190 results on '"Murakami, Kei"'
Search Results
152. Cover Picture: Synthesis of Polybenzoacenes: Annulative Dimerization of Phenylene Triflate by Twofold C−H Activation (Angew. Chem. Int. Ed. 16/2020).
- Author
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Uryu, Mizuho, Hiraga, Taito, Koga, Yoshito, Saito, Yutaro, Murakami, Kei, and Itami, Kenichiro
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- *
DIMERIZATION , *MATERIALS science , *BORONIC esters - Published
- 2020
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153. Synthesis of N -β-brominated alkenyl isothiocyanates via dehydrogenation of alkyl isothiocyanates.
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Maeda B, Akiyoshi R, Tanaka D, Sato K, and Murakami K
- Abstract
This study presents a new dehydrogenative synthesis of alkenyl isothiocyanates, providing compounds with bromo and isothiocyanate groups. These reactive functionalities offer versatility for further transformations. Application in an amine sensor utilizing a coumarin-attached product demonstrates practical utility. This streamlined approach facilitates access to alkenyl isothiocyanates, valuable tools for biological studies.
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- 2024
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154. Functionalized Polyamine Synthesis with Photoredox Catalysis.
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Makihara Y, Maeda B, Akiyoshi R, Tanaka D, and Murakami K
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- Putrescine, Biological Transport, Spermine, Polyamines, Spermidine
- Abstract
Polyamines, such as putrescine and spermidine, are pivotal in various biological processes across living organisms. Despite their significance, structurally modified polyamines offer a less-explored avenue for discovering bioactive compounds. The limitation is attributed to the synthetic difficulty of accessing functionalized polyamines. In this study, we accomplished photoredox-catalyzed functionalization of polyamines to diversify their structure. The rapid functionalization allows attaching fluorophores to the target polyamine, facilitating the development of molecular probes for advancing chemical biology studies., (© 2024 Wiley-VCH GmbH.)
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- 2024
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155. Recent advancement in the synthesis of isothiocyanates.
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Maeda B and Murakami K
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Isothiocyanates exhibit various biological characteristics, including antimicrobial, anti-inflammatory, and anticancer properties. Their significance extends to synthetic chemistry, where they serve as valuable platforms for versatile transformations. Consequently, they have attracted the attention of biologists and chemists. This review summarizes recent advancements in the synthesis of isothiocyanates. Access to a variety of starting materials is important to prepare isothiocyanates with diverse structures. This review categorizes synthetic methods into three types based on the starting materials and functional groups: (i) type A, derived from primary amines; (ii) type B, derived from other nitrogen functional groups; and (iii) type C, derived from non-nitrogen groups. Recent trends in synthetic methods have revealed the prevalence of type-A reactions derived from primary amines. However, type B reactions have rarely been reported. Notably, over the past four years, there has been a notable increase in type C reactions, indicating a growing interest in non-nitrogen-derived isothiocyanates. Overall, this review not only outlines the advancements in the synthesis of isothiocyanates but also highlights trends in the methodology.
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- 2024
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156. Switchable Decarboxylation by Energy- or Electron-Transfer Photocatalysis.
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Sakakibara Y, Itami K, and Murakami K
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Kolbe dimerization and Hofer-Moest reactions are well-investigated carboxylic acid transformations, wherein new carbon-carbon and carbon-heteroatom bonds are constructed via electrochemical decarboxylation. These transformations can be switched by choosing an electrode that allows control of the reactive intermediate, such as carbon radical or carbocation. However, the requirement of a high current density diminishes the functional group compatibility with these electrochemical reactions. Here, we demonstrate the photocatalytic decarboxylative transformation of activated carboxylic acids in a switchable and functional group-compatible manner. We discovered that switching between Kolbe-type or Hofer-Moest-type reactions can be accomplished with suitable photocatalysts by controlling the reaction pathways: energy transfer (EnT) and single-electron transfer (SET). The EnT pathway promoted by an organo-photocatalyst yielded 1,2-diarylethane from arylacetic acids, whereas the ruthenium photoredox catalyst allows the construction of an ester scaffold with two arylmethyl moieties via the SET pathway. The resulting radical intermediates were coupled to olefins to realize multicomponent reactions. Consequently, four different products were selectively obtained from a simple carboxylic acid. This discovery offers new opportunities for selectively synthesizing multiple products via switchable reactions using identical substrates with minimal cost and effort.
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- 2024
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157. Copper-catalyzed reaction of aziridine for the synthesis of substituted imidazolidine and imidazolidinone.
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Hashimoto K, Higuchi D, Matsubara S, and Murakami K
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Herein we report a copper-catalyzed synthesis of imidazolidine by employing the reaction of aziridine with imine. The reaction smoothly provided a diverse range of 2-substituted imidazolidines with high compatibility with various functional groups. Moreover, during our investigation, we discovered that isocyanate also reacted with aziridine to yield substituted imidazolidinones efficiently. The versatility of these reactions was further demonstrated by their application in the synthesis of hybrid molecules derived from two pharmaceutical compounds. This approach opens new possibilities for the discovery of novel classes of bioactive molecules., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2023 Hashimoto, Higuchi, Matsubara and Murakami.)
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- 2023
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158. Copper-Catalyzed Heterocyclic Recombination of Aziridine and Diazetidine for the Synthesis of Imidazolidine.
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Higuchi D, Matsubara S, Kadowaki H, Tanaka D, and Murakami K
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The discovery of new catalytic applications for metals remains an important goal in organic synthesis. If a catalyst has multiple functions, such as inducing bond cleavage and formation, it can streamline multi-step transformations. Herein, the Cu-catalyzed synthesis of imidazolidine through heterocyclic recombination between aziridine and diazetidine is reported. Mechanistically, Cu catalyzes the conversion of diazetidine into the corresponding imine, which then reacts with aziridine to form imidazolidine. The scope is sufficiently wide to form various imidazolidines, as many functional groups are compatible with the reaction conditions., (© 2023 Wiley-VCH GmbH.)
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- 2023
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159. Divergent Synthesis of Stachyurin and Casuarinin Focusing on C-Glycosidic Bond Reactivity.
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Kusuki R, Murakami K, Katsuta R, Ishigami K, and Wakamori S
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- Humans, Phenols chemistry, Polyphenols, Hydrolyzable Tannins chemistry, Glucose
- Abstract
Stachyurin and casuarinin are ellagitannins, a class of polyphenols that exhibit various biological activities that have an impact on human health. Casuarinin is a stachyurin stereoisomer. These compounds contain the characteristic C-glycosidic bond between the open-chain d-glucose and the phenol aromatic ring. Therefore, chemical elucidation of the C-glycosidic bond reactivity is required to exploit their multiple bioactivities. This study developed a method for the divergent synthesis of stachyurin and casuarinin via the α-selective C-glycosylation as well as the β-selective introduction of the oxygen functional group, focusing on structural specificity. The proposed method applies to the syntheses of stachyurin and casuarinin analogues, thereby facilitating the utilisation of their beneficial bioactivities., (© 2023 Wiley-VCH GmbH.)
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- 2023
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160. Identification and improvement of isothiocyanate-based inhibitors on stomatal opening to act as drought tolerance-conferring agrochemicals.
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Aihara Y, Maeda B, Goto K, Takahashi K, Nomoto M, Toh S, Ye W, Toda Y, Uchida M, Asai E, Tada Y, Itami K, Sato A, Murakami K, and Kinoshita T
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- Light, Drought Resistance, Proton-Translocating ATPases metabolism, Isothiocyanates pharmacology, Isothiocyanates metabolism, Plant Stomata metabolism, Arabidopsis Proteins metabolism
- Abstract
Stomatal pores in the plant epidermis open and close to regulate gas exchange between leaves and the atmosphere. Upon light stimulation, the plasma membrane (PM) H
+ -ATPase is phosphorylated and activated via an intracellular signal transduction pathway in stomatal guard cells, providing a primary driving force for the opening movement. To uncover and manipulate this stomatal opening pathway, we screened a chemical library and identified benzyl isothiocyanate (BITC), a Brassicales-specific metabolite, as a potent stomatal-opening inhibitor that suppresses PM H+ -ATPase phosphorylation. We further developed BITC derivatives with multiple isothiocyanate groups (multi-ITCs), which demonstrate inhibitory activity on stomatal opening up to 66 times stronger, as well as a longer duration of the effect and negligible toxicity. The multi-ITC treatment inhibits plant leaf wilting in both short (1.5 h) and long-term (24 h) periods. Our research elucidates the biological function of BITC and its use as an agrochemical that confers drought tolerance on plants by suppressing stomatal opening., (© 2023. The Author(s).)- Published
- 2023
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161. Incidence of Mid-Term Prognostic Events in Patients With Acute Coronary Syndrome During the Late 2010s in 2 Tertiary Hospitals in a Rural Area of Japan - A Temporal Comparison.
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Yasuda Y, Ishiguchi H, Yamaguchi M, Murakami K, Kinoshita N, Kato T, Yoshida M, Imoto K, Sonoyama K, Kawabata T, Okamura T, Endo A, Kobayashi S, Yano M, Oda T, and Tanabe K
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Background: Data on the incidence of mid-term prognostic events in patients who developed acute coronary syndrome (ACS) in the late 2010s are scarce. Methods and Results: We retrospectively included and collected data for 889 patients with ACS (ST-elevation myocardial infarction [STEMI]/non-ST-elevation ACS [NSTE-ACS]) discharged alive from 2 tertiary hospitals in Izumo City, in rural Japan, between August 2009 and July 2018. Patients were divided into 3 time groups (T1: August 2009-July 2012; T2: August 2012-July 2015; T3: August 2015-July 2018). The cumulative incidence of major adverse cardiovascular events (MACE; comprising all-cause death, recurrent ACS, and stroke), major bleeding, and heart failure hospitalization within 2 years of discharge was compared among the 3 groups. The incidence of freedom from MACE was significantly higher in the T3 group than in the T1 and T2 groups (93 [95% confidence interval {CI} 90-96%] vs. 86% [95% CI 83-90] and 89% [95% CI 90-96], respectively; P=0.03). There was a tendency for a higher incidence of STEMI among patients in T3 (P=0.057). The incidence of NSTE-ACS was comparable among the 3 groups (P=0.31), as was the incidence of major bleeding and hospitalization for heart failure. Conclusions: The incidence of mid-term MACE in patients who developed ACS during the late 2010 s (2015-2018) was lower than that in prior periods (2009-2015)., Competing Interests: M. Yano, K.T. are members of Circulation Reports’ Editorial Board. The remaining authors have no conflicts of interest to declare., (Copyright © 2023, THE JAPANESE CIRCULATION SOCIETY.)
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- 2023
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162. Verification of Biaryl-Structure Axial Chirality Produced in Ellagitannins by Chemical Oxidation.
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Wakamori S, Osada R, Matsumoto S, Kusuki R, and Murakami K
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- Molecular Structure, Hydrolyzable Tannins, Glucose
- Abstract
The axial chirality of hexahydroxydiphenoyl (HHDP) groups contained in ellagitannins depends on the bridging position of d-glucose. The 4,6- O -HHDP group predominantly exhibits S- type chirality. This study elucidated the formation of the 4,6- O -( R )-HHDP group and subsequent axial isomerization by means of oxidative coupling of galloyl groups, which resulted in S chirality.
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- 2022
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163. Photoinduced Synthesis of Thiocyanates through Hydrogen Atom Transfer and One-Pot Derivatization to Isothiocyanates.
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Maeda B, Aihara Y, Sato A, Kinoshita T, and Murakami K
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- Isothiocyanates, Oxidants, Pharmaceutical Preparations, Hydrogen, Thiocyanates
- Abstract
Photoinduced benzylic C-H thiocyanation is described. A series of alkyl thiocyanates were efficiently obtained by using Selectfluor as the oxidant. Moreover, we accomplished the one-pot isothiocyanation following the C-H thiocyanation. The thiocyanates and isothiocyanates were applied to the divergent transformation of pharmaceuticals.
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- 2022
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164. Central nervous system stimulants promote nerve cell death under continuous hypoxia.
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Ikeda-Murakami K, Ikeda T, Watanabe M, Tani N, and Ishikawa T
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- Caffeine adverse effects, Cell Death, Cell Hypoxia physiology, Humans, Hypoxia pathology, Neurons metabolism, Brain Edema pathology, Central Nervous System Stimulants adverse effects
- Abstract
Intake of central nervous system (CNS) stimulants causes hypoxia and brain edema, which results in nerve cell death. However, no study has yet investigated the direct and continuous effects on nerve cells of CNS stimulants under hypoxia. Thus, based on autopsy cases, the effects of CNS stimulant drugs on the CNS were examined. The pathological changes in cultured nerve cells when various CNS stimulants were added under a hypoxic condition were also investigated. Five groups (Group A, stimulants; Group B, stimulants with psychiatric drugs; Group C, caffeine; Group D, psychiatric drugs; and Group E, no drugs) according to the detected drugs in autopsy cases were compared, and brain edema was evaluated using morphological findings. Furthermore, the number of dead cultured nerve cells was counted after the addition of drugs (4-aminopyridine (4-AP), caffeine, and ephedrine) under hypoxia (3% O2). Staining with anti-receptor-interacting protein 3 (RIP3) and other associated stains was also performed to investigate the neuronal changes in the brain. Group A showed significantly more brain edema than the other groups. In the culture experiments, the ratio of nerve cell death after the addition of 4-AP was the highest in the hypoxic condition. Groups with stimulants detected were stained more strongly by RIP3 immunostaining than by other staining. Addition of stimulants to cultured nerve cells in a persistent hypoxic condition led to severe cytotoxicity and nerve cell death. These findings suggest that necroptosis is involved in nerve cell death due to the addition of CNS stimulants in the hypoxic condition., (© 2022. The Author(s) under exclusive licence to Japan Human Cell Society.)
- Published
- 2022
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165. Ultrasonic cleaning is effective in removing carbonized clots and tissue from the insulation-tipped diathermic knife-2.
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Murakami K, Hirata D, Haraguchi K, Arai N, Inoue K, Miyazaki Y, Funase K, Nakashige T, Teramoto A, Iwatate M, Hattori S, Fujita M, Sano W, and Sano Y
- Abstract
Objectives: Since carbonized clots and tissue (debris) tend to adhere firmly to the tip of the endoscopic submucosal dissection (ESD) knife as the procedure proceeds, manual removing the firm debris is often challenging and time-consuming. Recently, effective ultrasonic cleaning for other medical devices has been reported. The aim of the present study was to clarify whether ultrasonic cleaning is effective in removing the debris on the insulation-tipped diathermic (IT) knife-2., Methods: This study was an ex-vivo experimental randomized study. A total of 40 IT knife-2 knives with debris on their tip surfaces were prepared and randomly assigned to two groups (Group A and Group B). The knives in Group A were cleaned using the conventional scrubbing method for 30 s (conventional cleaning method), while those in Group B were cleaned using a combined method of scrubbing for 20 s and ultrasonic cleaning for 10 s (combined ultrasonic cleaning method). The tip electrode of the knife after cleaning was photographed under a microscope (40x). The 40 images of the knives were evaluated by independent three endoscopists and two clinical engineers using the five-step evaluation criteria ranging from cleaning score 1 (dirty) to 5 (clean)., Results: The mean cleaning score of 3.78 (range: 2.33-4.67) in Group B was significantly higher than that of 1.68 (range: 1.00-2.83) in Group A., Conclusions: The combined ultrasonic cleaning method could remove debris adhering to the IT knife-2 more effectively than the conventional cleaning method. Ultrasonic cleaning may be applied for real-world ESD., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors. DEN Open published by John Wiley & Sons Australia, Ltd on behalf of Japan Gastroenterological Endoscopy Society.)
- Published
- 2022
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166. Central Nervous System Stimulants Limit Caffeine Transport at the Blood-Cerebrospinal Fluid Barrier.
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Ikeda-Murakami K, Tani N, Ikeda T, Aoki Y, and Ishikawa T
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- Autopsy, Biological Transport, Blood-Brain Barrier chemistry, Case-Control Studies, Cells, Cultured, Choroid Plexus cytology, Endothelial Cells chemistry, Endothelial Cells cytology, Endothelium, Vascular cytology, Humans, Models, Biological, 4-Aminopyridine pharmacology, Caffeine pharmacokinetics, Central Nervous System Stimulants pharmacology, Cerebrospinal Fluid chemistry, Choroid Plexus chemistry, Endothelium, Vascular chemistry
- Abstract
Caffeine, a common ingredient in energy drinks, crosses the blood-brain barrier easily, but the kinetics of caffeine across the blood-cerebrospinal fluid barrier (BCSFB) has not been investigated. Therefore, 127 autopsy cases (Group A, 30 patients, stimulant-detected group; and Group B, 97 patients, no stimulant detected group) were examined. In addition, a BCSFB model was constructed using human vascular endothelial cells and human choroid plexus epithelial cells separated by a filter, and the kinetics of caffeine in the BCSFB and the effects of 4-aminopyridine (4-AP), a neuroexcitatory agent, were studied. Caffeine concentrations in right heart blood (Rs) and cerebrospinal fluid (CSF) were compared in the autopsy cases: caffeine concentrations were higher in Rs than CSF in Group A compared to Group B. In the BCSFB model, caffeine and 4-AP were added to the upper layer, and the concentration in the lower layer of choroid plexus epithelial cells was measured. The CSF caffeine concentration was suppressed, depending on the 4-AP concentration. Histomorphological examination suggested that choroid plexus epithelial cells were involved in inhibiting the efflux of caffeine to the CSF. Thus, the simultaneous presence of stimulants and caffeine inhibits caffeine transfer across the BCSFB.
- Published
- 2022
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167. C-H Acyloxylation of Polycyclic Aromatic Hydrocarbons.
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Sakakibara Y, Murakami K, and Itami K
- Abstract
The C-H acyloxylation of polycyclic aromatic hydrocarbons (PAHs) is described. This reaction constructs aryl acyloxylate scaffolds from PAHs with equimolar hypervalent iodine compounds under mild reaction conditions. Interestingly, the blue light irradiation accelerated this transformation. Additionally, the synthesis of structurally new symmetric and unsymmetric diaroyloxylated fluoranthenes was accomplished with a ruthenium photoredox catalyst.
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- 2022
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168. Identification of stomatal-regulating molecules from de novo arylamine collection through aromatic C-H amination.
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Toda Y, Perry GJP, Inoue S, Ito E, Kawakami T, Narouz MR, Takahashi K, Aihara Y, Maeda B, Kinoshita T, Itami K, and Murakami K
- Abstract
Stomata-small pores generally found on the leaves of plants-control gas exchange between plant and the atmosphere. Elucidating the mechanism that underlies such control through the regulation of stomatal opening/closing is important to understand how plants regulate photosynthesis and tolerate against drought. However, up-to-date, molecular components and their function involved in stomatal regulation are not fully understood. We challenged such problem through a chemical genetic approach by isolating and characterizing synthetic molecules that influence stomatal movement. Here, we describe that a small chemical collection, prepared during the development of C-H amination reactions, lead to the discovery of a Stomata Influencing Molecule (SIM); namely, a sulfonimidated oxazole that inhibits stomatal opening. The starting molecule SIM1 was initially isolated from screening of compounds that inhibit light induced opening of dayflower stomata. A range of SIM molecules were rapidly accessed using our state-of-the-art C-H amination technologies. This enabled an efficient structure-activity relationship (SAR) study, culminating in the discovery of a sulfonamidated oxazole derivative (SIM*) having higher activity and enhanced specificity against stomatal regulation. Biological assay results have shed some light on the mode of action of SIM molecules within the cell, which may ultimately lead to drought tolerance-conferring agrochemicals through the control of stomatal movement., (© 2022. The Author(s).)
- Published
- 2022
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169. Synthesis of octagon-containing molecular nanocarbons.
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González Miera G, Matsubara S, Kono H, Murakami K, and Itami K
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Nanocarbons, such as fullerenes, carbon nanotubes, and graphenes, have long inspired the scientific community. In order to synthesize nanocarbon molecules in an atomically precise fashion, many synthetic reactions have been developed. The ultimate challenge for synthetic chemists in nanocarbon science is the creation of periodic three-dimensional (3D) carbon crystals. In 1991, Mackay and Terrones proposed periodic 3D carbon crystals with negative Gaussian curvatures that consist of six- and eight-membered rings (the so-called Mackay-Terrones crystals). The existence of the eight-membered rings causes a warped nanocarbon structure. The Mackay-Terrones crystals are considered a "dream material", and have been predicted to exhibit extraordinary mechanical, magnetic, and optoelectronic properties (harder than diamond, for example). To turn the dream of having this wonder material into reality, the development of methods enabling the creation of octagon-embedding polycyclic structures (or nanographenes) is of fundamental and practical importance. This review describes the most vibrant synthetic achievements that the scientific community has performed to obtain curved polycyclic nanocarbons with eight-membered rings, building blocks that could potentially give access as templates to larger nanographenes, and eventually to Mackay-Terrones crystals, by structural expansion strategies., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)
- Published
- 2021
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170. Discovery of bactericides as an acute mitochondrial membrane damage inducer.
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Houston R, Sekine Y, Larsen MB, Murakami K, Mullett SJ, Wendell SG, Narendra DP, Chen BB, and Sekine S
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- Biguanides pharmacology, Chlorhexidine pharmacology, Drug Evaluation, Preclinical methods, HeLa Cells, Homeostasis, Humans, Membranes metabolism, Metalloendopeptidases drug effects, Metalloendopeptidases genetics, Metalloendopeptidases metabolism, Mitochondria drug effects, Mitochondria metabolism, Mitochondrial Proteins metabolism, Phospholipids metabolism, Anti-Bacterial Agents pharmacology, Mitochondrial Membranes drug effects, Mitochondrial Membranes metabolism
- Abstract
Mitochondria evolved from endosymbiotic bacteria to become essential organelles of eukaryotic cells. The unique lipid composition and structure of mitochondrial membranes are critical for the proper functioning of mitochondria. However, stress responses that help maintain the mitochondrial membrane integrity are not well understood. One reason for this lack of insight is the absence of efficient tools to specifically damage mitochondrial membranes. Here, through a compound screen, we found that two bis-biguanide compounds, chlorhexidine and alexidine, modified the activity of the inner mitochondrial membrane (IMM)-resident protease OMA1 by altering the integrity of the IMM. These compounds are well-known bactericides whose mechanism of action has centered on their damage-inducing activity on bacterial membranes. We found alexidine binds to the IMM likely through the electrostatic interaction driven by the membrane potential as well as an affinity for anionic phospholipids. Electron microscopic analysis revealed that alexidine severely perturbated the cristae structure. Notably, alexidine evoked a specific transcriptional/proteostasis signature that was not induced by other typical mitochondrial stressors, highlighting the unique property of alexidine as a novel mitochondrial membrane stressor. Our findings provide a chemical-biological tool that should enable the delineation of mitochondrial stress-signaling pathways required to maintain the mitochondrial membrane homeostasis.
- Published
- 2021
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171. Clinical effectiveness of implant support for distal extension removable partial dentures: functional evaluation using occlusal force measurement and masticatory efficiency.
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Murakami K, Ayukawa Y, Ogino Y, Nakagawa A, Horikawa T, Yamaguchi E, Takaki K, and Koyano K
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- Bite Force, Denture, Partial, Humans, Mastication, Treatment Outcome, Denture, Partial, Removable
- Abstract
Background: Implant-supported removable partial dentures (ISRPD) are supported at the free-end region with implant retainers. As implant retainers prevent denture settlement and facilitate denture retention, this is intended to improve masticatory performance in comparison with that of conventional removable dentures. In the present study, we evaluated the effect of implant retainers at the free-end region of removable dentures on occlusal force and masticatory efficiency using a pressure-sensitive sheet, and measured glucose concentration in saliva after mastication with gummy candy., Methods: In the present study, the occlusal force and masticatory efficiency of 13 subjects were measured in the following three conditions: without dentures (Condition 1), wearing dentures but not supported by implants (Condition 2), and wearing dentures supported by implants (ISRPD) (Condition 3). All data were statistically compared., Results: Regarding the occlusal force, Condition 3 showed significantly higher scores than the other conditions; however, there were no significant differences between Conditions 1 and 2. Regarding the masticatory efficiency, Condition 3 showed significantly higher scores than Condition 2., Conclusions: With ISRPD, the occlusal force and masticatory efficiency were increased in comparison with those with conventional removable dentures., (© 2021. The Author(s).)
- Published
- 2021
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172. Photoredox-Catalyzed Benzylic Esterification via Radical-Polar Crossover.
- Author
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Maeda B, Sakakibara Y, Murakami K, and Itami K
- Abstract
Photoredox-catalyzed C-O bond formation reactions are reported. The decarboxylative esterification reaction allows the conversion of a variety of arylacetic acids into the corresponding benzyl carboxylates. Furthermore, the use of (diacetoxyiodo)benzene allows the conversion of the benzylic C-H bond through hydrogen atom transfer. The reactions were applied to the divergent transformation of pharmaceuticals via decarboxylative or C-H esterification reactions.
- Published
- 2021
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173. Morphologies of Vesicle Doublets: Competition among Bending Elasticity, Surface Tension, and Adhesion.
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Murakami K, Ebihara R, Kono T, Chiba T, Sakuma Y, Ziherl P, and Imai M
- Subjects
- Elasticity, Surface Tension, Temperature, Models, Biological
- Abstract
To study the mechanical laws governing the form of multicellular organisms, we examine the morphology of adhering vesicle doublets as the simplest model system. We monitor the morphological transformations of doublets induced by changes of adhesion strength and volume/area ratio, which are controlled by intermembrane interactions and thermal area expansion, respectively. When we increase the temperature in the weak adhesion regime, a dumbbell flat-contact doublet is transformed to a parallel-prolate doublet, whereas in the strong adhesion regime, heating transforms the dumbbell flat-contact doublet into a spherical sigmoid-contact doublet. We reproduce the observed doublet morphologies by numerically minimizing the total energy, including the contact-potential adhesion term as well as the surface and bending terms, using the Surface Evolver package. From the reproduced morphologies, we extract the adhesion strength, the surface tension, and the volume/area ratio of the vesicles, which reveals the detailed mechanisms of the morphological transitions in doublets., (Copyright © 2020 Biophysical Society. Published by Elsevier Inc. All rights reserved.)
- Published
- 2020
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174. Synthesis of Polybenzoacenes: Annulative Dimerization of Phenylene Triflate by Twofold C-H Activation.
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Uryu M, Hiraga T, Koga Y, Saito Y, Murakami K, and Itami K
- Abstract
Polycyclic aromatic hydrocarbons (PAHs) represent an emerging class of π-conjugated molecules in the area of optoelectronic devices and materials. Unprecedented synthetic routes to various PAHs from simple phenol derivatives by a palladium-catalyzed annulative dimerization of phenylene triflate through twofold inter- and intramolecular C-H activation have been established. The initially formed partially fused PAHs can be smoothly transformed into a variety of fully fused PAHs by the Scholl reaction. Furthermore, the reactions of phenanthrene-substituted aryl triflates proceeded regioselectively. The findings inspired the development of a rapid and efficient synthesis of polybenzoacene derivatives. This study not only allows transformation of phenyl triflates, but also discloses a new retrosynthetic strategy towards PAHs, especially polybenzoacenes., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2020
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175. Rapid Access to Kinase Inhibitor Pharmacophores by Regioselective C-H Arylation of Thieno[2,3- d ]pyrimidine.
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Yamada S, Flesch KN, Murakami K, and Itami K
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- Catalysis, Molecular Structure, Palladium chemistry, Protein Kinase Inhibitors chemistry, Pyrimidines chemistry, Stereoisomerism, Protein Kinase Inhibitors chemical synthesis, Pyrimidines chemical synthesis
- Abstract
Regioselective C-H arylations of thieno[2,3- d ]pyrimidine are accomplished under palladium catalysis. Thieno[2,3- d ]pyrimidines react with aryl iodides at the C6-position and with aryl boronic acids at the C5-position, showing excellent regioselectivity. Mechanistic investigations indicate that the regioselectivity is controlled by the nature of the palladium catalyst: the cationic palladium favorably arylates the C5-position. The utility of this direct arylation has been highlighted in the streamlined synthesis of kinase inhibitors and their derivatives.
- Published
- 2020
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176. Dehydrogenative Synthesis of 2,2'-Bipyridyls through Regioselective Pyridine Dimerization.
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Yamada S, Kaneda T, Steib P, Murakami K, and Itami K
- Abstract
2,2'-Bipyridyls have been utilized as indispensable ligands in metal-catalyzed reactions. The most streamlined approach for the synthesis of 2,2'-bipyridyls is the dehydrogenative dimerization of unfunctionalized pyridine. Herein, we report on the palladium-catalyzed dehydrogenative synthesis of 2,2'-bipyridyl derivatives. The Pd catalysis effectively works with an Ag
I salt as the oxidant in the presence of pivalic acid. A variety of pyridines regioselectively react at the C2-positions. This dimerization method is applicable for challenging substrates such as sterically hindered 3-substituted pyridines, where the pyridines regioselectively react at the C2-position. This reaction enables the concise synthesis of twisted 3,3'-disubstituted-2,2'-bipyridyls as an underdeveloped class of ligands., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)- Published
- 2019
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177. Sigmatropic Dearomatization/Defluorination Strategy for C-F Transformation: Synthesis of Fluorinated Benzofurans from Polyfluorophenols.
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Okamoto K, Hori M, Yanagi T, Murakami K, Nogi K, and Yorimitsu H
- Abstract
Facile synthesis of fluorinated benzofurans from polyfluorophenols has been accomplished by means of a sigmatropic dearomatization/defluorination strategy composed of three processes: (1) interrupted Pummerer reaction of ketene dithioacetal monoxides with polyfluorophenols followed by [3,3] sigmatropic rearrangement, (2) Zn-mediated smooth reductive removal of fluoride from the dearomatized intermediate, and (3) acid-promoted cyclization/aromatization. Mechanistic investigations revealed important characteristic reactivity of polyfluorophenols in the present system. Some of the fluorinated benzofuran products were transformed by utilizing the 2-methylsulfanyl moieties., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2018
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178. Synthesis of partially and fully fused polyaromatics by annulative chlorophenylene dimerization.
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Koga Y, Kaneda T, Saito Y, Murakami K, and Itami K
- Abstract
Since the discovery by Ullmann and Bielecki in 1901, reductive dimerization (or homocoupling) of aryl halides has been extensively exploited for the generation of a range of biaryl-based functional molecules. In contrast to the single-point connection in these products, edge-sharing fused aromatic systems have not generally been accessible from simple aryl halides via annulation cascades. Here we report a single-step synthesis of fused aromatics with a triphenylene core by the palladium-catalyzed annulative dimerization of structurally and functionally diverse chlorophenylenes through double carbon-hydrogen bond activation. The partially fused polyaromatics can be transformed into fully fused, small graphene nanoribbons, which are otherwise difficult to synthesize. This simple, yet powerful, method allows access to functional π-systems of interest in optoelectronics research., (Copyright © 2018, The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
- Published
- 2018
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179. Clinical Factors That Affect the Establishment of Soft Tissue Sarcoma Patient-Derived Orthotopic Xenografts: A University of California, Los Angeles, Sarcoma Program Prospective Clinical Trial.
- Author
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Russell TA, Eckardt MA, Murakami T, Elliott IA, Kawaguchi K, Kiyuna T, Igarashi K, Li Y, Crompton JG, Graham DS, Dry SM, Bernthal N, Yanagawa J, Kalbasi A, Federman N, Chmielowski B, Singh AS, Hoffman RM, and Eilber FC
- Abstract
Purpose: Given the diverse and aggressive nature of soft tissue sarcomas (STSs), a need exists for more-precise therapy. Patient-derived orthotopic xenografts (PDOXs) provide a unique platform for personalized treatment. Thus, identification of patient and treatment factors that predict PDOX establishment is important. This study assessed the feasibility of incorporating PDOXs into the clinical setting and identifying factors associated with PDOX establishment., Patients and Methods: From May 2015 to May 2016, 107 patients with biopsy-proven or potential STS were enrolled. Tumor samples were obtained intraoperatively and orthotopically implanted into nude mice in the corresponding anatomic location. PDOXs were considered established after engraftment and serial passage. Factors associated with establishment were analyzed by logistic regression and time to establishment by time-to-event analysis., Results: Only high-grade tumors established (32 of 72 [44.4%]). The establishment rate (ER) varied by neoadjuvant therapy and treatment response, with the highest ER among untreated high-grade tumors (26 of 42 [61.9%]). Tumors exposed to radiation preoperatively did not establish (zero of 11 [0%]), and tumors exposed to neoadjuvant chemotherapy had a lower ER(31.9%) than untreated tumors. Only STSs with minimal pathologic response to neoadjuvant treatment (≤ 30%) established a PDOX (six of 18 [33.3%]). Median establishment time was 54 days, which varied by neoadjuvant therapy but was not statistically significant ( P = .180)., Conclusion: To our knowledge, in the largest STS PDOX study to date, we demonstrate a 62% ER among untreated high-grade tumors with a median establishment time of 54 days. Neoadjuvant therapy, particularly radiation, and pathologic response to treatment were associated with a reduced rate of PDOX establishment., Competing Interests: AUTHORS’ DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The following represents disclosure information provided by authors of this manuscript. All relationships are considered compensated. Relationships are self-held unless noted. I = Immediate Family Member, Inst = My Institution. Relationships may not relate to the subject matter of this manuscript. For more information about ASCO’s conflict of interest policy, please refer to www.asco.org/rwc or po.ascopubs.org/site/ifc. Tara A. Russell No relationship to disclose Mark A. Eckardt No relationship to disclose Takashi Murakami No relationship to disclose Irmina A. Elliott No relationship to disclose Kei Kawaguchi No relationship to disclose Tasuku Kiyuna No relationship to disclose Kentaro Igarashi No relationship to disclose Yungfeng Li No relationship to disclose Joseph G. Crompton No relationship to disclose Danielle S. Graham Stock and Other Ownership Interests: DaVita (I) Sarah M. Dry No relationship to disclose Nicholas Bernthal Honoraria: Daiichi Sankyo Consulting or Advisory Role: Onkos Surgical, Bonesupport Research Funding: Onkos Surgical Jane Yanagawa No relationship to disclose Anusha Kalbasi No relationship to disclose Noah Federman Stock and Other Ownership Interests: Genmab, Kite Pharma Consulting or Advisory Role: Zelda Therapeutics Bartosz Chmielowski Consulting or Advisory Role: Amgen, Bristol-Myers Squibb, Merck, Genentech, Roche, Eisai, Immunocore Speakers’ Bureau: Genentech, Roche, Janssen Pharmaceuticals Travel, Accommodations, Expenses: Genentech, Roche, Bristol-Myers Squibb, Janssen Pharmaceuticals, Merck Arun S. Singh Consulting or Advisory Role: Eli Lilly, Daiichi Sankyo Speakers’ Bureau: Eli Lilly, Eisai Travel, Accommodations, Expenses: Eli Lilly, Daiichi Sankyo, Eisai Stock and Other Ownership Interests: AntiCancer-PDOX Robert M. Hoffman Stock and Other Ownership Interests: AntiCancer-PDOX Fritz C. Eilber Stock and Other Ownership Interests: AntiCancer-PDOX
- Published
- 2017
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180. Transition-Metal-Free Synthesis of Carbazoles and Indoles by an SN Ar-Based "Aromatic Metamorphosis" of Thiaarenes.
- Author
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Bhanuchandra M, Murakami K, Vasu D, Yorimitsu H, and Osuka A
- Subjects
- Catalysis, Electrons, Molecular Structure, Aniline Compounds chemistry, Carbazoles chemical synthesis, Heterocyclic Compounds chemistry, Indoles chemical synthesis, Metals chemistry, Thiophenes chemistry
- Abstract
Dibenzothiophene dioxides, which are readily prepared through oxidation of the parent dibenzothiophenes, undergo nucleophilic aromatic substitution with anilines intermolecularly and then intramolecularly to yield the corresponding carbazoles in a single operation. The "aromatic metamorphosis" of dibenzothiophenes into carbazoles does not require any heavy metals. This strategy is also applicable to the synthesis of indoles. Since electron-deficient thiaarene dioxides exhibit interesting reactivity, which is not observed for that the corresponding electron-rich azaarenes, a combination of a thiaarene-dioxide-specific reaction with the SN Ar-based aromatic metamorphosis allows transition-metal-free construction of difficult-to-prepare carbazoles., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2015
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181. Activator-free palladium-catalyzed silylation of aryl chlorides with silylsilatranes.
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Yamamoto Y, Matsubara H, Murakami K, Yorimitsu H, and Osuka A
- Abstract
The palladium-catalyzed silylation of aryl chlorides with silylsilatranes proceeds under activator-free conditions; hence, wide functional group compatibility is displayed and boryl and siloxy groups are able to survive. Experimental and computational studies revealed that smooth transmetalation from the silylsilatrane to the arylpalladium chloride is facilitated by strong interaction between the Lewis acidic silicon and the chloride., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2015
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182. Palladium-catalyzed cross-coupling of unactivated aryl sulfides with arylzinc reagents under mild conditions.
- Author
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Otsuka S, Fujino D, Murakami K, Yorimitsu H, and Osuka A
- Abstract
Cross-coupling of general aryl alkyl sulfides with arylzinc reagents proceeds smoothly, even at room temperature or below, with a palladium-N-heterocyclic carbene (NHC) catalyst. When combined with reactions that are unique to organosulfurs, that is, the SNAr sulfanylation or Pummerer reaction, the cross-coupling offers interesting transformations that are otherwise difficult to achieve. An alkylsulfanyl group is preferentially converted whilst leaving the tosyloxy and chloro intact, which expands the variety of orthogonal cross-coupling., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2014
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183. Practical, modular, and general synthesis of benzofurans through extended Pummerer annulation/cross-coupling strategy.
- Author
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Murakami K, Yorimitsu H, and Osuka A
- Subjects
- Benzofurans chemistry, Catalysis, Benzofurans chemical synthesis
- Abstract
Operationally simple, efficient, and widely applicable Pummerer annulations of simple phenols with ketene dithioacetal monoxides, with the aid of trifluoroacetic anhydride, have been shown to provide a variety of benzofurans having a methylthio group at the 2-position. Subsequent and newly developed nickel-catalyzed arylation at the methylthio group culminates in diversity-oriented synthesis of multisubstituted benzofurans. Our extended Pummerer annulation/cross-coupling sequence is powerful enough to synthesize biologically active natural products as well as highly fluorescent benzofuran derivatives., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
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- 2014
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184. Clinical significance of CYLD downregulation in breast cancer.
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Hayashi M, Jono H, Shinriki S, Nakamura T, Guo J, Sueta A, Tomiguchi M, Fujiwara S, Yamamoto-Ibusuki M, Murakami K, Yamashita S, Yamamoto Y, Li JD, Iwase H, and Ando Y
- Subjects
- Adult, Aged, Aged, 80 and over, Cell Line, Tumor, Deubiquitinating Enzyme CYLD, Disease-Free Survival, Female, Gene Expression Regulation, Neoplastic, Humans, Middle Aged, RANK Ligand metabolism, Triple Negative Breast Neoplasms pathology, beta Catenin genetics, NF-kappa B genetics, Signal Transduction genetics, Triple Negative Breast Neoplasms genetics, Tumor Suppressor Proteins biosynthesis
- Abstract
Cylindromatosis (CYLD) is a tumor suppressor gene that is mutated in familial cylindromatosis, a rare autosomal dominant disorder associated with numerous benign skin adnexal tumors. CYLD is now known to regulate various signaling pathways, including transforming growth factor-β signaling, Wnt/β-catenin signaling, and NF-κB signaling by deubiquitinating upstream regulatory factors. Downregulation of CYLD has been reported in several malignancies; however, the clinical significance of CYLD expression in many malignancies, including breast cancer, remains to be elucidated. This study investigated the clinical significance of CYLD in breast cancer and its roles in tumor progression. We evaluated CYLD expression in matched normal breast tissue samples and tumor breast tissue samples from 26 patients with breast cancer and in a series of breast cancer cell lines. In addition, by means of immunohistochemistry, we investigated CYLD protein expression and its clinical significance in 244 breast cancer cases. We also analyzed the effects of CYLD repression or overexpression on breast cancer cell viability, cell migration, and NF-κB activity with or without receptor activator of NF-κB ligand (RANKL) stimulation. Breast cancer tissues demonstrated significantly reduced CYLD mRNA expression compared with normal breast tissues. Downregulation of CYLD promoted cell survival and migratory activities through NF-κB activation, whereas CYLD overexpression inhibited those activities in MDA-MB-231 cells. As an important finding, CYLD overexpression also inhibited RANKL-induced NF-κB activation. Our immunohistochemical analysis revealed that reduced CYLD protein expression was significantly correlated with estrogen receptor negativity, high Ki-67 index, high nuclear grade, decreased disease-free survival, and reduced breast cancer-specific survival in primary breast cancer. Moreover, reduced CYLD expression was an independent factor for poor prognosis in breast cancer. CYLD downregulation may promote breast cancer metastasis via NF-κB activation, including RANKL signaling.
- Published
- 2014
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185. Demetalation of metal porphyrins via magnesium porphyrins by reaction with Grignard reagents.
- Author
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Murakami K, Yamamoto Y, Yorimitsu H, and Osuka A
- Subjects
- Indicators and Reagents, Coordination Complexes chemistry, Magnesium chemistry, Porphyrins chemistry
- Published
- 2013
- Full Text
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186. Copper-catalyzed extended Pummerer reactions of ketene dithioacetal monoxides with alkynyl sulfides and ynamides with an accompanying oxygen rearrangement.
- Author
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Murakami K, Imoto J, Matsubara H, Yoshida S, Yorimitsu H, and Oshima K
- Subjects
- Catalysis, Molecular Structure, Alkynes chemistry, Copper chemistry, Ethylenes chemistry, Ketones chemistry, Oxygen chemistry, Sulfides chemistry, Sulfoxides chemistry
- Abstract
The first examples of metal-catalyzed extended Pummerer reactions through the activation of sulfoxides are described. The copper-catalyzed reactions of ketene dithioacetal monoxides with alkynyl sulfides and ynamides provided a wide variety of γ,γ-disulfanyl-β,γ-unsaturated carbonyl compounds with an accompanying oxygen rearrangement. The products can be easily converted into 1,4-dicarbonyl compounds and substituted heteroaromatics. DFT calculations and mechanistic experiments revealed a new interesting stepwise addition/oxygen rearrangement mechanism., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2013
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187. A general approach to the basiliolide/transtaganolide natural products: total syntheses of basiliolide B, epi-8-basiliolide B, transtaganolide C, and transtaganolide D.
- Author
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Nelson HM, Murakami K, Virgil SC, and Stoltz BM
- Subjects
- Artemisinins chemistry, Crystallography, X-Ray, Molecular Conformation, Pyrones chemistry, Stereoisomerism, Artemisinins chemical synthesis, Pyrones chemical synthesis
- Published
- 2011
- Full Text
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188. Cobalt-catalyzed benzylzincation of alkynes.
- Author
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Murakami K, Yorimitsu H, and Oshima K
- Published
- 2010
- Full Text
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189. Cobalt-catalyzed arylzincation of alkynes.
- Author
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Murakami K, Yorimitsu H, and Oshima K
- Abstract
Cobalt(II) bromide catalyzes arylzincation of alkynes with arylzinc iodide x lithium chloride complexes in acetonitrile. The scope of the arylzincation is wide enough to use unfunctionalized alkynes, such as 6-dodecyne, as well as arylacetylenes. The inherent functional group compatibility of arylzinc reagents allows preparation of various functionalized styrene derivatives. The reaction is applicable to the efficient and stereoselective synthesis of a synthetic estrogen and its derivative.
- Published
- 2009
- Full Text
- View/download PDF
190. Chromium-catalyzed arylmagnesiation of alkynes.
- Author
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Murakami K, Ohmiya H, Yorimitsu H, and Oshima K
- Abstract
[reaction: see text] Arylmagnesiation of unfunctionalized alkynes in the presence of catalytic amounts of chromium(II) chloride and pivalic acid proceeds with high stereoselectivity. The alkenylmagnesium intermediate reacts with various electrophiles to afford the corresponding tetrasubstituted olefins in good yields.
- Published
- 2007
- Full Text
- View/download PDF
Catalog
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