- Synthesis of new carbon-11 labeled benzoxazole derivatives for PET imaging of 5-HT3 receptor
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5-HT3 receptor is an attractive target for the development of therapeutic agents for use in brain, heart and cancer diseases, and imaging agents for use in biomedical imaging technique PET. Benzoxazole derivatives are a novel class of 5-HT3 receptor partial agonists with high binding affinity. Carbon-11 labeled benzoxazole derivatives have been synthesized as new potential PET radioligands for imaging 5-HT3 receptor. The target tracers were prepared by N-[11C]methylation of their corresponding precursors using [11C]CH3OTf and isolated by HPLC purification procedure in 40-50% radiochemical yields, which were decay corrected to the end of bombardment (EOB), based on [11C]CO2. The overall synthesis time was 20-25 min from EOB. The radiochemical purity was >99%, and specific activity was in a range of 74-111 GBq/μmol at the end of synthesis (EOS).
- Gao, Mingzhang,Wang, Min,Hutchins, Gary D.,Zheng, Qi-Huang
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p. 1570 - 1574
(2008/09/21)
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- Regulatory molecules for the 5-HT3 receptor ion channel gating system
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Substituted benzoxazole derivatives which possess a nitrogen-containing heterocycle at C2 are selective partial agonists of the 5-HT3 receptor. Alteration of substituents on the benzoxazole nucleus affords both agonist-like and antagonist-like compounds, and uniquely modifies the function of the 5-HT3 receptor ion channel gating system. SAR and corroborative computational docking study for these partial agonists successfully explained structure and function of the 5-HT3 receptor.
- Yoshida, Satoshi,Watanabe, Takashi,Sato, Yasuo
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p. 3515 - 3523
(2008/02/07)
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- Antitumor agents. 5. Synthesis, structure - activity relationships, and biological evaluation of dimethyl-5H-pyridophenoxazin-5-ones, tetrahydro-5H-benzopyridophenoxazin-5-ones, and 5H-benzopyridophenoxazin-5-ones with potent antiproliferative activity
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New antiproliferative compounds, dimethyl-5H-pyrido[3,2-a]phenoxazin-5-ones (1-6), tetrahydro-5H-benzopyrido[2,3-j]phenoxazin-5-ones (7-9), and 5H-benzopyrido[3,2-a]phenoxazin-5-ones (10-12) were synthesized and evaluated against representative human neoplastic cell lines. Dimethyl derivatives 1-6 were more active against carcinoma than leukemia cell lines. The tetrahydrobenzo derivatives 7-9 were scarcely active, whereas the corresponding benzo derivatives 10-12 showed notable cytotoxicity against a majority of the tested cell lines. Molecular modeling studies indicated that the high potency of 10 and 11, the most cytotoxic compounds of the whole series, could be due to the position of the condensed benzene ring, which favors π-π stacking interactions with purine and pyrimidine bases in the DNA active site. Biological studies suggested that 10-12 have no effect on human topoisomerases I and II and that they induce arrest at the G2/M phase.
- Bolognese, Adele,Correale, Gaetano,Manfra, Michele,Lavecchia, Antonio,Novellino, Ettore,Pepe, Stefano
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p. 5110 - 5118
(2007/10/03)
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- Orally active benzoxazole derivative as 5-HT3 receptor partial agonist for treatment of diarrhea-predominant irritable bowel syndrome
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During our search for therapeutic agents to treat diarrhea-predominant IBS, we found that 2-substituted benzoxazole derivatives have a characteristic 5-HT3 receptor partial agonist activity with high affinity. Some of these compounds showed high in vitro metabolical stability, and 6g showed marked antidiarrhetic activity with little side effect of constipation in in vivo tests. Our results indicate that 5-HT3 receptor partial agonists might be superior as therapeutic agents to the drugs currently used for IBS treatment.
- Yoshida, Satoshi,Shiokawa, Sojiro,Kawano, Ken-Ichi,Ito, Tomoko,Murakami, Hiroshi,Suzuki, Hisashi,Sato, Yasuo
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p. 7075 - 7079
(2007/10/03)
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- Benzoxazole derivatives as novel 5-HT3 receptor partial agonists in the gut
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A series of benzoxazoles with a nitrogen-containing heterocyclic substituent at the 2-position was prepared and evaluated for 5-HT3 partial agonist activity on isolated guinea pig ileum. The nature of the substituent at the 5-position of the benzoxazole ring affected the potency for the 5-HTs receptor, and the 5-chloro derivatives showed increased potency and lowered intrinsic activity. 5-Chloro-7-methyl-2-(4-methyl-1- homopiperazinyl)benzoxazole (6v) exhibited a high binding affinity in the same range as that of the 5-HT3 antagonist granisetron, and its intrinsic activity was 12% of that of 5-HT. Compound 6v inhibited 5-HT-evoked diarrhea but did not prolong the transition time of glass beads in the normal distal colon even at a dose of 100 times the ED50 for diarrhea inhibition in mice. Compounds of this type are expected to be effective for the treatment of irritable bowel syndrome without the side effect of constipation.
- Sato, Yasuo,Yamada, Megumi,Yoshida, Satoshi,Soneda, Tomoko,Ishikawa, Midori,Nizato, Tetsutaro,Suzuki, Kokichi,Konno, Fukio
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p. 3015 - 3021
(2007/10/03)
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