Chiseko Sakuma

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A saponin-enriched fraction prepared from the MeOH extract of the roots of Clematis chinensis showed cytotoxic activity against HL-60 promyelocytic leukemia cells, from which five new triterpene saponins based on oleanolic acid, along with three known saponins, were isolated. The structures of the new saponins were determined on the basis of spectroscopic(More)
Internal acyl migration reactions of drug 1beta-O-acyl glucuronides are of interest because of their possible role in covalent binding to serum proteins and consequent allergic reactions as well as their influence on drug disposition. An approach using 13C labeling and nuclear magnetic resonance (NMR) spectroscopy has been used to investigate in situ the(More)
Antipyrine is a useful probe to evaluate variation of in vivo activities of oxidative hepatic drug-metabolizing enzymes. Here we describe a new approach using C labeling and NMR spectroscopy for the direct and simultaneous detection of all phase I and phase II metabolites of antipyrine in rat urine. [C-methyl-C]Antipyrine was synthesized and administered(More)
Pi in the medium relieved the toxicity of arsenate against cellular growth of Chlamydomonas reinhardtii. To investigate the relationship between intracellular P contents and arsenate resistance, we determined the intracellular P contents of arsenate-sensitive and arsenate-resistant mutants, which had been generated by random insertional mutagenesis. All 13(More)
The present investigation aimed at the glycoside constituents of the tubers of Eranthis cilicica has resulted in the isolation of two new bisdesmosidic triterpene saponins based upon hederagenin, named eranthisaponins A (1) and B (2), along with four known triterpene saponins. The structures of the new saponins 1 and 2 were determined on the basis of(More)
Thermal unfolding of ribonculease (RNase) T1 was studied by 1H nuclear Overhauser enhancement spectroscopy (NOESY) and 1H- 15N heteronuclear single-quantum coherence (HSQC) NMR spectroscopy at various temperatures. Native RNase T1 is a single-chain molecule of 104 amino acid residues, and has a single alpha-helix and two beta-sheets, A and B, which consist(More)
The structure of a new monomeric peptidoglycan-related compound with hypotensive and diuretic activities, cymbidine A (1) isolated from the orchid Cymbidium goeringii, was elucidated mainly by spectroscopic analysis. The structure of 1 was shown to involve four amino acids (D-alanin, meso-diaminopimelic acid, D-gultamic acid, and L-valine) and two amino(More)
The taste of black tea differs according to the different areas in which the tea is grown, even for the same species of tea. A combination of (1)H NMR spectroscopy and partial least-squares discriminate analysis (PLS-DA) was used to assess the quality differences of tea leaves from four cultivation areas with different elevations, RAN > 1800 m, UDA = 1200(More)
A new tracer technique, in which a 13C-labeled compound as a biological tracer and 13C nuclear magnetic resonance (NMR) as an analytical tool are used, is proposed. In order to verify the applicability of the method to clinical chemistry. [1-13C]benzoic acid was administered and [1'-13C]hippuric acid excreted in the urine was quantitated by NMR, by using(More)
Two novel triterpene bisdesmosides, designated as enterolosaponin A (1) and B (2), were isolated from Enterolobium contortisiliquum. The chemical structures of 1 and 2 were determined by analysis of their extensive spectroscopic data, as well as hydrolysis followed by chromatographic study. Enterolosaponins have a 2-amino-2-deoxy-D-glucosyl unit(More)