Mamoru Koketsu

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Flavonoids are widely occurring polyphenols that are found in plants. The aim of this study was to investigate the structure–activity relationships of 5,7-dihydroxyflavones, with a focus on the effect of B ring structure substitution on the antiproliferative effects of the compounds in human leukemia HL-60 cells. We prepared a series of(More)
Free sialylglycans (FSGs) and a sialylglycopeptide (SGP) as components of hen's egg yolk were found and their chemical structures were determined. SGP and FSGs were isolated from fresh egg yolk by treatment with phenol, gel filtration and successive chromatographies on columns of anion- and cation-exchangers. They were localized in the yolk plasma. The(More)
We investigated the superoxide anion-scavenging effects of six selenocarbamates and four thiocarbamates, using a highly sensitive quantitative chemiluminescence method. At 333 nM, six selenocarbamates and four thiocarbamates scavenged in the range of 2.9-68.7% of O(2)*-. Se-methyl N-phenylselenocarbamate and Se-methyl N-(4-methylphenyl)selenocarbamate(More)
The inhibitory activities of 5,6-dihydro-4H-1,3-selenazine derivatives on protein kinases were investigated. In a multiple protein kinase assay using a postnuclear fraction of v-src-transformed NIH3T3 cells, 4-ethyl-4-hydroxy-2-p-tolyl-5, 6-dihydro-4H-1,3-selenazine (TS-2) and 4-hydroxy-6-isopropyl-4-methyl-2-p-tolyl-5,6-dihydro-4H-1, 3-selenazine (TS-4)(More)
Two unidentified soluble carbohydrates were isolated from chrysanthemum (Dendranthema x grandiflorum (Ramat.) Kitamura) leaves using HPLC. The compounds were identified as 1 L-chiro-inositol, called L-inositol (1) and scyllo-inositol, called scyllitol (2) from the results of 1H-NMR, 13C-NMR, and CI-MS spectra. L-Inositol and scyllitol were distributed in(More)
The antitermite (termiticidal and antifeedant) activity of Protium javanicum Burm. f. extract was investigated. The ethyl acetate fraction was active. Scopoletin (1), quercetin, and stigmasterol were isolated by bioassay-guided fractionation. Scopoletin had the highest activity among the three compounds. In order to investigate the structure-activity(More)
The extract of terrestrial alga Nostoc commune Vauch. has high antioxidative activity. Our study on N. commune Vauch. resulted in the isolation of two β-ionone derivatives, nostocionone and 3-oxo-β-ionone, together with four indole alkaloids, scytonemin, reduced scytonemin, N-(p-coumaroyl)tryptamine, and N-acetyltryptamine. The structures of the isolated(More)
In this study, we evaluated the in vitro cytotoxicity of fractions and isolated constituents from Cinnamomum parthenoxylon woods against human leukemia HL-60 and U937 cells. The n-Hex, EtOAc, and MeOH-H2O fractions of the woods inhibited cell proliferation in both cell lines. Our phytochemical investigation of the n-Hex and EtOAc fractions led to the(More)
The activation of extracellular receptor kinase (ERK) is one of the checkpoints to assess the activation of the classical Ras/mitogen-activated protein kinase (MAPK) cascade. Therefore, we tested more than 100 selenium-containing compounds for their ability to activate the MAPK signal pathway. Among them, we found that three selenazoles,(More)
Egg yolk, a large proportion of the egg, was studied for the preparation ofN-acetylneuraminic acid (Neu5Ac). The delipidated hen egg yolk (DEY; 500 kg containing 0.2% w/w, Neu5Ac) was hydrolysed with HCl (pH 1.4) at 80 °C and neutralized with NaOH (pH 6.0). The mixture was filtered and electrodialysed until the conductivity was 240 µS cm−1. The filtrate was(More)