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41.
Nguyen Van Chuyen Tadao Kurata Hiromichi Kato Masao Fujimaki 《Bioscience, biotechnology, and biochemistry》2013,77(4):971-978
The organic solvent extract of Kumazasa leaves (Sasa albo-marginata) showed antimicrobial activity against bacteria, fungi and yeast. Kumazasa at a concentration of 0.2-1.0% showed stronger antimicrobial activity than potassium sorbate or sodium benzoate at the same concentration. Both acidic and phenolic fractions of the extract showed strong antimicrobial activity. Thirty acidic and phenolic compounds were identified by GC and GC-MS analysis. Acetic, propionic, benzoic, phenylacetic, salicylic, 3-hydroxybenzoic and o-anisic acids, and guaiacol, phenol, 4-ethylphenol, xylenol and 4-vinylphenol were the main components. It was estimated that these components play an important role in the formation of the antimicrobial activity of Kumazasa extract. 相似文献
42.
43.
Hiromichi Nagasawa Akira Isogai Akinori Suzuki Saburo Tamura 《Bioscience, biotechnology, and biochemistry》2013,77(8):1759-1763
13C-NMR spectra of isoechinulins A, B and C, metabolites from Aspergillus ruber, were fully assigned on the basis of chemical shifts and multiplicities and comparison with their analogues. Taking advantage of the symmetrical structure of the diketopiperazine ring, the stereochemistry of the trisubstituted carbon-carbon double bond in a dehydrotryptophyl moiety was determined as Z (cis) by measuring the coupling constants, , in the proton nondecoupled spectrum of isoechinulin B. 相似文献
44.
Takeshi Sugai Hiromichi Ohta Sadao Yoshikawa 《Bioscience, biotechnology, and biochemistry》2013,77(6):1579-1580
Chemical modification of tryptophan residues in abrin-a with N-bromosuccinimide (NBS) was studied with regard to saccharide-binding. The number of tryptophan residues available for NBS oxidation increased with lowering pH, and 11 out of the 13 tryptophan residues in abrin-a were eventually modified with NBS at pH 4.0, while 6 tryptophan residues were modified at pH 6.0 in the absence of specific saccharides. Modification of tryptophan residues at pH 6.0 greatly decreased the saccharide-binding ability of abrin-a, and only 2% of the hemagglutinating activity was retained after modification of 3 residues/mol. When the modification was done in the presence of lactose or galactose, 1 out of 3 residues/mol remained unmodified with a retention of a fairly high hemagglutinating activity. However, GalNAc did not show such a protective effect. NBS-oxidation led to a great loss of the fluorescence of abrin-a, and after modification of 3 tryptophan residues/mol, the fluorescence intensity at 345 nm was only 38% of that of the unmodified abrin-a. The binding of lactose to abrin-a altered the environment of the tryptophan residue at the saccharide-binding site of abrin-a, leading to a blue shift of the fluorescence spectrum. The ability to generate such fluorescence spectroscopic changes induced by lactose-binding was retained in the derivative in which 2 tryptophan residues/mol were oxidized in the presence of lactose, but not in the derivative in which 3 tryptophan residues/mol were oxidized in the absence of lactose. Importance of the tryptophan residue(s) in the saccharide-binding of abrin-a is suggested. 相似文献
45.
Hiromichi Kato 《Bioscience, biotechnology, and biochemistry》2013,77(6):551-554
N-d-Glucosyl-p-aminobenzoic acid has been found to form melanoidins in methanol solution acidified with hydrogen chloride at 25°. From the reaction mixture 5-hydroxymethyl-furfural (HMF) has been isolated and identified as its 2,4-dinitrophenylhydrazone. So, comparisons between the browning reaction of HMF or furfural with aromatic amine and that of the corresponding n-glycosides have been made under the same condition. From the results obtained, it has been shown that, under the described condition, furfural is almost inactive for browning, while on the contrary, HMF is active and plays an important role in the browning reaction. 相似文献
46.
Soichi Arai Makoto Abe Michiko Yamashita Hiromichi Kato Masao Fujimaki 《Bioscience, biotechnology, and biochemistry》2013,77(4):552-559
An indole derivative having blue fluorescence was produced in cooked soybean digested at 37°C for 24 hr with an acid proteinase Molsin (optimum pH: 2.8) from Aspergillus saitoi or a usual acid proteinase pepsin (optimum pH: 1.6) from beef stomach. This indole derivative was identical with a condensation product from l-tryptophan and n-hexanal. Based on MS, NMR, IR and UV spectrometry, the condensation product was identified as l-pentyl-2, 3, 4, 9-tetrahydro-lH-pyrido [3, 4-b]-indole-3-carboxylic acid [trivial name: 1-pentyl-l, 2, 3, 4-tetrahydro-2-carboline carboxylic acid-(3)].Data were presented of the formation of the above indole derivative and of the resulting consumption of l-tryptophan and n-hexanal.The possible ocurrence of the formation of Harmala alkaloids, i.e. 2-carboline derivatives, through in vitro digestion of soybean with acid proteinases was discussed.A carbonyl-trapping ability of l-tryptophan was suggested. 相似文献
47.
Soichi Arai Masatoshi Noguchi Michiko Yamashita Hiromichi Kato Masao Fujimaki 《Bioscience, biotechnology, and biochemistry》2013,77(9):1338-1345
Soy proteins were incubated with a microbial acid protease (Molsin) under the following condition: substrate concentration, 1%; enzyme-substrate ratio (by weight), 1/100; pH, 2.8; and temperature, 40°C—flavor components and related impurities are removable from crude soy-protein concentrates by their incubation for 2 hr under the above condition. The acid-precipitated fraction of soy protein incubated for 2 hr with Molsin (i.e. 2 hr-proteolyzate) showed the following composition: 10% trichloroacetic acid (TCA) insoluble fraction, 47.52%; 10% TCA soluble peptide fraction, 52.02%; and free amino acid fraction, 0.46%. Gel filtration of the 2 hr-proteolyzate gave an elution pattern showing its molecular weight distribution.In the process of the incubation of the acid-precipitated protein, the 10% TCA insoluble fraction showed increase in amino nitrogen content, its solubility in a phosphate buffer increased to change at 6 hr, and a hydrophobic amino acid share in this fraction increased gradually.In vitro digestibility of the acid-precipitated fraction were improved and the lipoxygenase activity in this fraction decreased through the Molsin treatment.Ultracentrifugal analysis showed a decreasing tendency of the cold-insoluble fraction of soy protein during its incubation with Molsin. Optical rotatory dispersion and circular dichroism study elucidated conformational changes in this fraction during its incubation either with or without Molsin. 相似文献
48.
Masao Fujimaki Makio Morita Hajime Kashio Hiromichi Kato 《Bioscience, biotechnology, and biochemistry》2013,77(12):2323-2327
The effects of γ-irradiation on the antioxidative activity developing in the amino acid-sugar reaction were investigated. The antioxidative activity of the nondialyzable melanoidin prepared from glycine and d-glucose was not much affected by γ-irradiation. However, the development of the antioxidative activity of an l-leucine-d-glucose solution on heating was markedly accelerated when the mixture had been preirradiated with γ-rays, and the development of the activity was more prominent than that of the brown color. The irradiation of a glucose solution alone accelerated the antioxidative activity development when heated with leucine, but the irradiation of a leucine solution alone did not cause a similar effect when heated with glucose. Except an l-cysteine-glucose combination, all combinations of amino acids and sugars tested gave rise to almost similar antioxidative effects. 相似文献
49.
Norimasa Kirigaya Hiromichi Kato Masao Fujimaki 《Bioscience, biotechnology, and biochemistry》2013,77(3):287-290
A mixture of 0.8 M D-xylose and 0.8 M glycine, when heated at 100°C, showed inhibitory effect against autoxidation of 40% ethanol solution of linoleic acid. The antioxidant activity increased in proportion to color intensity of browning reaction solution, whereas reductones formed during the browning process showed little contribution to the activity. Nondialyzable melanoidin fraction of browning solution also showed a positive activity. Consequently, it was considered that melanoidin pigment would play an important role in the antioxidant activity. 相似文献
50.
Hiromichi Kato Mitsuyoshi Yamamoto Masao Fujimaki 《Bioscience, biotechnology, and biochemistry》2013,77(6):939-948
Degradation mechanisms of d-fructose by the interaction with amino acids or organic acids in aqueous solution at initial pH 5.5 heated at 100°C were investigated and a substantial difference in mechanisms between fructose degradation and glucose-glycine reaction was presented. d-Fructose browned more intensely than did d-glucose in lower concentration of glycine and/or in earier stage of reaction period. By catalytic action of carboxylate anions without any condensation with amino groups, d-fructose was decomposed to 3-deoxy-d-erythrohexosulose, 5-(hydroxymelhyl)-2-furaldehyde, and a less amount of pyruval-dehyde through caramelization. It was considered that the main path of fructose degradation was 1,2-enolization but 2,3-enolization would also occur to a little extent. 相似文献