Chiseko Sakuma

Learn More
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)
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)
Phytochemical analysis of the leaves of Cestrum nocturnum (Solanaceae) resulted in the isolation of two new flavonol glycosides (1, 2) and seven steroidal saponins (3-9), including four new ones (4, 6, 7, and 9). The structures of the new compounds were determined by spectroscopic analysis, including 2D NMR data, and the results of hydrolytic cleavage.(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)
Further phytochemical analysis aimed at the triterpene saponin constituents of the roots of Pulsatilla chinensis has resulted in the isolation of four new bisdesmosidic triterpene saponins whose aglycons are based on the lupane skeleton (1-4), together with three known saponins (5-7). The structures of the new compounds were determined by spectroscopic(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 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)
Phytochemical analysis of the underground parts of Polianthes tuberosa has resulted in the isolation of four new spirostanol saponins with five monosaccharides (1-4). Their structures were determined by spectroscopic analysis, including extensive 1D and 2D NMR data, and the results of hydrolytic cleavage. The cytotoxic activities of 1-4 against HL-60 human(More)
N-methyl-pyridinium formate, a novel component of coffee extracts, inhibited the multiplication of both DNA and RNA viruses. In the presence of the compound, the progeny viral yields of both herpes simplex virus type 1 (HSV-1) and poliovirus in HEp-2 cells and those of influenza virus type A in MDCK cells decreased with increasing concentrations of the(More)