novel diphenylalkyl piperazine derivatives containing the thio or aminopropanol moiety substituted by phenyl or benzyl group were synthesized, and evaluated for their calcium antagonistic and antioxidative activities. These compounds showed apparent inhibitions against KCl-induced contractions in isolated rat aorta. Among them, phenylamino compound 9 and benzylamino compound 13 also possessed potent inhibitory activities against auto-oxidative lipid peroxidations in canine brain homogenates. Two representative compounds 3a and 9 were evaluated for their inhibitory activities against KCl-induced contractions in isolated canine arteries (basilar, coronary, mesenteric, and renal). Both compounds showed the most potent inhibitions to basilar artery.
Bioorganic & Medicinal Chemistry | 2003
Makoto Kimura; Tomoko Masuda; Koji Yamada; Masaki Mitani; Nobuo Kubota; Nobuyuki Kawakatsu; Kenichi Kishii; Masato Inazu; Yuji Kiuchi; Katsuji Oguchi; Takayuki Namiki
A new series of diphenyl piperazine derivatives containing the phenyl substituted aminopropanol moiety, which were modified at sites between the diphenyl and piperazine moieties, was prepared and evaluated for dopamine transporter binding affinity with [(3)H]GBR12935 in rat striatal membranes. These synthesized compounds showed apparent dopamine transporter binding affinities (IC(50)<30 nM) and some of them were approximately equivalent in activity to GBR12909 known as a potent dopamine uptake inhibitor, showing the activities with IC(50) values of nanomolar range. Among them, 1-[4,4-bis(4-fluorophenyl)butyl]-4-[2-hydroxy-3-(phenylamino)propyl]piperazine 2 was evaluated for extracellular dopamine levels in rat striatum using in vivo brain microdialysis. The intraperitoneal administration of 2 (0.01, 0.03, or 0.1 mmol/kg) induced dose-dependent increases of dopamine levels in rat striatal dialysates. The maximum increases in dopamine levels induced by 2 were greater than those by GBR12909. The pharmacological data of these novel diphenyl piperazine derivatives show that the compounds have potent dopamine uptake inhibitory activities in the central nervous system.
Bioorganic & Medicinal Chemistry Letters | 2004
Makoto Kimura; Tomoko Masuda; Koji Yamada; Nobuyuki Kawakatsu; Nobuo Kubota; Masaki Mitani; Kenichi Kishii; Masato Inazu; Yuji Kiuchi; Katsuji Oguchi; Takayuki Namiki
Archive | 1998
Takayuki Namiki; Masayuki Yuasa; Takako Takakuwa; Satoshi Ichinomiya; Yukio Kawazu; Kenichi Kishii; Norio Funayama; Mariko Harada; Kyoko Taneda; Naoki Hiyama; Tomoaki Yahiro; Mayumi Sugio; Masashi Tamai
Archive | 1991
Masato Inazu; Yoshiyuki Miyata; Toshihiro Morimoto; Takeshi Yamamoto; Yuji Yoshiko; Kazunori Harada; Yoshiharu Momota; Masayuki Yanagi; Ryoko Yokota; Tetsuo Katoh; Takayuki Namiki; Makoto Kimura; Nobuyuki Kawakatsu
Archive | 2001
Naoki Hiyama; Satoshi Ichinomiya; Makoto Kimura; Kenichi Kishii; Tomoko Masuda; Masamiki Mitani; Takayuki Namiki; Masashi Tamai; 聡 一ノ宮; 昌幹 三谷; 隆之 並木; 智子 増田; 兼一 岸井; 誠 木村; 直樹 檜山; 将志 玉井
Archive | 1998
Takayuki Namiki; Masayuki Yuasa; Takako Takakuwa; Satoshi Ichinomiya; Yukio Kawazu; Kenichi Kishii; Norio Funayama; Mariko Harada; Kyoko Taneda; Naoki Hiyama; Tomoaki Yahiro; Mayumi Sugio; Masashi Tamai
Archive | 1997
Yoko Kawakatsu; Makoto Kimura; Takayuki Namiki; Koji Yamada; Masayuki Yanagi; 隆之 並木; 浩次 山田; 庸行 川勝; 誠 木村; 正行 柳
Archive | 1997
Yoko Kawakatsu; Makoto Kimura; Takayuki Namiki; Koji Yamada; Masayuki Yanagi; 隆之 並木; 浩次 山田; 庸行 川勝; 誠 木村; 正行 柳