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61.
H Harada K Iizuka T Kamijo K Akahane R Yamamoto Y Nakano A Tsubaki T Kubota I Shimaoka H Umeyama 《Chemical & pharmaceutical bulletin》1990,38(11):3042-3047
The experimental details for the synthesis of human renin inhibitors are described. In order to avoid metabolic degradation of the Phe-His (P3-P2) amide bond in transition-state analogs, structurally modified acyl residues (P4-P3) were incorporated into the inhibitors. Compound 1a, which contained 2-(1-naphthylmethyl)-3-(N-phenethylcarbamoyl)propionyl residue (P4-P3) with a retro-inverso amide bond, L-histidine, and norstatine isoamylamide residue (P1-P1) as a transition-state mimic, had potent human renin inhibitory activity, and it lowered blood pressure when administered orally to common marmosets. 相似文献
62.
Kubota Y Nelson JK Perticone D Poling R Schrenk S Crawford G Fulton R Jensen T Johnson DR Kagan H Kass R Malchow R Morrow F Whitmore J Wilson P Bortoletto D Brown D Dominick J McIlwain RL Miller DH Modesitt M Ng CR Schaffner SF Shibata EI Shipsey IP Battle M Kroha H Sparks K Thorndike EH Wang C Alam MS Kim IJ Li WC Nemati B Romero V Sun CR Wang P Zoeller MM Goldberg M Haupt T Horwitz N Jain V Mestayer MD Moneti GC Rozen Y Rubin P Skwarnicki T Stone S Thusalidas M Yao W Zhu G Barnes AV Bartelt J 《Physical review D: Particles and fields》1991,44(3):593-600
63.
High concentrations of arsenic were observed in the blubber of ringed seals (Pusa hispida) in our previous study. To better understand the arsenic accumulation in blubber of marine mammals, arsenicals in the blubber of ringed seal were characterized using high performance liquid chromatography–inductively coupled plasma mass spectrometry (HPLC–ICPMS). The most predominant water-soluble arsenical in the blubber was dimethylarsinic acid (DMA), in spite of the predominance of arsenobetaine in other tissues. Lipid-soluble fraction was hydrolyzed under mild (tetraethylammonium hydroxide (TEAH) hydrolysis) and strong (NaOH hydrolysis) conditions, and then an aliquot of hydrolysate was injected onto HPLC–ICPMS. Both TEAH-labile and TEAH-stable/NaOH-labile lipid-soluble fractions contained precursors of DMA. These results suggest that the blubber might be the pool of DMA and DMA-containing precursors in ringed seals. 相似文献
64.
Four 6-phenyl-5,6,7,8-tetrahydro-4H-1,3,2,6-dioxathiazocine 2-oxides were synthesized by the reaction of the corresponding N,N-bis(2-hydroxyethyl)aniline with thionyl chloride in the presence of triethylamine. 相似文献
65.
Antonio S. Santos Arnaldo C. Pereira Maria D. P. T. Sotomayor César R. T. Tarley Nelson Durán Lauro T. Kubota 《Electroanalysis》2007,19(5):549-554
This work evaluated an amperometric biosensor based on multi‐wall carbon nanotubes (MWCNT), chemically modified with methylene blue (Met) and horseradish peroxidase (HRP), for detection of phenolic compounds. The dependences of the biosensor response due to the enzyme immobilization procedure, HRP amounts, pH and working potential were investigated. The amperometric response for catechol using the proposed biosensor showed a very wide linear response range (1 to 150 μmol L?1), good sensitivity (50 nA cm?2 μmol?1 L), excellent operational stability (after 300 determinations the response remained at 97%) and very good storage stability (lifetime>3 months). Based on all these characteristics, it is possible to affirm that the material is promising for phenol detection due to its good electrochemical response and enzyme stabilization. The biosensor response for various phenolic compounds was investigated. 相似文献
66.
Yoshitaka Ogiwara Yuji Kimura Zenjiro Osawa Hitoshi Kubota 《Journal of polymer science. Part A, Polymer chemistry》1977,15(7):1667-1675
Effects of ferric chloride (FeCl3) on photodegradation of high-density polyethylene (PE) were investigated by using ESR and infrared spectrometry. In the system with irradiation at light of λ > 220 nm, PE irradiated at 77°K yielded an 8-line spectrum, the intensity of which was markedly weakened by using FeCl3 with the sample, indicating a distinct depression of radical formation. On the other hand, PE with the use of FeCl3 yielded radicals under irradiation only with light of λ > 300 nm, showing a singlet spectrum with a line width of 15 gauss. For photooxidized PE, almost the same effect of FeCl3 was observed. On irradiation at room temperature, PE samples with and without FeCl3 showed a singlet spectrum with line widths of 15 and 25 gauss, respectively. On the other hand, the unsaturated double bond contained in a small amount in PE sample was observed by infrared study to be decreased with photoirradiation; however, the decrease was sharply depressed with the addition of FeCl3 to the sample. The degradation of carbonyl group in a photooxidized sample was markedly affected by photoirradiation, and the decay was obviously reduced for the sample on addition of FeCl3. It is concluded that FeCl3 works upon photodegradation of PE to enhance the Norrish type II reaction and to accelerate the formation of unsaturated double bond in the chain. 相似文献
67.
Kosaka T Yoneyama-Takazawa T Kubota K Matsuoka T Sato I Sasaki T Tanaka Y 《Journal of mass spectrometry : JMS》2003,38(12):1281-1287
We have developed a method for protein identification with peptide mass fingerprinting and sequence tagging using nano liquid chromatography (LC)/Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). To achieve greater sensitivity, a nanoelectrospray (nano-ES) needle packed with reversed-phase medium was used and connected to the nano-ES ion source of the FTICR mass spectrometer. To obtain peptide sequence tag information, infrared multiphoton dissociation (IRMPD) was carried out in nano-LC/FTICR-MS analysis. The analysis involves alternating nano-ES/FTICR-MS and nano-ES/IRMPD-FTICR-MS scans during a single LC run, which provides sets of parent and fragment ion masses of the proteolytic digest. The utility of this alternating-scan nano-LC/IRMPD-FTICR-MS approach was evaluated by using bovine serum albumin as a standard protein. We applied this approach to the protein identification of rat liver diacetyl-reducing enzyme. It was demonstrated that this enzyme was correctly identified as 3-alpha-hydroxysteroid dehydrogenase by the alternating-scan nano-LC/IRMPD-FTICR-MS approach with accurate peptide mass fingerprinting and peptide sequence tagging. 相似文献
68.
Hideaki Takahashi Shin-ichiro Kurimoto Junichi Kobayashi Takaaki Kubota 《Tetrahedron letters》2018,59(51):4500-4502
A new indole alkaloid with the canthin-6-one skeleton, ishigadine A, has been isolated from an Okinawan marine sponge Hyrtios sp. The structure of ishigadine A was elucidated on the basis of spectroscopic analyses. Ishigadine A is a new canthin-6-one alkaloid possessing a hydroxy group, a 1,3-dimethyl-4-methylthioimidazolium, and a 1-propylguanidine. Ishigadine A is the third canthin-6-one alkaloid from sponges. Ishigadine A might be generated from l-arginine, l-histidine, and l-tryptophan. Ishigadine A exhibited moderate cytotoxicity against L1210 murine leukemia cells. 相似文献
69.
Total Synthesis of the 7,10‐Epimer of the Proposed Structure of Amphidinolide N,Part II: Synthesis of C17–C29 Subunit and Completion of the Synthesis
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Dr. Koji Ochiai Dr. Sankar Kuppusamy Yusuke Yasui Kenji Harada Dr. Nishant R. Gupta Dr. Yohei Takahashi Prof. Dr. Takaaki Kubota Prof. Dr. Jun'ichi Kobayashi Prof. Dr. Yujiro Hayashi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(10):3287-3291
The total synthesis of 7,10‐epimer of the proposed structure of amphidinolide N was accomplished. The requisite chiral C17–C29 subunit was assembled stereoselectively via Keck allylation, Shi epoxidation, diastereoselective 1,3‐reduction, and a later oxidative synthesis of the THF framework. The C1–C13 and C17–C29 subunits were successfully coupled using a Enders RAMP “linchpin” as the C14–C16 three carbon unit, thereby controlling the chirality at C14 and C16. The labile allyl epoxy moiety was successfully constructed by Grieco–Nishizawa olefination at a final stage of the synthesis. 相似文献
70.
The radiation-induced polymerization of ethyl vinyl ether was studied in n-pentane and neopentane solutions under super-dry conditions. The free ion yields of these solvents are reported to be 0.16 and 1.0, respectively. The rate of polymerization in neopentane was about twice as fast as in n-pentane. The dose-rate dependence of the rate of polymerization was found to be nearly 0.50 in both solutions. It seems clear that the free solvent ions do, indeed contribute to the initiation. Regenerative chain transfer to monomer played a more important role in n-pentane than in neopentane as revealed by the molecular weight of the polymers. 相似文献