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Showing papers in "Bioscience, Biotechnology, and Biochemistry in 1997"


Journal ArticleDOI
TL;DR: In this paper, the effects of methanol extracts of 51 spices on scavenging were studied in detail, and the scavenger of Brassica nigra (brown mustard) was identified as a 3,5-dimethoxy-4-hydroxycinnamic acid methyl ester.
Abstract: The effects of methanol extracts of 51 spices on ·OH scavenging were studied in detail. 2-Deoxyribose oxidation and sodium benzoic acid hydroxylation methods were used for detecting the scavenging activity of ·OH. Mustard varieties, thyme, oregano, clove, and allspice all exhibited strong ·OH-scavenging activity. In particular, 3 varieties of mustard had above 90% ·OH-scavenging activity with a 1 μg/ml concentration of their extracts. The ·OH scavenger of Brassica nigra (brown mustard) was isolated and purified by XAD-2 column chromatography and preparative HPLC, and was identified as a 3,5-dimethoxy-4-hydroxycinnamic acid methyl ester by MS, ‘H-NMR, and 13C-NMR. The 3,5-dimethoxy-4-hydroxycinnamic acid methyl ester was prepared by methylating of sinapic acid with diazomethane.

442 citations


Journal ArticleDOI
Seiya Chiba1
TL;DR: The catalytic reaction mechanisms of carbohydrate-hydrolases were discussed in the two significant models of a nucleophilic displacement mechanism and an oxocarbenium ion intermediate mechanism and α-Glucosidases were suggested to be grouped into two families by their primary structures.
Abstract: The hydrolysis of glucosidic linkage catalyzed by every carbohydrate-hydrolase is a reaction in which the product retains (α→α or β→β) or inverts (α→β or β→α) the anomeric configuration of the substrate. α-Glucosidase and glucoamylase are essentially distinguished by releasing α-glucose and β-glucose, respectively, from the common substrates having α-glucosidic linkage. The distinction in the substrate specificities of the two enzymes was explained by the subsite affinities in their active sites. The amino acid sequences of the regions containing the catalytic sites were compared in α-glucosidases and glucoamylases from various sources. α-Glucosidases were suggested to be grouped into two families by their primary structures. The catalytic reaction mechanisms of carbohydrate-hydrolases were discussed in the two significant models of a nucleophilic displacement mechanism and an oxocarbenium ion intermediate mechanism.

339 citations


Journal ArticleDOI
TL;DR: It is suggested that drinking green tea daily would contribute to maintain plasma catechin levels sufficient to exert antioxidant activity against oxidative modification of lipoproteins in blood circulation systems.
Abstract: Tea catechins, (-)-epigallocatechin-3-gallate (EGCg) and (-)-epigallocatechin (EGC), have been reported to suppress oxidation of plasma low density lipoprotein (LDL) in vitro. If dietary catechins can be efficiently incorporated into human blood plasma, anti-atherosclerotic effects in preventing oxidative modification of LDL would be expected. In this study, a newly developed chemiluminescence detection-high pressure liquid chromatography (CL-HPLC) method for measuring plasma catechins was used and the incorporation of EGCg and EGC into human plasma was investigated. Healthy subjects orally ingested 3, 5, or 7 capsules of green tea extract (corresponding to 225, 375, and 525 mg EGCg and 7.5, 12.5, and 17.5 mg EGC, respectively). The plasma EGCg and EGC concentrations before the administration were all below the detection limit (< 2 pmol/ml), but 90 min after, significantly and dose-dependently increased to 657, 4300, and 4410 pmol EGCg/ml, and 35, 144, and 255 pmol EGC/ml, in the subjects who received 3, 5, and 7 capsules, respectively. Both EGCg and EGC levels detected in plasma corresponded to 0.2-2.0% of the ingested amount. Catechin intake had no effect on the basal level of endogenous antioxidants (alpha-tocopherol, beta-carotene, and lycopene) or of lipids in plasma. These results suggested that drinking green tea daily would contribute to maintain plasma catechin levels sufficient to exert antioxidant activity against oxidative modification of lipoproteins in blood circulation systems.

286 citations


Journal ArticleDOI
TL;DR: The data obtained here indicated that the members of the subgenus Gluconoacetobacter of the genus Acetobacter can be distinguished at the generic level.
Abstract: Thirty-six strains of acetic acid bacteria classified in the genera Acetobacter, Gluconobacter, and Acidomonas were examined for their partial base sequences in positions 1220 through 1375, 156 bases, of 16S rRNA. The strains of the Q10-equipped Gluconobacter species examined were divided into two subgroups, which included the type strains of Gluconobacter oxydans, the type species of the genus Gluconobacter, and of a second species, Gluconobacter cerinus, respectively. The base differences numbered four between the two type strains. The strains of the Q9-equipped species examined classified in the type subgenus Acetobacter of the genus Acetobacter were not very distant phylogenetically from those of the genus Gluconobacter. The calculated number of base differences was 9–6 between the type strains of G. oxydans and G. cerinus and the type strains of Acetobacter aceti and Acetobacter pasteurianus. In contrast, the strains of the Q10-equipped species examined classified in the subgenus Gluconoacetobacter o...

269 citations


Journal ArticleDOI
TL;DR: Recent progress in research on bacterial cellulose is reviewed, which has unique structural and mechanical properties compared with higher plant cellulose and is expected to be a commodity material in various fields of industry.
Abstract: Some Acetobacter strains produce a cellulose called bacterial cellulose in culture medium. This cellulose has unique structural and mechanical properties compared with higher plant cellulose, and is expected to be a commodity material in various fields of industry. For economical mass production, it is essential to construct an aeration and agitation culture process. To explore the industrial applications of the bacterial cellulose, the structural features and physicochemical properties need to be understood and potentially improved. This paper reviews recent progress in research on this bacterial cellulose.

211 citations


Journal ArticleDOI
TL;DR: alpha-Glucosidase inhibitory activity was found in aqueous methanol extracts of tochu-cha, dried leaves of Eucommia ulmoides (Eucommiaceae) and quercetin was considered to contribute mostly to the activity of the tochu leaves.
Abstract: alpha-Glucosidase inhibitory activity was found in aqueous methanol extracts of tochu-cha, dried leaves of Eucommia ulmoides (Eucommiaceae). Five active principles against yeast enzyme were isolated and characterized. Among them, quercetin (1, Ki: 8.5 x 10(-6) M) was considered to contribute mostly to the activity of the tochu leaves. In regard to an animal alpha-glucosidase, rat intestinal sucrase activity was also inhibited by 1.

201 citations


Journal ArticleDOI
TL;DR: Hemperidin was identified as a simple and small molecular weight inhibitor in the peels of Citrus unshiu and inhibited lipase activity from porcine pancreas and that from Pseudomonas.
Abstract: In the course of our screening work for new types of lipase inhibitors, hesperidin was identified as a simple and small molecular weight inhibitor in the peels of Citrus unshiu. Hesperidin inhibited lipase activity from porcine pancreas and that from Pseudomonas, and their IC50 was 32 and 132 micrograms/ml, respectively. Hesperidin, neohesperidin, narirutin, and naringin are known as the main flavonoids in Citrus unshiu. Neohesperidin also inhibited the lipase from procine pancreas, but did not have any effect on Pseudomonas. Narirutin and naringin did not show this effect on lipases from porcine pancreas and Pseudomonas. In animal experiments, the concentration of plasma triglyceride in rats fed a diet containing 10% hesperidin were significantly lower than that fed the control diet.

195 citations


Journal ArticleDOI
TL;DR: The measurement of a point of subjective equality (PSE) showed that the peptide increases the flavor characteristics but did not affect the intensity of basic tastes, which suggests that GSH interacts with the umami substance and has a certain effect on the flavor.
Abstract: The flavor of glutathione (gamma-L-glutamyl-L-cysteinylglycine, GSH) was examined by several sensory evaluations. The measurement of a point of subjective equality (PSE) showed that the peptide increases the flavor characteristics but did not affect the intensity of basic tastes, such as sweetness, saltiness, sourness, and umami. However, the threshold value of GSH decreased significantly in an umami solution containing 0.05% each of monosodium glutamate (MSG) and disodium inosinate (IMP). This suggests that GSH interacts with the umami substance and has a certain effect on the flavor. GSH had a characteristic kokumi flavor, such as continuity, mouthfulness, and thickness in the umami solution as well as in a model beef extract constructed from analyzed components at a concentration of 0.02% w/v. Some foodstuffs, including meat, were found to contain GSH above its threshold value, which implicates the contribution of GSH to the flavor. The thermal degradation study suggested that a part of GSH have changed into its disulfide, pyroglutamic acid (PCA), and cyclocysteinylglycine in cooked foodstuffs.

176 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of temperature, time, pH, and concentration on the conversion of tea catechins to their epimers were examined, and it was determined that the epimerization reaction should be conducted with 1% each of the tea catechin solution (pH5) at l20°C for 30 min.
Abstract: Products from tea catechins ((+)-catechin, (−)-epicatechin, (−)-epigallocatechin, (−)-epicatechin gallate, and (−)-epigallocatechin gallate) after heat treatment were individually isolated by preparative HPLC and subsequent crystallization. FAB-MS, elemental, 1H- and 13C-NMR, and optical rotation analyses indicated these products to be the C-2 epimers of the original catechins. The effects of temperature, time, pH, and concentration on this conversion of tea catechins to their epimers were examined. It was determined that the epimerization reaction should be conducted with 1% each of the tea catechin solution (pH5) at l20°C for 30 min.

169 citations


Journal ArticleDOI
TL;DR: The results suggest that the generation of reactive oxygen species is a common feature of raphidophycean flagellates, and Chattonella has the highest rates of production of O2- and H2O2 as compared on the basis of cell number.
Abstract: Chattonella marina, a raphidophycean flagellate, is one of the most toxic red tide phytoplankton and causes severe damage to fish farming. Recent studies demonstrated that Chattonella sp. generates superoxide (), hydrogen peroxide (H2 O2), and hydroxyl radicals (·OH), which may be responsible for the toxicity of C. marina. In this study, we found that other raphidophycean flagellates such as Hetevosigma akashiwo, Otisthodiscus luteus, and Fihrocapsa japonica also produce and H2O2 under normal growth condition. Among the flagellate species tested, Chattonella has the highest rates of production of and H2O2 as compared on the basis of cell number. This seems to be partly due to differences in their cell sizes, since Chattonella is larger than other flagellate species. The generation of by these flagellate species was also confirmed by a chemiluminescence assay by using 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo[l,2-a]pyrazin-3-one (MCLA). All these raphidophycean flagellates inhibited the proliferation...

161 citations


Journal ArticleDOI
TL;DR: The antioxidant and free radical scavenging effects of dopamine, noradrenaline, tyramine, and tyrosine were investigated and compared with alpha-tocopherol and the results for reducing power and scavenging effect had a similar trend as their inhibition of linoleic acid peroxidation.
Abstract: The antioxidant and free radical scavenging effects of dopamine, noradrenaline, tyramine, and tyrosine were investigated and compared with alpha-tocopherol. The antioxidant effect of dopamine and its related compounds on peroxidation of linoleic acid were in the order of dopamine > alpha-tocopherol = tyramine > tyrosine > noradrenaline as measured by the thiocyanate method. These amine compounds had reducing power, and a scavenging effect on reactive oxygen species, i.e., superoxide anion and hydroxyl radical. The results for reducing power and scavenging effect of these amine compounds had a similar trend as their inhibition of linoleic acid peroxidation. The antioxidant activity of these amine compounds in soybean oil was also evaluated by the Rancimat method. The induction time to reach 100 meq/kg peroxide value (POV) of soybean oil for dopamine, alpha-tocopherol, tyramine, tyrosine, noradrenaline, and control were 9.0, 8.2, 8.0, 6.4, 4.6, and 4.3 h, respectively. The antioxidant efficacy of amine compounds seems to be correlated with the numbers of hydroxy groups and their position on the phenolic ring.

Journal ArticleDOI
TL;DR: Neoagarobiose, a disaccharide, showed a higher hygroscopic ability than glycerol or hyaluronic acid, typical moisturizing reagents, and showed low cytotoxicity.
Abstract: Neoagarobiose, a disaccharide, showed a higher hygroscopic ability than glycerol or hyaluronic acid, typical moisturizing reagents. Beside, neoagarobiose whitened B16 murine melanoma cells, and showed low cytotoxicity. Therefore neoagarobiose was a rare reagent showing both moisturizing and whitening effects.

Journal ArticleDOI
TL;DR: Amino acid analogues are of considerable interest as inhibitors of enzymes involved in amino acid and peptide metabolism, and constitute a unique class of amino acid mimics from which a number of potent enzyme inhibitors have been prepared.
Abstract: Amino acid analogues are of considerable interest as inhibitors of enzymes involved in amino acid and peptide metabolism. In particular, α-aminoalkylphosphonic acids and α-aminoalkylboronic acids, in which the carboxyl group of amino acids is replaced by a phosphonic acid or boronic acid function, respectively, constitute a unique class of amino acid mimics from which a number of potent enzyme inhibitors have been prepared. The inhibitory activity mainly stems from the fact that the tetrahedral phosphonic moiety or the tetrahedral adduct of electrophilic boronic acid is a good mimic of the putative tetrahedral transition state or intermediate encountered in the enzymatic hydrolysis or formation of peptides. Since the peptide hydrolysis and formation invariably involves the tetrahedral high energy species in the course of the reaction, these amino acid mimics serve as a general key element for inhibitors of a broad spectrum of proteases and peptide ligases. The transition state analogy of aminophosphonic- ...

Journal ArticleDOI
TL;DR: In this paper, a cell-free extract of Lactobadllus brevis TFO 12005 was obtained from 90.2 g of wet cells and showed a single protein band on SDS-PAGE.
Abstract: Glutamate decarboxylase (GAD) [EC 4.1.1.15] was purified from a cell-free extract of Lactobadllus brevis TFO 12005 by chromatographies on Sephadex G-100, DEAE-Sepharose CL-6B, and Mono Q. About 9 mg of purified GAD was obtained from 90.2 g of wet cells. The purified preparation showed a single protein band on SDS-PAGE. The molecular weights of purified GAD by SDS-PAGE and gel filtration on Superdex 200 were 60,000 and 120,000, respectively, indicating that GAD from L. brevis exists as a dimer. The N-terminal amino acid sequence of the purified GAD was NH2-Met-Asn-Lys-Asn-Asp-Gln-Glu-Gln-Thr-. The optimum pH and temperature of GAD were at pH 4.2 and at 30°C. The GAD activity was increased by the addition of sulfate ions in a dose-dependent manner. The order of effect was as follows: ammonium sulfate > sodium sulfate > magnesium sulfate, indicating that the increase of hydrophobic interaction between subunits causes the increase of GAD activity. The purified GAD reacted only with l-glutamic acid as a substr...

Journal ArticleDOI
TL;DR: An extracellular glucose-tolerant β-glucosidase was purified to homogeneity by alcohol fractionation and preparative isoelectric focusing from Aspergillus niger CCRC 31494 as discussed by the authors.
Abstract: An extracellular glucose-tolerant β-glucosidase was purified to homogeneity by alcohol fractionation and preparative isoelectric focusing from Aspergillus niger CCRC 31494. The enzyme was a dimeric protein with a subunit of 49,000, and had its optimum activity at pH 5.0 and 55°C. The enzyme was completely inhibited by 5 mm Ag+. Thiol groups and serine residues were not essential for its activity. Low concentrations of alcohols (10%) except for methanol could activate the enzyme. It was very specific for para-nitrophenyl-β-d-glucoside (pNPG) and cellobiose. However, the enzyme also had some β-xylosidase activity, but showed no activity towards α-linked glycosidic substrates. The Vmax of 124.4 U/mg and 21.6 U/mg were found for pNPG (Km = 21.7mm) and para-nitrophenyl-β-d-xyloside (pNPX) (Km = 14.2 mm), respectively. The enzyme was tolerant to glucose inhibition with a Ki of 543 mm, while fructose, galactose, mannose, and xylose were not inhibitory.

Journal ArticleDOI
TL;DR: The biological activities of 7 microbial extracellular glycolipids except for RL were found to induce cell differentiation instead of cell proliferation in the human promyelocytic leukemia cell line HL60, and the results showed that MEL-A, M EL-B, and PL induced HL60 to differentiate into granulocytes, while SL, STL-1, and STL-3 induced differentiation into monocytes.
Abstract: The biological activities of 7 microbial extracellular glycolipids including mannosylerythritol lipid (MEL)-A, MEL-B, polyol lipid (PL), rhamnolipid (RL), sophorose lipid (SL), succinoyl trehalose lipid (STL)-1, and STL-3 were investigated. All glycolipids except for RL were found to induce cell differentiation instead of cell proliferation in the human promyelocytic leukemia cell line HL60. To identify the differentiation direction of the induced cells, the leukocyte esterase activities were cytologically investigated, and the results showed that MEL-A, MEL-B, and PL induced HL60 to differentiate into granulocytes, while SL, STL-1, and STL-3 induced differentiation into monocytes. The 6 effective glycolipids also increased nitroblue tetrazolium (NBT) reducing ability, which is a common differentiation-associated characteristic in monocytes and granulocytes. Furthermore, it was also observed that these 6 glycolipids inhibited the activity of phospholipid- and Ca(2+)-dependent protein kinase. Additionally, the 6 effective glycolipids also induced the human myelogenous leukemia cell line K562 and the human basophilic leukemia cell line KU812 to differentiate into monocytes, granulocytes, and megakaryocytes.

Journal ArticleDOI
TL;DR: It is suggested that ALA have a variety of plant physiological effects on chlorophyll synthesis, photosynthesis, and plant growth, and ALA acts as a growth regulator in plants at low concentrations.
Abstract: 5-Aminolevulinic acid (ALA) promoted the growth and yield of several crops and vegetables at concentrations lower than those eliciting herbicidal responses, i.e., less than 1.8 mm by foliar spray and 60 μm by root soaking. To evaluate the physiological action of ALA, the effects of ALA on plants were examined by several bioassay systems at 0.0006-600 μm. ALA at 0.06-6 μm by root soaking increased the growth of rice seedlings in light, but did not affect this in darkness. In horseradish shoot primordia, promotion by ALA was not proportional among total chlorophyll content, chlorophyll concentration, and fresh weight. In the test using pothos, ALA at 0.06 μm elicited the accumulation of chlorophyll, but the photosynthesis of the plants was promoted by treatment together with ALA and nutrients. These results suggest that ALA have a variety of plant physiological effects on chlorophyll synthesis, photosynthesis, and plant growth, and ALA acts as a growth regulator in plants at low concentrations. These effects of ALA were also assumed to be linked to light irradiation and an uptake of fertilizer by plants. However, excess ALA suppressed these effects.

Journal ArticleDOI
TL;DR: The bacterial cellulose produced in an agitated culture (Ag-BC) showed the highest emulsion-stabilizing effect among the examined cellulosk materials as mentioned in this paper, which was due to the stability of the mechanical barrier and a scaffolding structure composed of stable crystalline cellulose.
Abstract: The bacterial cellulose produced in an agitated culture (Ag-BC) showed the highest emulsion-stabilizing effect among the examined cellulosk materials. It was clarified that a mechanical barrier and a scaffolding structure composed of fine fibrils of bacterial cellulose interrupted the coalescence of oil droplets to stabilize the emulsion without reducing the interfacial tension as occurred with sorbitan monolaurate. Since Ag-BC consists of thinner fibrils and smaller floes than any other cellulosic material, Ag-BC would cover a larger surface area of the oil droplet as a mechanical barrier.The emulsion containing Ag-BC was stable against the addition of salt, and changes in pH and temperature in comparison with xanthan gum and sorbitan monolaurate. This stability would have been due to the stability of the mechanical barrier and a scaffolding structure composed of stable crystalline cellulose. In contrast, instability in the conformation of xanthan gum and a reduction in the interfacial tension of the sur...

Journal ArticleDOI
TL;DR: The results suggest that DPE is a potent specific inhibitor of lipoxygenase activities, especially in intact cells.
Abstract: The effects of olive fruit extract on arachidonic acid lipoxygenase activities were investigated using rat platelets and rat polymorphonuclear leukocytes (PMNL). Olive extract strongly inhibited both 12-lipoxygenase (12-LO) and 5-lipoxygenase (5-LO) activities. One of the compounds responsible for this inhibition was purified and identified as 2-(3,4-dihydroxyphenyl)ethanol (DPE). DPE inhibited platelet 12-LO activity (IC50, 4.2 μμ) and PMNL 5-LO activity (IC50, 13 μμ) but not cyclooxygenase activity in cell-free conditions. It also inhibited 12-LO activity in intact platelets (IC50, 50 μμ) and reduced leukotriene B4 production in intact PMNL stimulated by A23187 (IC50, 26μμ). The inhibition by DPE of both lipoxygenase activities was stronger than that by oleuropein, caffeic acid, or 7 other related phenolic compounds, especially in intact cells. These results suggest that DPE is a potent specific inhibitor of lipoxygenase activities.

Journal ArticleDOI
TL;DR: The soluble and insoluble fractions obtained after sonication and centrifugation of Bifidobacterium adolescentis M101-4 cells were examined, and both of these fractions exhibited mitogenic activity in an assay of murine splenocytes and Peyer's patch cells in vitro.
Abstract: The soluble and insoluble fractions obtained after sonication and centrifugation of Bifidobacterium adolescentis M101–4 cells were examined, and both of these fractions exhibited mitogenic activity in art assay of murine splenocytes and Peyer’s patch cells in vitro. The soluble fraction was further treated by a 6-step procedure involving proteinase K-treatment, ultrafiltration with a 50-kDa cut-off molecular-sieving membrane, anion-exchange chromatography, dialysis, ultrafiltration through a 6-kDa cut-off membrane filter, and gel-filtration to yield a soluble high molecular weight fraction (SHF) which was effective for stimulating the proliferation of murine splenocytes. Almost three quarters of this fraction by weight was found to consist of carbohydrates containing glucose and galactose as major constituents, and the average molecular weight was estimated to be between 60,000 and 2,460,000, with the main peak at 1,550,000 Da, by the retention time of gel permeation chromatography. A structural analysis ...

Journal ArticleDOI
TL;DR: The method confirmed the occurrence of YTX and 45-OHYTX for the first time in mussels from Chile and New Zealand.
Abstract: A rapid HPLC method with fluorescence detection of yessotoxin (YTX) and its two analogs (45-OHYTX and norYTX) in mussels and scallops is presented. A dienophile reagent, DMEQ-TAD, was used for fluorescence labeling. YTX was measured in the range 1-100 ng. The method confirmed the occurrence of YTX and 45-OHYTX for the first time in mussels from Chile and New Zealand.

Journal ArticleDOI
TL;DR: Among the fermented foods, soy sauces were rich in putrescine and histamine, while Japanese sake contained plenty of agmatine, which are thought to be produced from amino acids during fermentation with amino acid decarboxylases formed by the micro-organisms.
Abstract: Soybeans, tea leaves, and mushrooms were conspicuously rich in spermidine, while oranges contained a large amount of putrescine. Among the fermented foods, soy sauces were rich in putrescine and histamine, while Japanese sake contained plenty of agmatine. These polyamines are thought to be produced from amino acids during fermentation with amino acid decarboxylases formed by the microorganisms.

Journal ArticleDOI
TL;DR: A transformation system for Aspergillus oryzae using the As pergillus nidulans sC gene encoding ATP sulfurylase as a selectable marker was developed, indicating that with this transformation system, the transformation marker could be selected according to the integration pattern one desires.
Abstract: We developed a transformation system for Aspergillus oryzae using the Aspergillus nidulans sC gene encoding ATP sulfurylase as a selectable marker. The sC− mutants can be readily isolated by positive selection for selenate resistance, thereby the niaD− mutant strain of A. oryzae was bestowed with the sC− mutation. Transformation of the A. oryzae host (niaD−,sC−) with the plasmid carrying A. nidulans sC gave random and multi-copy integrants, while that with the A. oryzae niaD-carrying plasmid occurred mainly by single-copy and homologous integration events (more than 50% frequency), indicating that with this transformation system, the transformation marker could be selected according to the integration pattern one desires.

Journal ArticleDOI
TL;DR: This review covers recent examples of synthetic transformation of nitriles and amides by microbial enzyme systems, with special emphasis upon the range of functional groups that are acceptable by enzymes and/or survive under the transformation, as well as the advantages as a synthetic tool for conversion under mild conditions.
Abstract: This review covers recent examples of synthetic transformation of nitriles and amides by microbial enzyme systems. A variety of substrates and products involving enantiomerically enriched forms of chiral substances are referred to. The stereochemical course of enzyme-catalyzed hydrolysis is briefly commented on. Special emphasis is placed upon the range of functional groups that are acceptable by enzymes and/or survive under the transformation, as well as the advantages as a synthetic tool for conversion under mild conditions.

Journal ArticleDOI
TL;DR: H hop extract was searched for active component(s) that inhibited bone resorption in the pit formation assay, and xanthohumol and humulone were isolated as active ingredients.
Abstract: We searched hop extract for active component(s) that inhibited bone resorption in the pit formation assay, and isolated xanthohumol and humulone as active ingredients. Especially humulone had extraordinarily strong inhibitory activity and the IC50 (concentration of 50% inhibition) value was 5.9 x 10(-9)M.

Journal ArticleDOI
TL;DR: Though the complete taxonomic analysis has not been completed with all the strains, the majority of the acetic acid bacteria isolated have been confirmed to be classified as Acetobacter rancens subsp.
Abstract: Thermotolerant acetic acid bacteria that can grow at 37 to 40°C were collected from places all over Thailand. They were divided into several groups according to their taxonomic and physiological properties, such as rapid ethanol oxidation, rapid acetate oxidation, cellulosic biopolymer formation, growth at 40°C, growth in 3% acetic acid, growth in 8% ethanol, formation of thermotolerant alcohol, and aldehyde dehydrogenases, etc. Though the complete taxonomic analysis has not been completed with all the strains, the majority of the acetic acid bacteria isolated have been confirmed to be classified as Acetobacter rancens subsp. pasteurianus, A. lovaniensis subsp. lovaniensis, A. aceti subsp. liquefaciens, and A. xylinum subsp. xylinum. They produced acetic acid at high temperatures such as 38 to 40°C. Even when acetic acid was initially added to 4%, they still oxidized ethanol to accumulate acetic acid, while 2% of the initial acetic acid was the upper limit for mesophilic strains*1 at higher temperatures. ...

Journal ArticleDOI
TL;DR: The presence of resveratrol and its beta-glucoside, piceid, together with their isomers in wine appears to be one of the beneficial factors conferring a protective effect against cardiovascular disease through red wine ingestion.
Abstract: The presence of resveratrol (3,5,4'-trihydroxystilbene) and its beta-glucoside, piceid (resveratrol-3-beta-D-glucopyranoside), together with their isomers in wine appears to be one of the beneficial factors conferring a protective effect against cardiovascular disease through red wine ingestion. A total of 42 red and white wines was collected in areas from Hokkaido to Kyushu in Japan. The wines were fractionated with a C18 Sep-pak cartridge, and the active principles were eluted with ethyl acetate. Crude trans- and cis-piceid were extracted from a Chinese medicine, 'Kojohkon' (Polygonum cuspidatum), and their retention times and UV absorption were confirmed by HPLC. trans- and cis-Resveratrol, and trans- and cis-piceid were analyzed in a short C18 HPLC column, and cis-resveratrol was quantified from the amount of cis-isomer converted from authentic trans-resveratrol that had been treated by UV irradiation. The content of piceid is shown as the resveratrol equivalent. The average content of total stilbene compounds was 4.37 mg/liter in red wines, while only 0.68 mg/liter in white wines. Red wines made from Pinot noir, Merlot, and Zweigeltrebe grapes all had a high resveratrol content.

Journal ArticleDOI
TL;DR: The water activity and the activity coefficient of water (γw) were calculated from the freezing point depression by using the Hildebrand and Scott's equation for various solutions of electrolytes, sugars, alcohols, amide, and urea.
Abstract: The water activity and the activity coefficient of water (γw) were calculated from the freezing point depression by using the Hildebrand and Scott’s equation for various solutions of electrolytes, sugars, alcohols, amide, and urea. The water activity measured from the freezing point depression was very close to that at room temperature, showing that the effect of temperature on the water activity is neglegible. The activity coefficient of water was described well as a function of the solute mole fraction (Xs) by the following equation. The parameter α in this equation correlated well with the B-coefficient of viscosity for single-valent electrolytes, with the hydration parameter for nonelectrolytes, and with the number of equatorial-OH groups for sugars suggesting that the solution structure was reflected in this parameter.

Journal ArticleDOI
TL;DR: The relationship between glutamate production and the enzyme activities as well as permeability of glutamate through cell membrane was discussed and significant reduction of the former enzyme activity was observed in cells under the several glutamate-productive conditions.
Abstract: Enzyme activities of 2-oxoglutarate dehydrogenase complex and glutamate dehydrogenase of wild type Brevibacterium lactofermentum, one of the typical glutamate-producing coryneform bacteria, were investigated by using cells cultured under glutamate-productive and glutamate-non-productive conditions. Significant reduction of the former enzyme activity was observed in the cells under the several glutamate-productive conditions, namely, in the cells cultured in media containing a) limited concentrations of biotin, b) sub-lethal amounts of penicillin, and c) sub-optimal amounts of a surface-active agent, as compared with those under the non-productive conditions. The activity of the latter enzyme was essentially unchanged in every condition. The relationship between glutamate production and the enzyme activities as well as permeability of glutamate through cell membrane was discussed from the results obtained.

Journal ArticleDOI
TL;DR: When a series of chitin oligosaccharides was added into a rice suspension culture, N-acetylchitohexaose, N+1,3-Glucanase activity was found in cells (but not in medium), and the activity was increased by neither N- acetylchitotriose nor laminarihexaoses, while L-phenylalanine ammonia-lyase activity increased promptly.
Abstract: When a series of chitin oligosaccharides was added into a rice suspension culture, N-acetylchitohexaose, N-acetylchitopentaose, and N-acetylchitotetraose caused an increase in extracellular chitinase activity, mainly due to induction of a class III chitinase. In the case of N-acetylchitohexaose, a substantial increase in the chitinase activity was observed at a concentration higher than 0.01 micrograms/ml, and a maximum effect was reached at 1 microgram/ml. In contrast, N-acetylchitotriose, N-acetylchitobiose, N-acetyl-D-glucosamine, and chitohexaose (a chitosan oligosaccharide) were not very effective. Chitinase induction was also observed with laminarihexaose (a beta-1,3-glucan oligosaccharide), but about a 10-fold higher concentration, compared with N-acetylchitohexaose, was needed to get the maximum effect. beta-1,3-Glucanase activity was found in cells (but not in medium), and the activity was increased by neither N-acetylchitohexaose nor laminarihexaose. When cells were incubated with N-acetylchitohexaose, L-phenylalanine ammonia-lyase (PAL) activity increased promptly. A biphasic profile was obtained when a dose-dependent effect of the elicitor on the PAL induction was examined; the first phase was observed in a range from 0.01 to 1 microgram/ml and the second phase from 3 to 300 micrograms/ml. Laminarihexaose also acted as an elicitor for PAL induction.