31-1
Systematic Review and Verification of Preventive Effects of Soy Constituents on Lifestyle-related Diseases:
Effects of ingesting soy isoflavones on bone turnover markers in menopausal women and blood pressure
in adult humans: systematic review and meta-analysis of randomized controlled trials (Part III)
Yoshiko ISHIMI1 , Kyoko TAKU2 and Jun YAMAUCHI1, 3
1 Food Function and Labeling Program,
2 Project for Health Communication, Information Center,
3 Project for Bio-index, Nutritional Epidemiology Program, National Institute of Health and Nutrition, Tokyo 162-8636
ABSTRACT
Recent growing interest in health and diet has led to an increased assessment of the health Effects of soy foods and their functional components. However, the consensus on their effectiveness has not been achieved so far. In order to propose the appropriate intake of the functional components in the soy foods, this study was aimed to 1) examine the Effects of the functional components of soy foods on prevention of life style-related diseases via systematic review and meta-analysis of the related articles, 2) survey the labeling and the contents of functional components of soy in the health foods. This year, we performed one meta-analysis to clarify the eff ect of soy Isoflavone supplements on bone turnover markers in menopausal women and another to clarify the eff ect of soy Isoflavone extract supplements on blood pressure in adult humans. PubMed, CENTRAL, ICHUSHI, CNKI up to June 2009 were searched for published articles of randomized placebo-controlled trials reporting the outcomes of soy Isoflavone supplements on bone turnover markers (e.g. urinary deoxypyridinoline (DPD), serum bone alkaline phosphatase (BAP), or serum osteocalcin (OC)) in menopausal women and blood pressure (BP) in adult humans. Meta-analysis of 10 trials including 887 menopausal women, revealed that daily in gestion of an average of 56 (14-114) mg soy Isoflavones (aglycone equivalents) for 10 weeks to 12 months significantly decreased DPD by 14.1% (95% CI:―26.8% to ―1.5%; p =0.03) compared to baseline (heterogeneity: p <0.00001; I2 =93%; random effects model). The overall eff ect of soy Isoflavones on DPD compared with placebo was a significant decrease of ―18.0% (95% CI: ―28.4% to ―7.7%, p =0.0007; heterogeneity: p =0.0001; I2 =73%; random Effects model). Daily supplementation of about 84 mg and 73 mg of soy Isoflavones for up to 12 months did not aff ect serum BAP and OC. Daily ingestion of 25-375 mg soy Isoflavones (aglycone equivalents) for 2-24 weeks significantly decreased systolic BP by 1.92 mmHg (95% CI: ―3.45 to ―0.39; p =0.01) compared with placebo (heterogeneity: p =0.39; fi xed eff ect model), in adults with normal blood pressure and prehypertension. Soy isoflavones did not affect diastolic BP.When the labeling and Isoflavone content of 13 commercially available soy foods or dietary supplements with Isoflavone obtained from foreign countries were assessed, soy Isoflavone contents of one serving of soy foods from Thailand and China were almost the same as those in Japanese soy foods, and soy Isoflavone aglycone contents of one serving of the dietary supplements from the USA were ranged from 25 to 52 mg and these were almost the same as those reported on the labels of the foods. Taken together with these findings and the results of the last 2 years, there is the possibility that intake of soy foods fortifi ed with soy protein or Isoflavones in addition to the normal diet prevents lifestyle-related diseases including hyperlipidemia, high blood pressure and osteoporosis in middle aged men and menopausal women.
Soy Protein Research, Japan 13, 1-15, 2010.
Key words : soy foods, health foods, isoflavones, bone turnover markers, blood pressure, menopausal women
31-2
Studies on Ca Bioavailability of Soybean Products
Chie TARUMIZU1 , Vu THI THU Hien1, 2 , Nobuko SARUKURA1 , Noriko WAKIKAWA1 ,
Andrea WAKITA1 and Shigeru YAMAMOTO1
1 Ochanomizu University, International Nutrition, Tokyo 112-8610,
2 National Institute of Nutrition, Vietnam
ABSTRACT
There are contradictions in our knowledge concerning the bioavailability of food Ca. The Ca concentration of TOFU is as high as that of cow's milk, while the bioavailability of the former is believed to be lower than that of the latter. This is based on a report from an old study in Japan; however, studies from all over the world show rather similar Ca absorption rates for TOFU, soybean products, cow's milk and dairy products. The purpose of this study was to find the absorption rates and bioavailability for Ca in soybean products and cow's milk by 3 balance studies over 3 years. In the 3 studies, 12-15 different age female subjects were randomly allocated into 2 groups and given basal diets (Ca 300 mg/d) with soybean products (Ca 300 mg/d) or cow's milk (Ca 300 mg/d) for 15 days separated by about a 15 day washout interval in a cross-over design. Basal diets were 3-5 cycle menus. Feces, urine and diets of the last 5 d were collected in both dietary periods and were analyzed for Ca concentration. The apparent absorption rates were 20-30% both in the soybean products and cow's milk group and statistical differences were not observed. In conclusion, the present 3 studies show that the Ca absorption rates of soybean products and cow's milk were 20-30% and similar in women of different ages.
Soy Protein Research, Japan 13, 16-22, 2010.
Key words : Ca, soybean, milk, absorption rate, balance, women
31-3
Transcriptome and Proteome Analysis of Molecular Mechanism in Overcoming Insulin Resistance by a
Soybean Isoflavone, Genistein
Kazumi YAGASAKI1, 2 , Toshiaki SUEYASU3 , Byung Geun HA2 , Katsuki ITOU1 , Takayuki YONEZAWA2 and Hisanori KATO3
1 Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Tokyo 183-8509
2 Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033
3 Organization for Interdisciplinary Research Project, The University of Tokyo, Tokyo 113-8657
ABSTRACT
We previously reported that the soybean Isoflavone genistein shows anti-diabetic activity in type 2 diabetic model mice. To clarify the modes of action of genistein, the effects of genistein on glucose metabolism and signal transduction were investigated in rat L6 myotubes and muscle tissue of type 2 diabetic db/db mice. DNA microarray analysis showed that 422 genes were up-regulated and 712 genes were down-regulated by treatment with genistein in L6 myotubes cultured under normal glucose medium. The results of pathway analysis suggested that genisitein activates AMPK/PKCλ-GLUT4 pathway by decreasing PARD3 expression and increasing IL-6 expression. Signal inhibitors of AMPK and O-GlcNAcase canceled genistein-induced increase of glucose consumption in L6 myotubes cultured both under both normal and high glucose media. Genistein time-dependently promoted AMPK phosphorylation and GLUT4 translocation to plasma membrane of L6 myotubes. In DNA microarray analysis of muscle tissue from db/db mice, upregulation of 637 genes and down-regulation of 610 genes were induced by the administration of genistein. Genistein is indicated as changing the mRNA expressions of many TNF-αdownstream genes in pathway analysis. In fact, the serum TNF-αprotein level was decreased in genistein-treated db/db mice. These results indicated that various pathways were concerned with the anti-diabetic action of genistein.
Soy Protein Research, Japan 13, 23-29, 2010.
Key words : diabetes, genistein, muscle cells, glucose uptake, microarray
31-4
Physiological Function of Highly purified Soy Proteins
Reiko URADE1 and Mitsutaka KOHNO2
1 Graduate School of Agriculture, Kyoto University Gokasho, Uji 611-0011,
2 Food Science Institute, Fuji Oil Co., LTD. 1 Sumiyoshicho, Izumisano 598-8540
ABSTRACT
HepG2 cells were treated with short peptides (7S-peptides) derived from highly purified soybean β-conglycinin, which was free from lipophilic protein, and the eff ect of the peptide treatment on lipid metabolism was determined. 7S-peptide-treatment suppressed the secretion of apolipoprotein B-100 from HepG2 cells into the medium. The 7S-peptides also suppressed the incorporation of 3H-glycerol and 14C-acetate into triacylglyceride, but not into major phospholipids, such as phosphatidylcholine and phosphatidylethanolamine. Additionally, the synthesis of cholesterol esters was dramatically decreased for 2 h after the addition of the 7S-peptides, whereas the synthesis of cholesterol remained unchanged by 4 h and increased by 8 h after the addition of the 7S-peptides. The cleaved nuclear form of SREBP-2 increased 8 h after the addition of the 7S-peptides, suggesting a decrease in intracellular cholesterol levels. Analysis of changes in mRNA expression after 7S-peptidetreatment suggested that the 7S-peptides increase the mRNA of genes related to β-oxidation of fatty acids and the synthesis of cholesterol. From these results, it may be concluded that the peptides derived from β-conglycinin altered the lipid metabolism to decrease secretion of apolipoprotein B-100-containing lipoprotein from HepG2 cells.
Soy Protein Research, Japan 13, 30-36, 2010.
Key words : β-conglycinin, apolipoprotein B-100, very low density lipoprotein, triacylglycerol, HepG2 cell.
31-5
Gene Manipulation of the Biosynthetic Pathway for Molecular Breeding of Soybean Flavonoids
Tetsuya YAMADA and Keisuke KITAMURA
Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589
ABSTRACT
Flavonoid content and composition in soybean seeds are sensitive to a change in the growth environment. In breeding soybeans, it is important to maintain stable high flavonoid content in soybean seeds, because flavonoids are known to possess various pharmaceutical Effects for human health. Some transcriptional factors that control the expression of the enzymatic genes involved in the biosynthetic pathway of flavonoids have been used to improve the flavonoid components in higher plants by a transgenic technology. We produced transgenic plants over-expressing a Myblike transcriptional factor gene, LjMyb12 , from Lotus japonicus to improve flavonoid composition in soybean. We generated transgenic soybean lines by repeating selffertilization to fi x transgenes in the genome of transgenic plants. Quantitative RTPCR analysis of flavonoid biosynthesis-related genes was conducted in a soybean transgenic line, indicating that expression of 4-Coumarate:CoA ligase, Chalcone isomerase, Flavanone 3-hydroxylase (F3H ), and Flavonol synthase (FLS ) genes were increased in young leaves of the transgenic line. The expression of F3H and FLS genes was also enhanced in developing seeds. LC-MS/MS analysis revealed that glycosides of kaempferol, which is one of the fl avonols, were markedly increased in mature seeds of transgenic soybean. On the other hand, changes of Isoflavone content were not detected. Thus, we demonstrated that over-expression of the LjMyb12 gene could be useful for molecular breeding of soybean flavonoids.
Soy Protein Research, Japan 13, 37-42, 2010.
Key words : transgenic technology, transcriptional factor, flavonoid biosynthesis, soybean, molecular breeding
31-6
Production of Non-Genetically Modifi ed Food-Use Soybeans with High Functional Properties Using
Soybean- and Wild Soybean-Natural Variants with different Composition of Seed Saponin Components
Chigen TSUKAMOTO1 , Nana TATSUZAKI1 , Ippei TAYAMA1 , Hiroko SASAMA1 , Yoshitake TAKADA2 ,
Shin KATO3 , Akio KIKUCHI3 , Masao ISHIMOTO4 and Keisuke KITAMURA5
1 Faculty of Agriculture, Iwate University, Morioka 020-8550,
2 National Agricultural Research Center for Western Region
3 Tohoku Regio and
4 Hokkaido Region
5 Graduate School of Agriculture, Hokkaido University, Sapporo 060-8559
ABSTRACT
Soybean saponins are divided into two groups: Group A saponins which are the primary cause of undesirable tastes, and DDMP saponins which possess health beneficial characteristics. The degree of the taste characteristics and functional properties of saponin components depend on their chemical structures and density in the seeds. Genetic improvement of the saponin composition and density of fooduse soybeans is expected to spread rapidly worldwide; however, the relationship between genetic modification of saponin composition and accompanying changes in saponin contents is not yet clearly understood. Therefore, in this study, some mutants discovered in G . max collections and wild G . soja accessions in Japan which carry different saponin compositions were used to prepare hybrid F1 seeds, progeny F2 and F3 seeds, and recombinant inbred lines (RILs). Saponin compositions and contents having different combinations of genes controlling the sugar chain sequences at the C-3 and C-22 positions of soyasapogenol glycosides were determined by LC/PDA/MS/MS analysis and were evaluated by statistical analysis. Different combinations of the genes (phenotypes) did not change seed saponin contents even though their saponin composition was changed according to the combinations of the genes. These results suggest that the supply of common precursors (soyasapogenols A and B) in saponin biosynthesis is not changed by the combination of these genes, and that saponin precursors (soyasapogenol glycosides) are competitively used as the substrates of some glycosyltransferases according to the recombination of the genes. Production of expected, specific, or sole saponin component in soybean seeds by using soybean- and wild soybean-natural variants would be possible.
Soy Protein Research, Japan 13, 43-50, 2010.
Key words : Glycne max , Glycine soja , saponin polymorphism, sugar chain sequence, Non-GMO soybeans
31-7
Identification of Genes Controlling the Contents of Seed Storage Proteins in Soybean
―Fine Mapping of the Quantitative Trait Locus qPro7 ―
Masayoshi TERAISHI, Yutaka OKUMOTO, Takanori YOSHIKAWA,
Ryota ENDO and Takatoshi TANISAKA
Graduate School of Agriculture, Kyoto University, Kyoto 606-8502
ABSTRACT
Soybean seed storage protein consists of two major components, 7S and 11S globulin, which together account for 70% of the total and have complementary relationships. We reported that QTL analysis, using 96 recombinant inbred lines derived from the cross between Peking and Tamahomare (PT-RILs), detected two QTLs, qPro1 (linkage group I) and qPro7 (linkage group O). These two QTLs proved to determine the content ratio of 7S globulin to 11S globulin (7S/11S ratio). Peking-type alleles of the two QTLs increased 7S globulin content and decreased 11S globulin content. 634 plants derived from a heterozygote PT-RIL line of qPro7 region (Satt445 - Sat_318 ; 513.1 kb) were planted and relationships between their genotype around the qPro7 region and 7S/11S ratio were examined. Peking-type homozygotes have higher 7S/11S ratios than Tamahomare-type homozygotes. Protein content analysis of the progenies, which harbored a recombination within the qPro7 region, narrowed the location of qPro7 in a 401.7 kb-region between Satt445 and s124-110. We suggest that a regulation factor of 7S and 11S globulin might be present in this region.
Soy Protein Research, Japan 13, 51-54, 2010.
Key words : seed storage protein, QTL, recombinant inbred line, fi ne mapping
31-8
Mechanisms of cGMP/NO Signal Transduction Controlling Gene Expression of
Soybean Flavonoid-Biosynthetic Enzymes
Kenji SUITA, Tatsuya OHARA, Shunsuke YANO, Misaki TOYOSHIMA and Hiroshi YAMAGATA2
Graduate School of Agricultural Science, Kobe University, Kobe 657-8501
ABSTRACT
Several genes encoding flavonoid-biosynthetic enzymes in soybean (Glycine max L.) were induced by cyclic guanosine 3', 5'-monophosphate (cGMP) and nitric oxide (NO), indicating that cGMP and NO act as second messengers to activate the expression of these genes. Loss- and gain-of-function experiments showed that the upper region in the promoter of chalcone reductase gene (CHR ) was responsible for the gene induction by cGMP. DNA microarray analysis using the Arabidopsis T87 suspension culture showed that the expression of many genes was enhanced or repressed by cGMP and/or NO. These results indicated that cGMP and NO functionally linked with each other for the regulation of many genes in plants. On the other hand, the different mechanisms for transcriptional regulation between plant species was suggested based on the observation that the expression of most flavonoid biosynthetic genes was not altered by cGMP/NO in Arabidopsis in contrast to soybean. Arabidopsis nicotianamine synthase 1 (AtNAS1), a key enzyme for response to iron deficiency, was activated by cGMP and NO. The upstream region in AtNAS1 responsible for the induction by cGMP was found to be separated from the NO-responsive sequence, suggesting that the cGMP- and NOmediated signaling pathways for the induction of AtNAS1 are likely to be different from each other.
Soy Protein Research, Japan 13, 55-61, 2010.
Key words : flavonoid, gene expression, cGMP, nitric oxide, signal transduction
31-9
Production of Poly-γ-Glutamic Acid, the Material for Biodegradable Plastic, from Okara Using Bacillus Natto
Hideyuki SUZUKI and Miko WATANABE
Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585
ABSTRACT
Okara, soy bean curd refuge, is regarded as an industrial waste. We developed a method to produce useful poly-γ-glutamic acid (PGA) from okara employing Bacillus natto . B. natto was grown on okara-medium plate containing 5 g dried okara, which corresponds to 25 g raw okara, produced 125 mg of PGA after 3 days of incubation at 37℃. This indicates that 60% of the glutamic acid in okara was transformed to PGA.
Soy Protein Research, Japan 13, 62-65, 2010.
Key words : poly-γ-glutamic acid, biodegradable plastic, waste product, biopolymer, bean curd refuse
31-10
Solar Hydrogen Production from Soybean Oligosaccharide Waste Fluid
Yutaka AMAO
Department of Applied Chemistry, Oita University, Oita 870-1192
ABSTRACT
Visible light-induced enzymatic hydrogen production coupling the saccharide degradation with invertase and glucose dehydrogenase (GDH) and hydrogen production with platinum colloid as a catalyst using the visible light-induced photosensitization of Mg chlorophyll-a (Mg Chl-a) has been developed. The continuous hydrogen gas production was observed when the reaction mixture containing saccharide sucrose, invertase, GDH, nicotinamide adenine dinucreotide (NAD+ ), Mg Chl-a , methylviologen (MV2+ , an electron relay reagent) and platinum colloid was irradiated by visible light. Moreover, this system was applied to the photoinduced hydrogen production from saccharide waste fluid containing 10% sucrose. After 4 h irradiation, 0.3μmol of hydrogen was produced with the system containing saccharide waste fl uid containing sucrose, invertase, GDH, NAD+ , Mg Chl-a , MV2+ and platinum colloid.
Soy Protein Research, Japan 13, 66-69, 2010.
Key words : Solar hydrogen, Biomass, Oligosaccharide, Photosynthesis
31-11
Effect of a Hydrolysate Prepared from Soy Protein High Molecular Weight Fraction on GLP-1 Secretion and
Glycemia in Rats
Tohru HIRA, Maya MURAMATSU and Hiroshi HARA
Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589
ABSTRACT
Glucagon-like peptide-1 (GLP-1) is known as an incretin hormone that is released from enteroendocrine L cells and enhances insulin secretion after meal ingestion. Sugar and fatty acids are well known to stimulate GLP-1 secretion. But studies are limited on protein/peptide-induced GLP-1 secretion. Recently, we demonstrated that a hydrolysate (ZeinH) prepared from the indigestible corn protein. Zein stimulates GLP-1 secretion and attenuates hyperglycemia in rats. In the present study, a hydrolysate was prepared from soy protein isolate indigestible fraction (high molecular weight fraction: HMF), and examined whether HMF hydrolysate (HMFH) stimulates GLP-1 secretion and affects glycemia. HMFH induced significant increase in GLP-1 secretion and intracellular calcium mobilization in GLP-1-producing enteroendocrine cell lines. Direct administration of HMFH solution into the ileal ligated loop of anesthetized rats induced significant increase in GLP-1 concentration in the ileal vein. However, HMFH administered into the ileum of conscious rats did not attenuate hyperglycemia induced by intraperitoneal glucose injection. In contrast, ileal ZeinH attenuated hyperglycemina. In our previous study, ZeinH was reported to reduce GLP-1 degradation in the plasma in addition to stimulating GLP-1 secretion. Results in the present study suggest that HFMF is insuffi cient to attenuate hyperglycemia due to the lack of potency to prevent GLP-1 degradation.
Soy Protein Research, Japan 13, 70-74, 2010.
Key words : GLP-1, HMF, undigestible protein
31-12
Study of the Molecular Targets of Lipid Metabolism Improvement Caused by Soy Protein Intake Using Gene Defect Mice
Ryuichiro SATO
Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657
ABSTRACT
Wild type and FXR KO mice were administered with either 20% casein or soy protein isolated (SPI) diet for 10 days. Blood components and gene expression in the liver were analyzed. There were no changes in blood components between two animal groups or diets. SPI reduced the expression of a set of genes related to fatty acid synthesis or gluconeogenesis in wild type mice, whereas no reduction was observed in FXR KO mice with SPI. These results show that SPI intake gives rise to improve carbohydrate and lipid metabolism prior to making a change in blood components. In addition, the expression of FXR target genes in the intestine of wild type mice was found to be suppressed by feeding SPI. This finding well interprets nonresponse to feeding SPI in FXR KO mice.
Soy Protein Research, Japan 13, 75-78, 2010.
Key words : Soy protein, FXR, Bile acid, Fatty acid synthesis, Gluconeogenesis.
31-13
Study of the Regulation of Drug Metabolizing Enzymes by Soybean Ingredients in Intestinal Epithelial Cells
Hideo SATSU, Tomohiko MIZUKAMI, Ayano MIKUBO and Makoto SHIMIZU
Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657
ABSTRACT
The effect of soybean ingredients on the expression level of drug metabolizing enzymes in human intestinal epithelial cells was examined. Among soybean ingredients, the saponin fraction most extensively increased the mRNA levels of CYP1A1, UGT1A1, and MDR1 in human intestinal epithelial LS180 cells. The saponin fraction significantly induced the promoter activity of CYP1A1, UGT1A1, and MDR1, and also pregnane X receptor (PXR)-dependent transcriptional activity. Soyasaponin I, one of the major component of the saponin fraction, also increased the mRNA levels of these enzymes and PXR-dependent transcripotional activity, suggesting that one of the active components in the saponin fraction is soyasaponin I. We further examined the eff ect of Isoflavones on the mRNA levels of CYP1A1, UGT1A1, and MDR1 in LS180 cells. Among seven Isoflavones, equol and genistein increased the mRNA levels of these enzymes. Equol also increased the promoter activity, protein expression, and functional activity of MDR1. Nuclear localization and transcriptional activation of PXR by equol were also observed, suggesting that equol induces MDR1 expression and activity via PXR activation. These results show that the drug metabolizing enzymes in intestinal epithelial cells are induced by various soybean ingredients such as soyasaponin I and equol, suggesting that soybean ingredients could strengthen the biological barrier function of intestinal epithelial cells against invasion by xenobiotics and toxicants.
Soy Protein Research, Japan 13, 79-84, 2010.
Key words : intestinal epithelial cell, drug metabolizing enzyme, equol, MDR1, pregnane X receptor
31-14
Differential Effects of Casein and Soy Protein Isolate on Mucin Secretion
Stimulated by Dietary FiberIngestion in the Rat Small Intestine
Tatsuya MORITA, Hiroyuki ITO, Daisuke SAITO, Akio MORITA and Kimio SUGIYAMA
Faculty of Agriculture, Shizuoka University, Shizuoka 422-8529
ABSTRACT
We compared the effects of soy protein isolate (SPI) with casein on the mucin secretion stimulated by dietary fiber ingestion in the rat small intestine. We used polystyrene foam (PSF) as a high-bulk forming fiber. Rats were fed the diets including casein or SPI at a dietary protein level of 25% with or without concurrent addition of 8% PSF for 10 days. Small intestinal mucin content and number of total goblet cells in the ileum were significantly increased in rats fed the casein + PSF diet compared to those fed the casein diet, whereas these changes were not observed in rats fed the SPI and the SPI + PSF diets. However, the number of sialo-mucin type goblet cells in the ileum was significantly increased in rats fed the PSF added diets irrespective of the dietary protein source. This was refl ected in the increases in sialic acid content in the mucin fraction and Siat4c expression in the ileum. One might expect the differential Effects of casein and SPI on the mucin secretion stimulated by dietary fiber ingestion to be exerted through the different amino acid pattern in the two proteins.
Soy Protein Research, Japan 13, 85-89, 2010.
Key words : casein, soy protein isolate, polystyrene foam, mucin, goblet cell.
31-15
Exhaustive Analysis of Peptides Derived from Soybean Protein with Bile Acids Binding Ability and
Efficient Modifi cation of VAWWMY Activity by Use of the Peptide Array
Satoshi NAGAOKA1 , Ryuji KATO2 , Mina OKOCHI2 and Hiroyuki HONDA2
1 Faculty of Applied Biological Sciences, Gifu University, Gifu 501-1193
2 Graduate School of Engineering, Nagoya University, Nagoya 464-8603
ABSTRACT
This experiment was designed to identity peptides with bile acid-binding ability from soybean beta-conglycinin. We used the peptide array to evaluate the bile acidbinding ability of peptide derived from soybean beta-conglycinin (hydrophobicity > 0.8). In the peptide array, bile acid-binding ability was evaluated for the binding ability of taurocholic acid and fi xed peptides on cellulose membrane, then binding peptides with taurocholic acid were detected by the first antibody of bile acid, and fi nally the antibody-taurocholic acid complexes were detected by the second antibody. We found some bile acid binding peptides in this screening. Furthermore, we evaluated the effi cient modifi cation of VAWWMY (soystatin) activity by using the peptide array. In this context, we selected PWWWMY, IPWYFY, VIWWFK, IYWYMY to evaluate bile acid-binding capacity and micellar solubility of cholesterol in vitro . VIWWFK had higher bile acid-binding capacity in vitro than did other synthesized peptides. PWWWMY or VIWWFK had significantly lower micellar solubility of cholesterol than other peptides. In rats, the uptake of cholesterol was significantly decreased by the administration of PWWWMY or VIWWFK. We found PWWWMY or VIWWFK had significantly decreased micellar solubility and inhibited cholesterol absorption in ras.
Soy Protein Research, Japan 13, 90-95, 2010.
Key words : beta-conglycinin, peptide array, PWWWMY, VIWWFK, soystatin, bile acid
31-16
Inhibition of Yeast Lipid Body Formation by Soy Peptides
Shingo IZAWA
Graduate School of Scientifi c Technology, Kyoto Institute of Technology, Kyoto 606-8585
ABSTRACT
Excess lipid is neutralized by acylation and accumulates in the lipid body (lipid particle, lipid droplet) as triacylglycerol or sterol ester. We have previously reported that the cultivation of yeast cells in media containing soy peptides prevents the formation of lipid bodies. Compared with yeast cells cultured with casein peptone, cells cultured with soy peptides showed fewer intracellular lipid bodies. In this study, we investigated the Effects of soy peptides on the lipid metabolisms using DNA microarray analysis. The cultivation with soy peptides resulted in decreased levels of mRNA of lipid synthesis and acylation-related genes such as DGA1 , whereas the transcription of glycogen synthesis-related genes such as GLC3 and GSY1/2 was activated. These results suggest that the cultivation with soy peptides might facilitate the formation of glycogen but not the lipid bodies as an energy storage system.
Soy Protein Research, Japan 13, 96-100, 2010.
Key words : soy peptides, baker's yeast, glycogen, lipid particle, DNA microarray
31-17
Effects of a Soybean Component on Zinc Absorption Using Molecular Biological Approach
Taiho KAMBE
Graduate School of Biostudies, Kyoto University, Kyoto 606-8502
ABSTRACT
The zinc transporter ZIP4 (SLC39A4) is essential for zinc absorption. The ZIP4 gene is mutated in humans in the rare, autosomal recessive genetic disease acrodermatitis enteropathica, which is well known as the only severe zinc deficiency. ZIP4 is dynamically regulated by multiple post-transcriptional mechanisms. In zinc deficiency, ZIP4 protein levels are increased and localized on the apical membranes after the extracellular amino-terminal half of the protein is proteolytically cleaved. Administration of an oral gavage of zinc caused ZIP4 internalization and degradation in enterocytes. We found that similar responses were observed in ZIP4 expressed in cultured mouse Hepa cells; ZIP4 is induced by zinc deficiency and degraded in response to added zinc. Here, we generated the anti-ZIP4 monoclonal antibody that specifically recognizes ZIP4 and established a rapid screening system using it and Hepa cells to identify a soybean component that increases ZIP4 expression, which should be a potential enhancer of zinc absorption in the intestinal epithelial cells. We found that Soyafl avone HG, the initial component of which is Isoflavone, includes the factor(s) enhancing ZIP4 expression by the use of this screening system, suggesting soyaflavone HG may contain a factor(s) enhancing zinc absorption.
Soy Protein Research, Japan 13, 101-104, 2010.
Key words : zinc transporter, ZIP4, Hepa cells, absorption, soy Isoflavone
31-18
Research and Application of Bioactive Peptide Derived from Soy Protein with Anxiolytic-Like Activity
Kousaku OHINATA, Aya MURAKI, Mariko OIE, Yuko YAMADA and Masaaki YOSHIKAWA
Graduate School of Agriculture, Kyoto University, Uji 611-0011
Graduate School of Engineering, Osaka University, Suita 565-0871
ABSTRACT
It is known that excess mental stress increases risk of lifestyle-related disease. In the current study, we investigated the eff ect of soymorphin-5 (10 mg/kg/day for 5 weeks, p.o), an anxiolytic peptide derived from soy β-conglycinin β-subunit, on glucose and lipid metabolism using KK-Ay mice, a diabetes model animal. We found that soymorphin-5 ameliorated hyperglycemia 4-5 weeks after the start of oral administration. difference of food intake between soymorphin-5 and control groups was not observed during the experimental period. Soymorphin-5 administration for 5 weeks decreased plasma insulin levels, suggesting that insulin resistance might be improved. Plasma triglyceride (TG) levels and liver weight decreased, and liver TG contents tended to be lower after soymorphin-5 administration. Thus we found that soymorphin-5 improves both glucose and lipid metabolism. Soymorphin-5 also increased plasma adiponectin concentration and liver mRNA expression of peroxisome proliferator-activated receptor (PPAR)α and its target genes. Taken together, orally administered soymorphin-5 may improve glucose and lipid metabolism via activation of adiponectin and PPARα followed by increases of β-oxidation and energy expenditure in KK-Ay mice.
Soy Protein Research, Japan 13, 105-108, 2010.
Key words : β-conglycinin, soymorphin, anxiolytic activity, anti-diabetes, insulin resistance
31-19
Effect of Soy Peptide Ingestion on the Free Amino Acid Contents in Adult Brain of Genetic Serine
Deficiency Model Mice
Shigeki FURUYA
Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University, Fukuoka 812-8581
ABSTRACT
Dietary ingestion of soy proteins has been proven successful at improving several disease-related parameters including blood pressure and insulin sensitivity. However, the Effects of dietary soy proteins on brain are less well described. The aim of this study was to assess effects of dietary soy peptide administration on free amino acid levels in the brain of genetic serine deficiency model and C57BL/6 wild type mice. We compared the Effects of oral ingestion of soy peptide mixture (Hinute-AM), which is mainly composed of di- and tripeptides, and L-serine alone at a equimolar concentration of that in Hinute-AM. After 9 hours' free oral ingestion of Hinute-AM or L-serine solution, cerebral cortex, hippocampus, hypothalamus, cerebellum, and blood were sampled to analyze amino acid concentrations. L- and D-Serine contents in the brain of genetic serine deficiency model mice, which were markedly lower compared to that of C57BL/6 mice, were more increased after ingestion of L-serine in four brain regions examined, compared to Hinute-AM. However, the ingestion of Hinute-AM significantly enhance tissue contents of some amino acids including branched-chain amino acids and some neurotransmitters/ modulators in the cerebral cortex and hippocampus of the model mice. The L-serine ingestion did not alter these amino acids. We observed similar Effects of Hinute-AM on the amino acid contents in the cerebral cortex and hippocampus of C57BL/6 mice. The present observations leads to the possibility that increased amino acids derived from soy peptides may have some benefi cial Effects on brain functions.
Soy Protein Research, Japan 13, 109-115, 2010.
Key words : soy peptide, serine deficiency, brain, disease model, D,L-amino acid analysis.
31-20
Identification of Soy Protein-Derived Hypolipidemic Peptide-Sequences Using in vitro and in vivo Systems
Koji NAGAO*1 , Nao INOUE1 , Kotaro SAKATA1 , Naomi YAMANO1 , Toshiro MATSUI2 and Teruyoshi YANAGITA1
1 Faculty of Agriculture, Saga University, Saga 840-8502,
2 Faculty of Agriculture, Graduate School of Kyushu University, Fukuoka 812-8581.
ABSTRACT
Soy protein is one of the vegetable proteins examined extensively for lipid lowering eff ect in humans and in experimental animals. Although soy protein isolate contains certain amounts of bioactive peptides which have distinct physiological activities in lipid metabolism, it is not clear which peptides are responsible for these Effects. In the present study we have investigated the eff ect of soy protein-derived peptides on lipid metabolism in HepG2 cells and obese OLETF rats. In previous experiments, we found that soy crude protein (SCP-LD3) and hydrophilic peptides (separated from SCP-LD3 with hydrophobic synthetic absorbent) showed lipid lowering Effects in HepG2 cells and in OLETF rats. Moreover, we found that F4 peptides (fractionated from hydrophilic peptides by GPC-HPLC) and 0% CH3CN/0.1% TFAfraction (isolated from F4 peptides by ODS column chromatography) showed hypolipidemic effects in HepG2 cells. In the present study, we found that three di-peptides reduced TG synthesis and one di-peptide reduced apoB secretion in HepG2 cells. In conclusion, we may have isolated active di-peptide sequences of lipid lowering Effects from soy protein.
Soy Protein Research, Japan 13, 116-119, 2010.
Key words : Soy peptide, HepG2 cell, triglyceride, apolipoprotein B-100
31-21
Analysis of the Effect of Soybean Isoflavones on the Function of BRCA1 in Cancer Prevention and Therapy
Risa KASHIWAGI, Ayako MATSUZAWA, Emiko MASEKI, Shun SHIBATA, Yumiko FURUKAWA and Natsuko CHIBA
Department of Molecular Immunology Institute of Development, Aging and Cancer, Tohoku University, Sendai 981-8575
ABSTRACT
The Breast cancer-associated gene 1 (BRCA1) is the most frequently mutated tumor suppressor gene found in familial breast cancers. The risk of breast cancer developing is about 80% in carriers of BRCA1 mutation. Although somatic BRCA1 mutations are rarely observed in sporadic breast cancer, the expression of BRCA1 is down regulated in sporadic breast cancer. Furthermore, gene expression analysis revealed that basal-like subtypes show a profi le similar to that of BRCA1-related cancers. Therefore, lower expression or function of BRCA1 is thought be an important contributing factor in sporadic cancers. In Eastern countries, the risk of breast cancer is lower than in Western countries. A number of studies have shown that this reduced risk may be associated with a high amount of soy consumption. The active inhibitory components of soy are thought to be isoflavones, such as genistein. Recently, it has been reported that genistein inhibits cell proliferation through activation of DNA damage checkpoints, cell cycle arrest, and mitotic catastrophe in BRCA1 -deficient cells. Here, we report that genistein inhibits the accumulation of BRCA1 and other DNA repair factors at the DNA lesions induced by laser micro-irradiation. These findings suggest that genistein suppresses the cellular response to DNA damage. Recently, we have identified a novel BRCA1- associated protein by proteomic study and found that this molecule is localized at the centrosome in interphase, at the spindle poles in the mitotic phase, and at the midbody in cytokinesis. We have established cells that express siRNA of this molecule. Treatment of the cells with genistein significantly increased the multinuclear cells, suggesting that genistein abolish cytokinesis in these moleculedeficient cells. This indicates that genistein affects the BRCA1-related cellular function in the DNA damage response and the regulation of mitosis.
Soy Protein Research, Japan 13, 120-124, 2010.
Key words : isoflavone, genistein, BRCA1, DNA repair, cell cycle regulation
31-22
The Protective Eff ect of Genistain in Charcot-Marie-Tooth Disease
Junji YAMAUCHI
Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo 157-8535
ABSTRACT
Charcot-Marie-Tooth (CMT) disease is the most common inherited neuropathy (1/2,500 people) of the peripheral nervous system (PNS) and is genetically and clinically heterogenous. CMT disease is characterized by progressive sensory neuron loss, and weakness beginning first in the legs and latter in the hands. Based on nerve electrophysiology, most patients with CMT are categorized into two major types: CMT disease type 1 (CMT1) and CMT disease type 2 (CMT2). Recent molecular genetic investigations have established that clinical and neurophysiological features of the different CMT subtypes are largely associated with defects of different types of genes. In CMT1, nerve conduction velocity is less than 38 m/s. The genes involved in CMT1 participate in Schwann cell development and maintenance of myelin structure. CMT2 has preserved nerve condensation velocity but decreased action potentials, showing frequent loss of nerve fibers. The genes responsible for CMT2 appear to constitute molecular connections necessary for axonal stability. Although many CMT disease-responsible genes and mutations have been identified, it still remains to be understood what compound protects against nerve fiber loss and how it helps to reverse it. We recently established the in-vitro dismyelinating model of CMT1 subtype A, the most frequent CMT1. We herein identify that genistain, a soybean product, greatly helps to improve the invitro model. Furthermore, we find that this eff ect is mediated by the neurotrophinneurotrophin receptor system and the downstream signaling pathway. As far as we could ascertain, this is the fi rst report that a soybean product can protect against CMT1.
Soy Protein Research, Japan 13, 125-127, 2010.
Key words : Charcot-Marie-Tooth disease, peripheral neuropathy, genistein, protein kinase
31-23
Effect of Soy Protein β-Conglycinin on Nonalcoholic Fatty Liver Disease
Tomomi YAMAZAKI
National Institute of Health and Nutrition, Tokyo 162-8636
ABSTRACT
Diets high in sucrose/fructose or fat can result in hepatic steatosis (fatty liver). Mice fed a high-fat diet, especially one of saturated fat-rich oil, develop fatty liver with an increase in PPARγ2 protein in the liver. The fatty liver induced by a high-fat diet is improved by knockdown of liver PPARγ2. In this study, we investigated whether β-conglycinin (a major protein of soy protein) could reduce PPARγ2 protein and prevent high-fat-diet-induced fatty liver in ddY mice. Mice were fed a high saffl ower oil (60 en%) or a butter diet (60 en%) for 11 weeks, from which fatty liver is developed. As a control, mice were fed a high-starch diet with drinking water. Either β-conglycinin or casein (control) was given as dietary protein. β-conglycinin supplementation completely prevented fatty liver induced by each type of diet. β-conglycinin decreased PPARγ2 mRNA in mice fed a highfat (saffl ower oil or butter) diet with concomitant decreases in their target genes. β-conglycinin decreased PPARγ2 protein and liver TG concentration in a dosedependent manner in mice fed a high-butter diet; a significant decrease in liver TG concentration was observed at a concentration of 15 en%. Conclusion : A dietary compound that reduces liver PPARγ2 was found. β-conglycinin effectively prevents the fatty liver induced by a high-fat diet through a decrease in liver PPARγ2 protein.
Soy Protein Research, Japan 13, 128-132, 2010.
Key words : fatty liver, β-conglycinin, sucrose, high-fat diet, PPARγ2
31-24
Effect of Serine Protease Inhibitor on Muscle Atrophy
Takeshi NIKAWA*, Arisa OCHI, Takahiro OTO, Tomonari YAMA, Ayako OHNO-MAITA, Akiko HARADA-SUKENO, Reiko NAKAO and Yuushi OKUMURA
Institute of Health Biosciences, The University of Tokushima, Tokushima 770-8503
ABSTRACT
Skeletal muscle is the most sensitive organ to mechanical stress. However, the sensing mechanisms of mechanical stress in skeletal muscles are not completely understood. In our previous studies, we revealed that the induction and activation of ubiquitin ligase Cbl-b played an important role in skeletal muscle atrophy. We next analyzed the signaling and transcription pathway that regulates Cbl-b expression in C2C12 cells using three-dimenstonal(3D)-clinorotation, a simulated-model of microgravity. As the result, Cbl-b expression was regulated by oxidative stress and Egr activation through ERK dependent pathway. In addition, we revealed that this signaling pathway was activated by myostatin. Thus, in the present study, we tried to understand the molecular mechanisms of unloading stress perception, focusing on the activation mechanism of myostatin. Proteolysis activation is required for the activation of myostatin. Myostatin is processed at the cleavage site (Arg-Ser-Arg- Arg:RSRR) by proteases which selectively recognize it. As the candidate processing proteases, we proposed MSPL (the typeII transmembrane serine proteases), proprotein convertase (PC) family member, Furin, PACE4, PC5/6, PC7/8. In fact, MSPL, Furin, PACE4 and PC5/6 activated myostatin in coexpression system to cells. However, the expression of these proteases was not affected by unloading stress. Therefore, the activation of myostatin might be depended on the enhancement of protease activity by unloading stress.
Soy Protein Research, Japan 13, 133-138, 2010.
Key words : mechanosensing, unloading stress, ubiquitin ligase, Cbl-b, myostatin
31-25
Metabolomics Platform for Metabolic Systems Analysis in Leguminous Plant
Yuji SAWADA
RIKEN Plant Science Center, Yokohama 230-0045
ABSTRACT
Diverse metabolites in seed of leguminous plant are important for physiological factions and commercial values. The achievements of detailed metabolite profi ling of seeds have been attracted many researchers in wide range of fi elds. The seed stocks of experimental model plant and crop plant are available from bioresource center, and the metabolome data of them have great potential to directly elucidate plant metabolic systems. More than 90% metabolites in the plant are still unknown, and the un-targeted metabolomics, which is based on the all detectable metabolite, are major methodology. Unfortunately, the un-targeted metabolomics was not appropriate for the practical analysis of the large-scale samples, because of the huge data processing for the un-known metabolites. Thus, we have established a novel practical methodology for metabolomics to quantify hundreds of targeted metabolites, which are based on the reference data of standard compounds, and the simple data processing and high selectivity/sensitivity represent a significant advance as compared to un-targeted metabolomics. Using the reference data of approx. 700 standard compounds, more than 200 metabolites can detected in the representative plant. In this study, we established metabolomics platform for leguminous plant. The metabolites accumulation patterns of crop leguminous plants were analyzed using hierarchical clustering and principal compound analysis. The quantitative trait locus analysis with metabolites as phenotype was carried out using recombinant inbred line of Lotus japonicus . These results can allow us to study the metabolic systems for leguminous plants.
Soy Protein Research, Japan 13, 139-144, 2010.
Key words : Metabolomics, widely targeted metabolomics, leguminous plant, LC-MS
31-26
Solubilization and Stabilization of Dextran-Introduced Soy Protein Isolate by Transferase Reaction
Hidetaka KAWAKITA
Department of Applied Chemistry, Saga University, Saga 840-8502
ABSTRACT
Dextransucrase is immobilized on the surface of soy protein isolate (SPI) via electrostatic interaction. In reacting with sucrose, dextran is generated from the immobilized DSase. Dextran-generated SPI had higher stability and viscosity in solution, demonstrating that water molecules coordinated with the generated dextran. Using the enzymatic reaction, a novel method to modify surface of a biocolloid such as SPI was developed.
Soy Protein Research, Japan 13, 145-148, 2010.
Key words : dextransucrase, SPI, dextran viscosity
31-27
Regulation of Protein Digestibility of Soybean Meal by Tannins in Ruminant Feedstuffs
Makoto KONDO
Graduate School of Bioresources, Mie University, Tsu 514-8507
ABSTRACT
The current experiment was conducted to study the effect of different types of tannin on ruminal degradation and post-ruminal digestion of treated soya bean meals (SBM) with respect to in vitro and in vivo digestibility. Samples of SBM were prepared by spraying 100 g SBM with distilled water containing 10 g of 6 types of tannin extracted from tara, gambier, chestnut, myrabolam, quebracho, and mimosa. Rumen degradability of tannin-treated SBM was significantly decreased and intestinal digestibility of the protein was slightly suppressed. As a result, digestible rumen undegradable protein (RUP) was high in SBM treated with tannins, especially chestnut and myrabolam. In comparison to commercial soybean feedstuff s, these tannin-treated SBM wore similar or higher in digestible RUP content. In the next experiment, in vivo digestibility, nitrogen balance and ruminal NH3-N concentration in goats fed SBM treated with chestnut or tannin were determined. Protein digestibility, urinary N excretion and ruminal NH3 concentration were not affected by the tannin treatment. It was therefore concluded that tannin treatment of SBM effectively improved protein utilization of SBM in vitro but not in vivo. Further research is required to bind SBM proteins to tannins strongly enough to regulate protein digestibility in ruminants.
Soy Protein Research, Japan 13, 149-153, 2010.
Key words :soybean meal, ruminant, protein degradability, tannin
31-28
Effect of Dietary Fermented Soybean on Physical Endurance in Mice
Nakamichi WATANABE and Satomi SAKUDA
Department of Food Science and Nutrition, Showa Women's University, Tokyo 154-8533
ABSTRACT
Studies presented at the 6th International Symposium on the Role of Soy, 2005, reported that dietary soybean increased physical endurance because of decreased plasma lipid peroxidation. Our previous studies, performed using assays, such as the balk system, emulsion system, red blood cells ghost system, and plasma system, have shown that the antioxidant activities of tempeh were stronger than that of non-fermented soybean. Therefore, compared to the intake of non-fermented soybean, the intake of fermented soybean products, such as tempeh, was expected to increase physical endurance. In this study, we examined the eff ect of dietary nonfermented soybean and tempeh on physical endurance and fatigue by subjecting Balb/c mice to a swimming test. Intake of non-fermented soybean decreased the blood lactate levels and plasma creatine kinase activities, but the swimming time was not affected. In contrast, and unfortunately, the intake of tempeh had no eff ect on physical endurance and fatigue; however, it did cause a decrease in plasma lipid peroxidation. In the mice fed non-fermented soybean, the plasma free fatty acid levels increased and the glycogen content in the skeletal muscles decreased, but the glycogen content in the liver did not decrease. These results suggested that the decrease in fatigue caused by dietary non-fermented soybean might be induced by improved utilization of glycogen in the skeletal muscles and fatty acid in the adipose tissue as energy sources.
Soy Protein Research, Japan 13, 154-158, 2010.
Key words : fatigue, physical endurance, soybean, tempeh
31-29
Analysis of Autonomic Control Mechanism by Protein Component of Soy Bean
Mamoru TANIDA*, Mie KOMATSU and Jun SATOMI
Department of Biomedical Sciences, College of Life Sciences, Ritsumeikan University, Kusatsu 525
ABSTRACT
It has been known that there are some bitter components of soy bean. In the study presented here, we examined the autonomic effects of taste stimulation with saponin, or isofl avon, bitter components of soy bean, and of intragastric (IG) injection of these components in urethane-anesthetized rats. Taste stimulation with saponin or isoflavon solution (S-HG) did not affect autonomic nerve activity such as sympathetic nerve activity innervating adrenal grand (ASNA) and gastric vagal nerve activity (GVNA). On the other hand, IG injection of S-HG increased ASNA, while it suppressed GVNA. Furthermore, S-HG drinking for 14 d reduced body weight gain and food intake in rats. These results thus suggest that isofl avon supplementation exerts its reducing action on body weight through changes in autonomic neurotransmission.
Soy Protein Research, Japan 13, 159-163, 2010.
Key words :Sympathetic nerve, rats, parasympathetic nerve, appetite, electrophysiology
31-30
Analysis of the Effects of Soybean on Phagocytosis Against Cancer Cells
Kaz NAGAOSA
Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kanazawa 920-1192
ABSTRACT
We investigated whether soy peptide was effective in down-regulation of carcinogenic risk by using Drosophila melanogaster as a model for cancer research. Precancerous cells must induce apoptosis and be engulfed by phagocytes to prevent carcinogenesis, and this removal is believed to occur by a cell competition-related mechanism. It has been reported that a Drosophila cell in which cell competition has failed grows more slowly than a normal cell. In our study, phagocytosis of apoptopic cells by macrophages was down-regulated in soy peptide-treated Drosophila . The developmental period from embryo to adult was also delayed by feeding soy peptide. Furthermore, fewer of these Drosophila reached adulthood compared with ones fed normal food. These results suggest that soy peptide may suppress cell competition and have a negative eff ect on phagocytosis, growth rate, and normal development. Further study is needed to clarify whether soy peptide decreases carcinogenic risk.
Soy Protein Research, Japan 13, 164-168, 2010.
Key words :soy peptide, phagocytosis, cancer, cell competition, Drosophila
31-31
Synergistic Effect of Amino Acids on Antioxidative Stress Activity of Soyasaponins
Shigeru KATAYAMA, Fumi KUROIWA and Soichiro NAKAMURA
Department of Bioscience and Biotechnology, Shinshu University, Nagano 399-4598
ABSTRACT
Excessive generation of reactive oxygen species (ROS) has a deleterious effect on human health since they can damage cell structure involved in the cellular lipids, membranes, proteins, and DNA. Many environmental factors including food intake can lead to increased resistance to oxidative tissue injury. Soybeans have long been recognized as an excellent source of high-quality protein and potent bioactive compounds such as saponins and Isoflavone. The objective of this study is to evaluate the antioxidative stress activity of soyasaponins (Soyhealth SA) and the synergistic eff ect of amino acids in in vitro assay using human hepatoma cell lines, HepG2. The cells were stimulated with 1 mM tert-butyl hydroperoxide (t -BOOH) for 3 h. The inhibition of t -BOOH-induced cellular ROS generation and of malondialdehyde (MDA) formation in HepG2 cells was observed in the pretreatment with soyasaponin for 20 h. We also observed that mRNA expression of the catalytic and modulatory subunits of glutamate cysteine ligase (GCLc and GCLm), the rate-limiting enzymes for de novo GSH synthesis, including as well as GSH synthetase was up-regulated by the treatment with soyasaponin. On the other hand, the synergistic, eff ect of amino acid was observed in the addition of Met and Val. The simultaneous addition of Met or Val with soyasaponin exhibited marked increases in the mRNA expression of GSH synthesis-related enzymes. These results indicated that soyasaponin exhibited the oxidative stress modulating effect in HepG2 cells and its eff ect was enhanced when combined with the particular amino acid.
Soy Protein Research, Japan 13, 169-174, 2010.
Key words :soyasaponin, amino acids, GSH, oxidative stress, Nrf2
31-32
Soybean Isoflavones Inhibit Amyloid β-protein Self-Assembly
Mie HIROHATA1, 2 , Kenjiro ONO1 , Tokuhei IKEDA1 , Akiyoshi MORINAGA1 , Junichi TAKAZAKI1 and Masahito YAMADA1
1 Department of Neurology and Neurobiology of Aging, Kanazawa University Graduate School of Medical Science, Kanazawa 920-8641,
2 Department of Neurology, National Hospital Organization Iou Hospital, Kanazawa 920-0192
ABSTRACT
Epidemiological evidences from retrospective and case-control studies has indicated that estrogen replacement therapy can decrease the risk of developing Alzheimer's disease. Soybean Isoflavones have been proposed as phytoestrogens, because some of isoflavones were reported to exert a neuroprotective effect against β-amyloid protein (Aβ)-induced neurotoxicity. Recently, our experimental studies have demonstrated that some kinds of flavonoids and estrogens inhibited Aβ assembly and destabilized Aβ aggregates. To examine the effects of isoflavones on the assembly of the two predominant disease-related Aβ alloforms, Aβ1-42 and Aβ1-40, here we used thioflavin T fluorescence, electron microscopy, and photo-induced cross-linking of unmodifi ed proteins (PICUP) followed by SDS-PAGE. Initial studies revealed that some kinds of isoflavones blocked Aβ fibril formation. Subsequent evaluation of the assembly stage specificity of the eff ect showed that Isoflavones were able to inhibit pre-protofibrillar oligomerization. These data suggest that Isoflavones would be worthy of consideration as a therapeutic agent for Alzheimer's disease.
Soy Protein Research, Japan 13, 175-181, 2010.
Key words :Alzheimer's disease, amyloid β-protein fi brils; Isoflavone; oligomerization; photo-induced cross-linking of unmodifi ed proteins (PICUP)
31-33
Effect of Soy Isoflavones on Cyclooxygenase Activity
Yuki KAWAKAMI and Yoshitaka TAKAHASHI
Faculty of Health and Welfare Science, Okayama Prefectural University, Soja 719-1197
ABSTRACT
Cyclooxygenase (COX) is the key enzyme responsible for the production of prostaglandin and thromboxane, which play important roles in inflammation and carcinogenesis. Because soy Isoflavones are known to have a variety of benefi cial Effects on our body including the antioxidative activity, we investigated whether soy isoflavones inhibited the catalytic activity of the two COX isoforms using linoleic acid as an alternative substrate. Genistein dose-dependently inhibited the COX activity of human COX-1 and COX-2 as assessed by conversion of linoleic acid to 9- and 13-hydroxyoctadecadienoic acids. The IC50 values for COX-1 and COX-2 were 28 and 110μM, respectively. The Lineweaver-Burk plot analysis of the apparent initial velocity as measured by 30-s reaction of purified ovine COX-1 with linoleic acid in the presence of various concentrations of genistein suggested that the inhibition of the enzyme by genistein was apparently noncompetitive.
Soy Protein Research, Japan 13, 182-186, 2010.
Key words :Cyclooxygenase; Soy Isoflavone; Enzyme acitivity
31-34
Protective Effect of Soy Isoflavone Genistein on Ischemia-Reperfusion Injury
Shiro ITAGAKI
Division of Pharmacy, Hirosaki University school of Medicine and Hospital, Hirosaki 036-8563
ABSTRACT
Reperfusion injury refers to damage to tissue caused when blood supply returns to the tissue after a period of ischemia. Ischemia-reperfusion (I/R) injury has been well described in the literature as causing organ damage in the brain, heart, lungs, liver, kidneys and skeletal muscle. Intestinal I/R is a common clinical problem in the settings of severe burns, circulatory shock and strangulation ileus. Indeed intestinal I/R injury is an important factor associated with high morbidity and mortality. Intestinal I/R damages remote organs and promote multi-organ failure. It has been reported that enteral feeding before ischemic insults is benefi cial for reducing organ injury and improving survival after intestinal I/R. In that study, the authors used a standard complex enteral diet and they suggested that it is important to find new nutrient formulas. Since reactive oxygen species are responsible for intestinal I/ R injury, we focused on the soy Isoflavone genistein, which has a wide spectrum of biochemical and pharmacological activities. In this study, we have found that genistein, which has combined antioxidant activity from radical scavenging, xanthine oxidase inhibition and chain-breaking Effects, exhibits a protective eff ect on intestinal I/R injury.
Soy Protein Research, Japan 13, 187-191, 2010.
Key words :ischemia-reperfusion; intestine; genistein; antioxidant;
Soy Protein Research (Japan)