Yuji Yamaguchi

Gifu University, Gihu, Gifu, Japan

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Publications (15)19.41 Total impact

  • Yuji Yamaguchi · Mamoru Koketsu
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    ABSTRACT: An active substance with high hyaluronidase inhibitory effect was isolated from the edible cyanobacterium Nostochopsis lobatus MAC0804NAN strain and characterized. The active component in the hot water extract was purified by anion exchange and gel filtration chromatography and was found to be a polysaccharide. The IC50 against hyaluronidase of the purified polysaccharide was 7.18 μg/ml whose inhibitory activity is 14.5 times stronger than that of disodium cromoglycate (DSCG), an anti-allergy medication. The carbohydrate composition which was analyzed by GC-MS and NMR was found to be composed mainly of glucose, glucuronic acid, fucose, 2-O-methylfucose, mannose, galactose and xylose. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.
    No preview · Article · Aug 2015 · Journal of Bioscience and Bioengineering
  • Yuki Kato · Masayuki Ninomiya · Yuji Yamaguchi · Mamoru Koketsu
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    ABSTRACT: Hyaluronidase is one of the most important enzymes in the development of many diseases. In this study, a series of xyloside analogues bearing a triazole and tetrazole at the anomeric position were prepared from xylosylthioureas and evaluated their inhibitory effects on the hyaluronidase. Triazole and tetrazole skeletons were formed via the Hg(OAc)2-mediated desulfurizative cyclization through carbodiimide intermediates. According to in vitro anti-hyaluronidase assay, tetrazole-xylosides having p-chloro- or p-nitro-substitution exhibited the high inhibition rates, whereas the compound having p-trifluoromethyl group on the structure did not show the potency. Our results demonstrated the importance of tetrazole-xylosides as hyaluronidase inhibitors.
    No preview · Article · Mar 2015 · Medicinal Chemistry Research
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    ABSTRACT: Cyanobacteria contain substances of high biological value and are used to meet the high demands of the global food and pharmaceutical industries. In this study, we prepared a hot water extract of the edible cyanobacterium, Nostochopsis, and evaluated its possible use as an ingredient in cosmetics. Specifically, a hot water extract of Nostochopsis was assayed for tyrosinase inhibitory activity. Tyrosinase, a key enzyme in skin melanin synthesis, was strongly inhibited by the Nostochopsis hot water extract, which reduced a-melanocyte-stimulating hormone-induced melanin synthesis in B16 mouse melanoma cells. Thus, Nostochopsis hot water extract may be suitable as an ingredient in cosmetics.
    No preview · Article · Mar 2014 · Food Science and Technology Research
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    Hiroyuki Takenaka · Yuji Yamaguchi
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    ABSTRACT: Worldwide, cyanobacteria (mainly Spirulina and Nostoc) are being commercially cultivated for food and feed. Different cultivation systems such as open ponds and closed photobioreactors are currently being used for commercial large-scale cultivation of phototrophs (cyanobacteria and other microalgae). This chapter provides overviews of open ponds and closed photobioreactors, with reference to the large-scale culturing of Spirulina and Nostoc. Selecting a suitable method for cyanobacterial production requires a comparison of the capabilities of open ponds such as raceway ponds, and photobioreactors.
    Full-text · Chapter · Feb 2014
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    ABSTRACT: Vitamin B 12 contents in the edible cyanobacterium Nostoc flagelliforme, also known as hair vegetable, were as-sayed using a microbiological method. We detected high vitamin B 12 contents in samples of naturally grown cells (109.2 ± 18.5 μg/100g dry weight) and cultured cells (120.2 ± 53.6 μg/100g dry weight). However, commercially available hair vegetable samples, which comprised fake substitutes and Nostoc, had variable contents (4.8 -101.6 μg/100g dry weight) because concomitant fake items contain very low vitamin B 12 contents. To evaluate whether natural and cultured N. flagelliforme samples contained vitamin B 12 or pseudovitamin B 12 , corrinoid compounds were purified and identified as pseudovitamin B 12 (approximately 72%) and vitamin B 12 (approximately 28%) using silica gel 60 TLC bioautography and LC/MS. The results suggested that N. flagelliforme contains substan-tial amounts of pseudovitamin B 12 , which is inactive in humans.
    Full-text · Article · Jan 2014 · Food and Nutrition Sciences
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    ABSTRACT: Nostoc commune is a terrestrial benthic blue-green alga that often forms an extended mucilaginous layer on the soil, accumulates on stones and mud in aquatic environments. Reduced-scytonemin (R-scy), isolated from N. commune Vaucher, has been shown to suppress the human T-lymphoid Jurkat cell growth. To reveal the mechanisms underlying the R-scy-mediated inhibition of Jurkat cell growth, we examined cell morphology, DNA fragmentation, and microtubule-associated-protein light chain 3 (LC3) modification in these cells. We observed multiple vacuoles as well as the conversion of LC3-I to LC3-II in R-scy-treated cells. These results suggest that the R-scy induced Jurkat cell growth inhibition is attributable to the induction of type II programmed cell death (PCD II; autophagic cell death or autophagy). We further examined the mechanisms underlying R-scy-induced PCDII. The cells treated with R-scy produced large amounts of reactive oxygen species (ROS), leading to the induction of mitochondrial dysfunction. However, the elimination of R-scy-induced ROS by treatment with N-acetyl-L-cysteine (NAC) markedly opposed R-scy-induced PCDII. Based on these results, we conclude that ROS formation plays a critical role in R-scy-induced PCDII.
    Full-text · Article · Jul 2013 · Food and chemical toxicology: an international journal published for the British Industrial Biological Research Association
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    ABSTRACT: Vitamin B(12) content of an edible cyanobacterium, Nostochopsis sp. was determined to be 140.6±16.2 μg/100 g dry weight by a microbiological method. To evaluate whether the Nostochopsis cells contain vitamin B(12) or inactive corrinoid compounds, corrinoid compounds were purified from the cells and then identified as pseudovitamin B(12) (97.4±11.8 μg/100 g dry weight) and vitamin B(12) (43.2±6.0 μg/100 g dry weight) on the basis of silica gel 60 TLC bioautograms and LC/ESI-MS/MS chromatograms. Vitamin B(12) content was significantly increased in the Nostochopsis cells (254.8±17.6 μg/100 g dry weight) grown in the vitamin B(12)-supplemented medium.
    Full-text · Article · Sep 2012 · Journal of Nutritional Science and Vitaminology
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    ABSTRACT: Phycobiliproteins were purified and characterized from an edible cyanobacterium, Nostochopsis sp. C-phycocyanin and allophycocyanin were simultaneously purified by about 3.9- and 4.3-fold to provide yields of 23 and 29%, respectively, from cell extracts using simple purification steps, such as ammonium sulfate fractionation and anion exchange chromatography. The purified preparation was eluted as a single peak with an apparent molecular mass of 117.0 kDa during a gel filtration. Polyacrylamide gel electrophoresis of the purified preparation yielded a single protein band in the absence of SDS, but in the presence of SDS, three protein bands with apparent molecular masses of 18.5, 16.5 and 15.5 kDa were formed. These results suggest that the purified preparation consists of C-phycocyanin and allophycocyanin, both of which were strongly associated with one another during purification. Furthermore, the purified Nostochopsis preparation (1 mg.mL(-1)) showed considerable antioxidant capacity (11.6 mu mol.L-1 trolox equivalent), which was similar to that (10.5 mu mol.L-1 trolox equivalent) of Spirulina C-phycocyanin.
    No preview · Article · May 2012 · Food Science and Technology Research
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    Setsuko Sakaki · Yuji Yamaguchi · Yuko Tsuya · Hiroyuki Takenaka
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    ABSTRACT: The inhibitory effect of edible microalga, Nostochopsis sp. on the activation of hyaluronidase was evaluated. The 50% inhibitory concentration (IC50) of the aqueous extract and the ethanol-insoluble fraction of aqueous extract was 0.0148 and 0.0178 mg/mL, respectively. The IC50 of disodium cromoglycate (DSCG) used as the anti-allergic medicine was 0.120 mg/mL. The IC50 of Nostochopsis sp. was 8 times smaller than that of DSCG. The aqueous extract was ultrafiltered through a membrane having a molecular exclusion limit of 10 kDa. The IC50 of the residue was almost the same as that of aqueous extract. These results suggest that Nostochopsis sp. might have strong anti-allergic substance(s) which may be polysaccharides.
    Full-text · Article · Jan 2012
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    ABSTRACT: 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 compounds were determined on the basis of 1D and 2D NMR and MS analyses. Among these isolates, nostocionone and reduced scytonemin demonstrated strong antioxidative activities which were assessed by using a β-carotene oxidation assay.
    Full-text · Article · Nov 2011 · Bioscience Biotechnology and Biochemistry
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    ABSTRACT: Low activity (about 4 mU/mg protein) of 5'-deoxyadenosylcobalamin-dependent methylmalonyl-CoA mutase (MCM; EC 5.4.99.2) was found in a cell homogenate of a photosynthetic coccolithophorid alga, Pleurochrysis carterae. Most of the enzyme occurred as the apo-enzyme, which was labile during purification. The holo-enzyme, which was converted from the apo-enzyme by incubation with 10 microM 5'-deoxyadenosylcobalamin at 4 degrees C in the dark, was purified to homogeneity and partially characterized. An apparent molecular mass for the enzyme of 150+/-5 kDa was calculated by Superdex 200 pg gel filtration. SDS-polyacrylamide gel electrophoresis of the purified enzyme gave a single protein band with an apparent molecular mass of 80+/-5 kDa, indicating that the P. carterae enzyme occurs as a homodimer. Some properties of methylmalonyl-CoA mutase from P. carterae were studied.
    Full-text · Article · Jul 2004 · Comparative Biochemistry and Physiology Part B Biochemistry and Molecular Biology
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    ABSTRACT: The inhibitory effects of seven microalgae, Nostoc flagelliforme, Spirulina platensis, Porphyridium purpureum, Rhodosorus marinus,Chlorella pyrenoidosa, Dunaliella salina and Pleurochrysiscarterae on the activation of hyaluronidase were evaluated. Theinhibitory effect of the ethanol-insoluble fraction of each water extract frommicroalgae was stronger than that of the ethanol-soluble fraction. The50% inhibitory concentration (IC50) of the ethanol-insolublefraction of S. platensis, P. purpureum, R. marinus, C.pyrenoidosa, D. salina and P. carterae was 0.15, 0.18, 0.26,0.94, 0.15 and 0.41 mg mL-1, respectively. The IC50 ofN .flagelliforme was not calculated, because there was no detectableinhibitory effect of this alga. The IC50 of disodium cromoglycate(DSCG) used as the anti-allergic medicine was 0.14 mg mL-1. The IC50 of S. platensis, P. purpureum and D. salinawere almost the same as that of DSCG. This suggests that theethanol-insoluble fraction of S. platensis, P. purpureum and D. salina might be an anti-allergic substance. The ethanol-insoluble fractionof S. platensis and D. salina was ultrafiltered through a membranehaving a molecular exclusion limit of 20 kDa. The IC50 of theresidue was stronger than that of the filtrate. These results suggest that theanti-allergic substance(s) of these microalgae may be polysaccharides.
    Full-text · Article · Nov 2001 · Journal of Applied Phycology
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    ABSTRACT: A unicellular coccolithophorid alga, Pleurochrysis carterae, contained 125.4 +/- 1.2 mug of vitamin B-12 per 100 g dry cell weight of the lyophilized algal cells. A vitamin B-12 compound was purified from the lyophilized algal cells and partially characterized. The silica gel 60 TLC and reversed-phase HPLC patterns of the purified pink-colored compound were identical to those of authentic vitamin B-12, but not those of vitamin B-12 analogues inactive for humans. When 22-week-old B-12-deficient rats which excreted substantial amounts of methylmalonic acid (75.5 +/- 12.3 mg/day) in urine were fed the P. carterae (10 g per kg diet)-supplemented diet for 12 d, urinary methylmalonic acid excretion (as an index of vitamin B-12 deficiency) of the rats became undetectable and hepatic vitamin B-12 level of the rats was significantly increased.
    No preview · Article · Jul 2001 · Journal of Agricultural and Food Chemistry
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    ABSTRACT: The safety of the alga Pleurochrysis carterae for food use was evaluated in a 28-day oral subacute toxicity study with rats. The freeze-dried powder of P. carterae was orally administered to male and female rats in dosages of 500 mg/kg and 1000 mg/kg for a period of 28 days. Neither mortality nor changes in the general condition was seen in any of the animal groups, including the control group, throughout the administration period. No reduction of feed consumption or gain in body weight was observed in the experimental animals. Ophthalmological tests performed at the end of the administration period revealed no abnormalities in the ophthalmological parameters. In the hematological tests and serum biochemical tests performed at the time of completion of the administration period, no influences of P. carterae were observed. At autopsy, organ weight measurement at the end of the experimental period and histopathological tests of specimens obtained from the autopsied animals revealed no significant influences of P. carterae feeding. In conclusion, considering the absence of adverse effects of P. carterae in this study, this 28-day oral subacute toxicity study may indicate the safety of P. carterae for human consumption.
    Full-text · Article · Jan 1996 · Journal of Marine Biotechnology
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    ABSTRACT: The mutagenicity of the algaPleurochrysis carterae for use as human food was tested by the Ames method with the modification of pre-incubation, by usingSalmonella typhimurium TA98, TA100, TA1535, TA1537 andEscherichia coli WP2uvrA. The freeze-dried powder ofP. carterae was not mutagenic to any strain either with or without S9 mix. In view of the absence of adverse effects ofP. carterae in this mutagenicity study, it is suggested thatP. carterae is safe for human consumption as a human food supplement.
    No preview · Article · Dec 1995 · Journal of Applied Phycology