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02/2012; , ISBN: 978-953-307-824-3
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ABSTRACT: Pd(0)-mediated rapid couplings of CH(3)I (and then [(11)C]CH(3)I) with excess 5-tributylstannyl-2'-deoxyuridine and -4'-thio-2'-deoxyuridine were investigated for the syntheses of [methyl-(11)C]thymidine and its stable analogue, 4'-[methyl-(11)C]thiothymidine as PET probes for cancer diagnosis. The previously reported conditions were attempted using Pd(2)(dba)(3)/P(o-CH(3)C(6)H(4))(3) (1 : 4 in molar ratio) at 130 °C for 5 min in DMF, giving desired products only in 32 and 30% yields. Therefore, we adapted the current reaction conditions developed in our laboratory for heteroaromatic compounds. The reaction using CH(3)I/stannane/Pd(2)(dba)(3)/P(o-CH(3)C(6)H(4))(3)/CuCl/K(2)CO(3) (1 : 25 : 1 : 32 : 2 : 5) at 80 °C gave thymidine in 85% yield. Whereas, CH(3)I/stannane/Pd(2)(dba)(3)/P(o-CH(3)C(6)H(4))(3)/CuBr/CsF (1 : 25 : 1 : 32 : 2 : 5) including another CuBr/CsF system promoted the reaction at a milder temperature (60 °C), giving thymidine in 100% yield. Chemo-response of thiothymidine-precursor was different from thymidine system. Thus, the above optimized conditions including CuBr/CsF system gave 4'-thiothymidine only in 40% yield. The reaction using 5-fold amount of CuBr/CsF at 80 °C gave much higher yield (83%), but unexpectedly, the reaction was accompanied by a considerable amount of undesired destannylated product. Such destannylation was greatly suppressed by changing to a CuCl/K(2)CO(3) system using CH(3)I/stannane/Pd(2)(dba)(3)/P(o-CH(3)C(6)H(4))(3)/CuCl/K(2)CO(3) (1 : 25 : 1 : 32 : 2 : 5) at 80 °C, giving the 4'-thiothymidine in 98% yield. The each optimized conditions were successfully applied to the syntheses of the corresponding PET probes in 87 and 93% HPLC analytical yields. [(11)C]Compounds were isolated by preparative HPLC after the reaction conducted under slightly improved conditions, exhibiting sufficient radioactivity of 3.7-3.8 GBq and specific radioactivity of 89-200 GBq µmol(-1) with radiochemical purity of ≥99.5% for animal and human PET studies.
Organic & Biomolecular Chemistry 06/2011; 9(11):4287-94. · 3.70 Impact Factor
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ABSTRACT: Dengue virus (DENV) is the etiologic agent for dengue fever, for which there is no approved vaccine or specific anti-viral drug. As a remedy for this, we explored the use of compounds that interfere with the action of required host factors and describe here the characterization of a kinase inhibitor (SFV785), which has selective effects on NTRK1 and MAPKAPK5 kinase activity, and anti-viral activity on Hepatitis C, DENV and yellow fever viruses. SFV785 inhibited DENV propagation without inhibiting DENV RNA synthesis or translation. The compound did not cause any changes in the cellular distribution of non-structural 3, a protein critical for DENV RNA synthesis, but altered the distribution of the structural envelope protein from a reticulate network to enlarged discrete vesicles, which altered the co-localization with the DENV replication complex. Ultrastructural electron microscopy analyses of DENV-infected SFV785-treated cells showed the presence of viral particles that were distinctly different from viable enveloped virions within enlarged ER cisternae. These viral particles were devoid of the dense nucleocapsid. The secretion of the viral particles was not inhibited by SFV785, however a reduction in the amount of secreted infectious virions, DENV RNA and capsid were observed. Collectively, these observations suggest that SFV785 inhibited the recruitment and assembly of the nucleocapsid in specific ER compartments during the DENV assembly process and hence the production of infectious DENV. SFV785 and derivative compounds could be useful biochemical probes to explore the DENV lifecycle and could also represent a new class of anti-virals.
PLoS ONE 01/2011; 6(8):e23246. · 4.09 Impact Factor
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Ryuki Kohta,
Yaichiro Kotake,
Takamitsu Hosoya,
Toshiyuki Hiramatsu,
Yuko Otsubo, Hiroko Koyama,
Yuji Hirokane,
Yuichi Yokoyama,
Hirofumi Ikeshoji,
Ken Oofusa,
Masaaki Suzuki,
Shigeru Ohta
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ABSTRACT: Substances that mimic the actions of causative gene products of familial Parkinson's disease (PD) are candidate as causative agents of idiopathic PD. 1-Benzyl-1,2,3,4-tetrahydroisoquinoline (1BnTIQ), an endogenous neurotoxin, is present at three times higher levels in CSF of PD patients than in CSF of control subjects. However, the mechanism of 1BnTIQ's neurotoxicity is unclear. In this study, we tried to identify 1BnTIQ-binding proteins by using a diazido-functionalized 1BnTIQ analog, 1-(3-azido-5-azidomethylbenzyl)-1,2,3,4-tetrahydroisoquinoline, designed and synthesized as a probe for radioisotope-free photoaffinity labeling. One major photolabeled protein identified using this probe was tubulin beta, which has been reported to be a substrate of parkin, a ubiquitin E3 ligase and a causative gene product of familial PD. Loss of function mutation of parkin is reported to result in loss of tubulin beta ubiquitination. Therefore, we examined the effect of 1BnTIQ on ubiquitination of tubulin beta. The polyubiquitinated tubulin beta level in human neuroblastoma SH-SY5Y cells was reduced in the presence of 1BnTIQ, even at concentrations as low as those detected in parkinsonian CSF. In vitro ubiquitination assay gave similar results. It is suggested that 1BnTIQ has the same effect on tubulin ubiquitination as does mutant parkin in familial PD. Taken together, substances which reduce polyubiquitination of tubulin such as 1BnTIQ are supposed to be candidates of etiological factors of PD.
Journal of Neurochemistry 09/2010; 114(5):1291-301. · 4.06 Impact Factor
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Ryuki Kohta,
Yaichiro Kotake,
Takamitsu Hosoya,
Toshiyuki Hiramatsu,
Yuko Otsubo, Hiroko Koyama,
Yuji Hirokane,
Yuichi Yokoyama,
Hirofumi Ikeshoji,
Ken Oofusa,
Masaaki Suzuki,
Shigeru Ohta
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ABSTRACT: J. Neurochem. (2010) 114, 1291–1301.AbstractSubstances that mimic the actions of causative gene products of familial Parkinson’s disease (PD) are candidate as causative agents of idiopathic PD. 1-Benzyl-1,2,3,4-tetrahydroisoquinoline (1BnTIQ), an endogenous neurotoxin, is present at three times higher levels in CSF of PD patients than in CSF of control subjects. However, the mechanism of 1BnTIQ’s neurotoxicity is unclear. In this study, we tried to identify 1BnTIQ-binding proteins by using a diazido-functionalized 1BnTIQ analog, 1-(3-azido-5-azidomethylbenzyl)-1,2,3,4-tetrahydroisoquinoline, designed and synthesized as a probe for radioisotope-free photoaffinity labeling. One major photolabeled protein identified using this probe was tubulin β, which has been reported to be a substrate of parkin, a ubiquitin E3 ligase and a causative gene product of familial PD. Loss of function mutation of parkin is reported to result in loss of tubulin β ubiquitination. Therefore, we examined the effect of 1BnTIQ on ubiquitination of tubulin β. The polyubiquitinated tubulin β level in human neuroblastoma SH-SY5Y cells was reduced in the presence of 1BnTIQ, even at concentrations as low as those detected in parkinsonian CSF. In vitro ubiquitination assay gave similar results. It is suggested that 1BnTIQ has the same effect on tubulin ubiquitination as does mutant parkin in familial PD. Taken together, substances which reduce polyubiquitination of tubulin such as 1BnTIQ are supposed to be candidates of etiological factors of PD.
Journal of Neurochemistry 01/2010; 114(5):1291 - 1301. · 4.06 Impact Factor
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ABSTRACT: The Pd(0)-mediated rapid trapping of methyl iodide with an excess amount of a heteroaryl-substituted tributylstannane has been investigated with the aim of incorporating a short-lived (11)C-labelled methyl group into the heteroaromatic carbon frameworks of important organic compounds, such as drugs with various heteroaromatic structures, in order to execute a positron emission tomography (PET) study of vital systems. The reaction was first performed by using our previously developed CH(3)I/stannane/[Pd(2)(dba)(3)]/P(o-CH(3)C(6)H(4))(3)/CuCl/K(2)CO(3) (1:40:0.5:2:2:2) system in DMF at 60 degrees C for 5 min (conditions A), however, the reaction gave low yields for various heteroaromatic compounds. Increasing the amount of phosphine ligand (conditions B) led to a significant improvement in the yield, but the conditions were still not suitable for a range of basic heteroaromatic structures. Use of the CuBr/CsF system (conditions C) also provided a result similar to that obtained under conditions B with an increased amount of the phosphine. Thus, pyridine and related heteroaromatic compounds remained less reactive substrates. The problem was overcome by replacing the DMF solvent with N-methyl-2-pyrolidinone (NMP). The reaction in NMP at 60-100 degrees C for 5 min using a CH(3)I/stannane/[Pd(2)(dba)(3)]/P(o-CH(3)C(6)H(4))(3)/CuBr/CsF (1:40:0.5:16:2:5) combination (conditions D) gave the methylated products in yields of more than 80 % (based on the reaction of CH(3)I) for all of the heteroaromatic compounds listed in this study. Thus, the combined use of NMP and an increased amount of phosphine is important for promoting the reaction efficiently. The use of this general approach to rapid methylation has been well demonstrated by the synthesis of the PET tracers 2- and 3-[(11)C]methylpyridines by using [Pd(2)(dba)(3)]/P(o-CH(3)C(6)H(4))(3)/CuBr/CsF (1:16:2:5) in NMP at 60 degrees C for 5 min, which gives the desired products in HPLC analytical yields of 88 and 91 %, respectively.
Chemistry 10/2009; 15(45):12489-95. · 5.93 Impact Factor
