The Multivariate Functions of Adipose Tissue and the Metabolic Syndrome :
The Effects of Soybean Protein on Fat Distribution and Adipocytokines
Yuji MATSUZAWA
Osaka University Graduate School of Medicine, Suita 565-0871
ABSTRACT
The metabolic syndrome, which clusters insulin resistance, dyslipidemia, and hypertension
in each individual is a common basis of type 2 diabetes and atherosclerotic vascular
diseases. Accumulation of intra-abdominal visceral adipose tissue triggers the
metabolic syndrome. Recent researches have explored adipose tissue is not solely
an energy storing tissue but secretes a variety of bioactive substances called
adipocytokines. This study was designed to elucidate the role of adipose-expressed
genes in the development of the metabolic syndrome, and the significance of soybean
protein, which is a major component of classical Japanese diet, on the regulation
of the genes in adipocyte. Through the extensive analysis of adipose-expressed
genes, we isolated several adipose-specific genes, galectin-12, adiponectin, and
aquaporin adipose. Forced expression of galectin-12 induced cellular apoptosis.
Although the significance of apoptosis in adipose tissue remains unclear, galectin-12
may work to determine the cell size and the capacity of buffer action against
nutritional overload. Adiponectin is a plasma protein having insulin sensitizing
activity and modulating vascular functions, but plasma adiponectin levels were
decreased in the subjects with body fat accumulation. Promoter analysis revealed
that TNF-a decreased and PPARg-ligands
increased the expression of adiponectin. Aquaporin adipose, a channel forming
integral protein, works as a glycerol channel in adipocyte. The expression of
aquaporin adipose decreased in the feeding state, in which glycerol release was
suppressed. This suppression was achieved by insulin responsive element in its
promoter. In the obese animals, the expression of aquaporin adipose was augmented
leading to the enhanced glycerol release from adipocytes. Diet therapy with soybean
protein in obese mice reduced body fat and increased plasma adiponectin, resulting
in the improvement of glucose tolerance. These results suggested that dysregulation
of adipose-specific genes relates to the pathogenesis of the metabolic syndrome.
soybean protein may improve the dysregulation and prevent the metabolic syndrome.
Soy Protein Research, Japan5 1-9, 2002.
Key words : soybean protein, adipocytokine, visceral fat, metabolic syndrome
1Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589 2Cryobiosystem Research Center, Faculty of Agriculture, Iwate University, Iwate 020-8550
ABSTRACT
The 7S globulin (b-conglycinin), a major component
of seed storage proteins in soybean, comprises three subunits, a,
a' and b. In order to clarify
the molecular mechanisms of gene expression of seed storage proteins, changes
in the pattern of DNA-protein interaction during the process of seed maturation
were analyzed. We examined the protein-binding on the Box I element, which is
located in the upstream of the gene encoding a subunit
and is considered to be involved in the transcriptional regulation of the a
subunit gene. An increase in the amount of DNA-protein complex was detected
using nuclear proteins isolated from seeds with increasing period of seed-maturation
(27, 34, and 42 days after flowering) by a gel-shift assay. ince the transcriptional
activity of the a subunit gene increased with an increasing
period of seed-maturation, these Box I binding proteins were considered to be
involved in positive regulation of transcription. Box I-binding proteins that
were different from those exist in the seeds were detected in the nuclear extracts
from leaves. In addition, CG-2, a gene located in the vicinity of the a
subunit gene in a soybean cultivar 'Forrest', was found to share high sequence-homology
with the a subunit gene. Deletion of the CG-2 was detected
in the genome of a cultivar 'Keburi' in addition to the deletion of a'
subunit gene. Soy Protein Research, Japan5 10-16, 2002.
Key words : soybean, b-conglycinin, a
subunit, DNA-protein interaction, deletion
Metabolism of the Precursor of Gly m Bd 28K, a Major Soybean Allergen in Growing Soybean Seeds
Hideaki TSUJI1, Miki HIEMORI1, Masumi KIMOTO1 and Shigeru UTSUMI2
1Faculty of Health and Welfare Science, Okayama Prefectural University, Soja 719-1197 2Graduate School of Agriculture, Kyoto University, Uji 611-0011
ABSTRACT
Gly m Bd 28K is biosynthesized as a preproprotein, which is suggested to be metabolized
to form Gly m Bd 28K and its C-terminal peptide (23 kDa peptide) during the growth
of soybean seeds. In the present study, Gly m Bd 28K and the tentative 23 kDa
peptide were examined in order to elucidate the metabolism of the precursor of
Gly m Bd 28K in growing soybean seeds. Monoclonal antibodies (mAbs) recognizing
the 23 kDa peptide were prepared. The 23 kDa peptide was detected using an immunoblotting
technique with one of the mAbs. N-terminal amino acid sequence of the peptide
was shown to be KDTAGSPASYNLYDDKADF. This result shows that the 23 kDa peptide
corresponds to sequence 267-473 on the amino acid sequence of the precursor of
Gly m Bd 28K. Furthermore, Gly m Bd 28K and the 23 kDa peptide were shown to be
localized in the protein bodies in growing soybean seeds by gold colloidal method
with the mAb. Soy Protein Research, Japan5 17-20, 2002.
Key words : soybean allergen, Gly m Bd 28K, preproprotein, allergenicity
Elucidation of Structure- physicochemical Function Relationships at Subunit Level of Soybean Glycinin by Using Mutant Cultivars
Nobuyuki MARUYAMA and Shigeru UTSUMI
Graduate School of Agriculture, Kyoto University, Uji 611-0011
ABSTRACT
We purified four mutant glycinins composed of only group I subunits (group I),
only group II subunits (group II), only A3B4 subunit (A3B4) and only A5A4B3 subunit
(A5A4B3) from mutant soybean cultivars, and compared their structural features
and physicochemical functions with those of the wild glycinin (11S) from var.
Shirotsurunoko. Thermal stabilities of groups I and II were similar to each other,
although that of A3B4 was significantly lower than the others. The order of surface
hydrophobicities determined by hydrophobic column chromatography was group I <
11S < A5A4B3 < group II < A3B4. Solubility of 11S was an arithmetic mean
of those of groups I and II at low ionic strength (0.08), but that was determined
by group I at high ionic strength (m=0.5). Solubility
of group II was determined by A5A4B3 at both ionic strengths. The order of emulsifying
abilities was group I <11S < A3B4 < group II < A5A4B3. This order
did not correlate with those of thermal stabilities and surface hydrophobicities
of glycinin species. Soy Protein Research, Japan5 21-25, 2002.
Graduate School of Agriculture, Kyoto University, Uji 611-0011
ABSTRACT
RPLKPW is a highly potent anti-hypertensive peptide obtained by replacing four
amino acid residues in ovokinin (2-7) (RADHPF) that is a vasorelaxing peptide
isolated from a chymotryptic digest of ovalbumin. n previous study, RPLKPW sequence
was introduced into three homologous sites in soybean b-conglycinin
a' subunit by site-directed mutagenesis and the mutated
a' subunit expressed in Escherichia coli exerted an
anti-hypertensive effect in spontaneously hypertensive rats at a dose of 10mg/kg
(per os). In this study, we found that RPLKPW was released from only one site
among three RPLKPW-sites by in vitro digestion experiment with model peptides
around RPLKPW-sites of modified a' subunit. In order
to release RPLKPW efficiently, we optimized amino residues around individual RPLKPW-sites.
The yields of RPLKPW from 3 RPLKPW-sites were increased markedly. Furthermore,
we introduced fourth RPLKPW sequence to the a' subunit.
The minimum effective dose of a' subunit containing
four RPLKPW was 2.5mg/kg, about one-fourth of that of modified a'
subunit that we previously reported. The anti-hypertensive activity of a'
subunit containing four RPLKPW was larger than ovalbumin by about eight hundred
times. Soy Protein Research, Japan5 26-30, 2002.
Key words : ovalbumin, anti-hypertensive peptide, soybean b-conglycinin,
spontaneously hypertensive rat, site-directed mutagenesis
Salt-tolerant g-Glutamyltranspeptidase: To Utilize Soy Protein as a Source of Umami Taste
Hideyuki SUZUKI
Graduate School of Biostudies, Kyoto University, Kyoto 606-8502
ABSTRACT
g-Glutamyltranspeptidase (GGT) from Bacillus subtilis
is an extracellular enzyme that exhibits glutaminase activity. As it is only produced
during the mid-stationary phase, a strain overexpressing GGT was generated to
obtain sufficient quantities of GGT. The level of GGT activity of this strain
increased steadily after the exponential phase, becoming 13-fold higher than that
in the parental strain. The recombinant GGT was purified by 107-fold. The enzyme
was a heterodimer consisting of one large subunit (45 kDa) and one small subunit
(21 kDa). The enzyme was highly salt-tolerant and converted glutamine to glutamic
acid effectively even in the presence of 18% NaCl.g Soy Protein Research, Japan 5 31-35, 2002.
Key words : g-glutamyltranspeptidase, Bacillus subtilis,
glutaminase, taste, umami
Analysis for Mechanism of Soybean- milk- coagulation by Bacterial Protease and Utilization of the Enzyme to the Food Processing
Masaaki YASUDA1, Megumi KUBA1, Shinjiro TACHIBANA1 and Misako AOYAMA2
1Faculty of Agriculture, University of the Ryukyus, Okinawa 903-0213 2Faculty of Nursing and Nutrition, Siebold University of Nagasaki, Nagasaki 851-2195
ABSTRACT
The coagulation of protein in soybean milk by serine proteinase from Bacillus
pumilus and utilization of the enzyme to the food processing were examined. The
ratios of precipitated and 4% TCA soluble nitrogen to the total nitrogen increased
with increasing reaction time. In order to elucidate the aspect of protein-degradation
in soybean milk by this enzyme, slab-SDS-PAGE was carried out. The a'-,
a-and b-subunits in b-conglycinin
were degraded gradually. The acidic subunit in glycinin was degraded at an initial
stage (0.5 min) and was completely degraded by the time the coagulation began
(3 min). However, the basic subunit in glycinin still remained even after 30 min.
When the enzyme reacted with the denatured glycinin, precipitation in the reaction
mixture occurred, while this phenomenon was not observed in the case of denatured
b-conglycinin. Therefore, it was considered that degradation
of glycinin played a key part in the coagulation of protein in soybean milk. The
amount of detectable sulfhydryl group in soybean milk reached the maximum just
before the coagulation. The coagula obtained were completely dissolved in the
presence of 0.5% SDS solution without 2-mercaptoethanol. Therefore, it is suggested
that hydrophobic interaction played an important role in the coagulation process.
Soybean protein curd that was prepared by this enzyme with calcium sulfate was
firm, and it is expected to be useful for production of tofuyo. Soy Protein Research, Japan5 36-40, 2002.
Key words : serine proteinase, Bacillus pumilus, soybean-milk-coagulation,
soybean protein curd, tofuyo
Removal of Phytic Acid from Soy Protein Isolates and Its Effect on Protein Functionality
Miki KATOH, Dong-Hao JIN, Takako NAGANUMA, Tomohisa OGAWA and Koji MURAMOTO
Graduate School of Life Sciences, Tohoku University, Sendai 981-8555
ABSTRACT
Soy protein isolates contain about 2% of phytic acid, which is considered as an
antinutrient due to its inhibitory effect on mineral bioavailability. A simple
acid extraction method was developed to reduce phytate content. By extracting
with 0.6 M HCl, 96% of phytic acid could be removed. The acid extraction significantly
changed the gel filtration patterns of soy proteins, however, there was no change
in their subunit compositions on SDS-PAGE. The digestibility of soy proteins with
pepsin not with trypsin improved upon the extraction. The increase of the surface
hydrophobicity of phytate-removed soy proteins resulted in the increase of its
emulsifying activity. Moreover, the hydrolysates derived from phytate-removed
soy proteins accelerated the calcium transport across the Caco-2 cell monolayer. Soy Protein Research, Japan 5 41-46, 2002.
How Does the Radical-scavenging Activity of Soy Protein Food Change during Heating?
Teruyoshi MATOBA
Graduate School of Human Culture, Nara Women's University, Nara 630-8506
ABSTRACT
Soybean contains radical-scavenging activity, which prevents life style-related
diseases. Therefore, soy protein foods are the key foods to maintain human health.
In this paper, the changes in the radical-scavenging activity of soy protein foods
during heating and digestion were determined. Three soy protein fractions (7S
fraction, 11S fraction and lipid-including proteins) were fractionated from defatted
soybean. These fractions and defatted soybean contain high radical-scavenging
activity. The activity did not change during heating. However, enzyme digestion
increased the radical-scavenging activity 3-5 times. The activity after digestion
was almost same level of those in vegetables in dry weight basis. The isoflavone
content did not change during heating or digestion. These results indicate that
the increase in the radical-scavenging activity of soy proteins is due to the
peptides formed in digestion. Soy Protein Research, Japan5 47-50, 2002.
Key words : soybean, soy protein, radical-scavenging activity, isoflavone, peptide
Development of a Novel Foam Food Made from Wheat Flour and Soy Protein Isolate
Keiko FUJII
Department of Food Science and Nutrition, Japan Women's University, Tokyo 112-8681
ABSTRACT
The sponge cake was made with rice flour and soy protein isolate (SPI) as main
components. In the case of no added SPI, the moisture sorption isotherms of sponge
cakes were not affected by aids for foaming. When SPI was added, the equilibrium
moisture contents of the cake were affected by the properties of aids owing to
the greater moisture sorption isotherm of SPI. The cake made with silk fibroin
showed the smallest equilibrium moisture content. It was thought that it reflected
the hydrophobicity of silk fibroin. Drying rate of cake with silk fibroin was
the smallest. These results suggest that fibroin may form the network to prevent
moving of water molecules in the cake. The silk fibroin used was obtained from
waste yarn and showed very interesting characters as described above. It may be
acceptable as foodstuff. Soy Protein Research, Japan 5 51-57, 2002.
Key words : sponge cake, rice flour, soy protein isolate, silk fibroin, moisture
sorption isotherm
A Crucial Role of Soybean Resistant Protein in Increased Fecal Steroid Excretion and Structural Peculiarity of Caught Bile Acids
Kimikazu IWAMI, Naoto FUJII, Tomohiko SUZUKA and Ryuhei KANAMOTO
Graduate School of Agriculture, Kyoto Prefectural University, Kyoto 606-8522
ABSTRACT
Growing male Wistar rats were divided into three groups (n =6), which were fed
the respective SPI (+7%cellulose), HMF (no cellulose) and SPI+RP diets with supplementary
0.5% cholesterol over a period of 4 weeks. In the meantime, the rats were examined
for fecal acidic or neutral steroid excretion and serum total cholesterol concentration
at weekly intervals and for hepatic cholesterol content at the 4th week. There
were no significant variations in serum total cholesterol concentration among
these three groups during the period of feeding, but the difference in fecal acidic
or neutral steroid excretion was significant between both SPI and HMF (or SPI+RP)
groups, being inversely proportional to hepatic cholesterol content. These observations
support the possibility of RP bringing about improvement in cholesterol level
within the body. In this connection, the stereoselectivity of RP for a variety
of bile acids was further inspected by equilibrium dialysis. Consequently RP turned
out to have a different affinity for DCA, CDCA >> HDCA > TDCA, GCDCA,
UDCA, CA in their order. Noteworthily, dihydroxybile acids such as DCA and CDCA
were more effectively captured by RP than their amino acid conjugates (TDCA, GCDCA)
or other analogs (HDCA, UDCA). Taking into account a serious risk of secondary
bile acid in practice, the RP intake favorably serves as a preventive against
tumorigenesis in colon. Soy Protein Research, Japan5 58-62, 2002.
Key words : resistant protein (RP), SPI+RP diet, fecal steroid excretion, equilibrium
dialysis, dihydroxybile acid, cancer prevention
Correlational Analysis of Allergy and Antigenic N-Glycans Linked to Soybean Storage Glycoproteins
Yoshinobu KIMURA
Faculty of Agriculture, Okayama University, Okayama 700-8530
ABSTRACT
Recently many glycoproteinous allergens (glycoallergens) have been identified
from plant food or pollens. In many cases, such glycoallergens bear plant complex
type N-glycans, which have b1-2 xylose and/or a1-3
fucose and show strong antigenicity against mammals. However, correlation of intakes
of such antigenic N-glycans and allergy symptoms remains to be understood. In
this report, the author describes (1) structural analysis of N-glycans linked
to the storage glycoprotein in soybean, showing that the plant complex type N-glycans
(Man3Xyl1Fuc1-0GlcNAc2; 5%) are linked to some soybean glycoproteins, (2) structural
feature of free N-glycans in soybean seedlings, showing that the plant complex
type free N-glycan occurs at the concentration of about 100 pmol/g of fresh weight
of hypocotyl, and (3) allergenicity of the antigenic N-glycans prepared from soybean
glycoproteins from the view point of IgE-binding to the N-glycans, showing that
the plant complex type N-glycans can not be major epitope for IgE in sera of pollinosis
patients. Soy Protein Research, Japan 5 63-67, 2002.
1Graduate School of Agriculture, Kyoto University, Uji 611-0011 2Ota Pediatrics and Allergy Clinic, Takamatsu 761-0101 3Fukuyama Medical Laboratory Co., Ltd., Hukuyama 720-0831
ABSTRACT
In previous report (Soy Protein Research, Japan4 45-51 2001), we
demonstrated that the allergic patients sensitized by plant food stuffs such as
soybean have specific IgE antibodies recognizing asparagine-N linked oligo-mannose
type glycan moieties of Man3GluNAc2 backbone with b1-2
xylose branch or b1-2 xylose and a1-3
fucose branches. Sera of these patients showed high cross-reactivity among various
plant food stuffs by radioallergosolvent test (RAST). Accordingly, these patients
often gave false positive diagnostic results about various plant food stuffs that
do not elicit any allergic symptoms. In order to avoid these false positive RAST
diagnoses, especially in case of soybean allergic patients, we tried to develop
the improved RAST procedure using a blocking technique of glycan moieties of glyco-proteins
immobilized on the allergen screening discs applied to RAST automatic analyses.
The improved method demonstrated that the RAST scores of some patients allergic
to plant food stuffs are markedly decreased by blocking sugar moieties of glyco-proteins.
On the other hand, about half of patients examined did not show significant changes
in RAST scores even though using improved method, indicating that they are true
patients against tested foodstuffs and can serve as test challengers for an assessment
of the hypoallergenic processed foods. Soy Protein Research, Japan 5 68-72, 2002.
Key words : soybean allergy, food allergy, radioallergosolvent test (RAST), glycan
moiety, glyco-protein, hypoallergenic soybean products
A Study on the Functions of Dietary Protein on Growth and Differentiation of Neural Stem Cells
Kiwao NAKANO
Nagoya University Bioscience Center, Nagoya 464-8601
ABSTRACT
The effects of systemic administration of tryptophan and its metabolite, kynurenine,
were evaluated on growth and differentiation of neural stem cells in the brain
of mouse. Daily intraperitoneal injection of kynurenine significantly decreased
the number of neural stem cells in the brain of epilepsy-prone EL mouse. In contrast,
it had essentially no effect on C57BL/6, C3H/HeN, ddY nor BALB/c mouse. Addition
of kynurenine caused a marked increase in the synthesis of nerve growth factor
and brain-derived neurotrophic factor in the culture of astrocytes. Together,
these results suggest that tryptophan metabolites, especially kynurenine, stimulate
the differentiation of neural stem cells to neurons and/or glial cells in the
brain of EL mouse through induction of synthesis of neurotrophic factors. These
reactions may be associated, in part, with epileptogenesis of EL mouse. Soy Protein Research, Japan5 73-75, 2002.
Key words : neural stem cell, NGF, kynurenine, epilepsy, EL mouse
Attenuating Effect of Soy Protein and a Semipurified Alcohol Extract of Soy Protein on Glomerular Injury in Spontaneous Hypercholesterolemic Male Imai Rats
1Saga Medical School, Saga 849-8501 2Research and Development Laboratory, Fujicco Co, Kobe 650-855
ABSTRACT
Soy protein has hypercholesterolemic and estrogenic properties. Because the renoprotective
effect of both lipid-lowering agents and estrogen has been reported, we investigated
whether soy protein (in the experiment 1) and soy protein's alcohol-extractable
components (SPEs;mainly consisting of isoflavones) (in the experiment 2) have
an ability to attenuate glomerular injury in male Imai rats in which hypercholesterolemia,
focal and segmental glomerulosclerosis (FSGS) and renal insufficiency occur spontaneously.
In the experiment 1, soy protein diets resulted in less proteinuria, less hyperlipidemia,
less hypoalbuminemia, less renal functional impairment, less glomerular hypertrophy
and less renal histological damage as compared with control casein diet. In the
experiment 2, male Imai rats were fed a casein-based diet with and without SPE.
Group 1 (Cont) was fed standard diet without any additional SPE and groups 2 (SPE-1)
and 3 (SPE-2) were fed standard diet supplemented in amounts of 0.05 and 0.10
g/100 g diet of SPE, respectively. Growth rate was not different among three groups
throughout the experiment. SPE-supplemented diets resulted in less proteinuria
and less hyperlipidemia. The decline in renal function with regard to the levels
of blood urea nitrogen and creatinine clearance was less marked in the animals
receiving the SPE-supplemented diets. Each SPE-supplemented diet equally induced
less glomerular hypertrophy and less renal histological damage as compared with
non-supplemented diet. These studies showed a beneficial effect of soy protein
diet and a semipurified alcohol-extract of soy protein on glomerular disease.
Soy Protein Research, Japan5 76-80, 2002.
Key Words : soy protein, glomerulosclerosis, isoflavones, male rats, estrogen
Effect of Soy Protein Intake on High- fat Induced Obesity and Insulin Resistance
Nobuyo TSUNODA, Yuko FUJIKANE, Hyounju KIM, Midori EBATA and Shinji IKEMOTO
Faculty of Pharmaceutical Sciences, Josai University, Sakato 350-0295
ABSTRACT
High-fat diet feeding leads to obesity and insulin resistance. Recently, it was
reported that sterol regulatory element-binding protein-1c (SREBP-1c) is involved
in this mechanism of high-fat induced obesity and insulin resistance. SREBP-1c
is an important factor regulating cholesterol and fatty acid metabolism. Some
reports suggested soy protein (SPI) also has the effect of decreasing plasma cholesterol
levels. Therefore, SPI may modulate the effect of high-fat on obesity and insulin
resistance and/or SREBP-1c expression level. Furthermore, our previous study demonstrated
levels of high-fat induced obesity and insulin resistance were different by types
of oil. In this study, we investigated whether SPI intake modulates levels of
obesity and insulin resistance induced by high-fat diets composed of three different
oils (safflower oil, fish oil, palm oil). No significant effects are on body weight,
adipose tissue weight and glucose tolerance tests by SPI intake. But insulin tolerance
tests deteriorated in mice fed high-safflower oil diets contained SPI (S-SPHF)
compared with mice fed high-safflower oil diets contained casein (S-HF). S-SPHF-fed
mice had high plasma glucose levels compared with S-HF-fed mice while no difference
of plasma insulin levels was observed. These results indicate that S-SPHF-fed
mice may produce insulin resistance causing decreased glucose uptake by the peripheral
tissues. Furthermore, we found that insulin resistance in S-SPHF-fed mice may
be caused by decreased glucose transporter 4 (GLUT4) mRNA in white adipose tissue.
But it is remained to clear which tissues (skeletal muscle or adipose tissue or
liver) relate to insulin resistance. Soy Protein Research, Japan5 81-85, 2002.
Key words : soy protein(SPI), oils, obesity, insulin resistance
1Graduate School of Science and Technology, Kobe University, Kobe 657-8501 2Nihon Nosan Kogyo K. K., Yokohama 220-8146
ABSTRACT
As a link in the chain of the discovery of physiologically active components of
soybean protein in chicks, the present study was conducted to evaluate the effects
of soy protein isolate and its enzymatic hydrolysate on body fat deposition in
chicks. Firstly, chicks were fed with an 18% casein, soy protein isolate (SPI)
or enzymatic hydrolysate of SPI for 3 weeks, and the comparative effects of soybean
proteins on growth performance, adipose tissue weight, the triglyceride contents
of plasma and liver were examined. SPI and enzymatic hydrolysate of SPI significantly
reduced adipose tissue weight as compared with casein. Triglyceride content of
liver was significantly lower in the enzymatic hydrolysate of SPI-fed than in
the casein-fed chicks. Secondary, an enzymatic hydrolysate of SPI was fractionated
with ion-exchange choromatography. Using a hydrophobic resin (HP-21) column, two
fractions were obtained. The unadsorbed fraction was rich in hydrophilic amino
acids, whereas the fraction eluted from the column with 50% ethanol was rich in
hydrophobic amino acids. Chicks were fed with an 18% SPI, an enzymatic hydrolysate
of SPI, or its fractions (unadsorbed and ethanol-eluted) for 3 weeks, and the
comparative effects of various soybean proteins on growth performance, adipose
tissue weight, the triglyceride contents of plasma and liver were examined. The
ethanol-eluted fraction significantly reduced adipose tissue weight, whereas significantly
elevated the concentration of plasma triglyceride as compared with SPI. From the
results obtained above, the mechanisms accounting for the body fat-lowering effect
of feeding a soybean protein in chicks were discussed. Soy Protein Research, Japan5 86-91, 2002.
Key words : soy protein isolate, adipose tissue, plasma triglyceride concentration,
liver triglyceride content, fractions of enzymatic hydrolysate of SPI
1School of Life Studies, Sugiyama Jogakuen University, Nagoya, 464-8662 2Graduate School of Agriculture, Kyoto University, Kyoto 606-8502
ABSTRACT
The effects of a long-term feeding of soy protein isolate hydrolysate (SPI-H)
and the amino acid mixture simulating SPI-H (SPI-AA) on the energy expenditure
and expiration of 13CO2 from dietary 13C-glucose
in a type II diabetic mice, KK-Ay strain were investigated. The mice
of 6 wk old were provided free access to a high fat diet (30% of energy from fat)
for the initial 4 wk to induce diabetes. The animals were divided into four groups
and during the subsequent 4 wk each group of animals was fed a diet containing
35% nitrogen source (SPI-H, casein, SPI-H AA, casein AA), 10% sucrose, and 5%
soybean oil on energy intake restricted regimen to 60% of that given during the
preceding high fat diet. For the last 3 days on the restricted dietary regimen,
the animals were housed in the respiratory metabolic chambers. For the middle
24 h of the metabolic measurement, animals in each group fed a diet that sucrose
was replaced by 13C-glucose. Energy expenditure and respiratory quotient
were significantly higher in the mice fed SPI-H and SPI-H AA diet than those fed
casein and casein AA diet. The expiration rate of 13CO2
from 13C-glucose during the period of initial 12 h was higher in the
animals fed the SPI-H diet than those fed the casein diet. The relative weights
of gastrocnemius muscle were significantly higher in mice fed SPI-H diet than
those fed casein diet. It is concluded that the mice on the SPI-H and SPI-H AA
diet can utilize exogenous glucose more readily than those on the casein and casein
AA diet, respectively. Furthermore, SPI-H diet caused higher increment in glucose
utilization than SPI-H AA diet in diabetic obese mice.
Soy Protein Research, Japan 5 92-98, 2002.
Key words :KK-Ay, 13C-glucose, diabetes, soybean, energy
expenditure
Studies on Inhibitory Effect of Soy Isoflavones on Release of Allergy-related Mediators from Rat Peritoneal Exudate Cells
Mikako TAKASUGI1, Kazuko SHIMADA1 and Koji YAMADA2
1Faculty of Human Life Science, Yamaguchi Prefectural University, Yamaguchi 753-8502 2Faculty of Agriculture, Kyushu University, Fukuoka 812-8581
ABSTRACT
Effect of soy isoflavones and their derivative equol on release of allergy-related
mediators from rat peritoneal exudates cells (PEC) were examined.One hundred mM
of soy isoflavones and equol had no effect on histamine release from rat PEC.
Though soy isoflavone glycosides, daizin and genistin did not have effect on leukotriene
B4(LTB4) release from rat PEC, their
aglycon, daizein and genistein inhibit LTB4 release at 100
mM. The inhibitory effect of genistein was greater
than that of daizein. One hundred mM of equol inhibited
LTB4 release completely, and the effect was dose-dependent. Soy Protein Research, Japan 5 99-102,2002.
Key words : soy isoflavone, allergy, histamine, leukotriene B4
Immunoglobulin Production-regulating Activity of Soy Isoflavones and Environmental Estrogens
Koji YAMADA1, Dal-Ho HAN1, Po-Sheng WU1, Shin YASUDA1, Michihiro SUGANO2 and Hirofumi TACHIBANA1
1Faculty of Agriculture, Kyushu University, Fukuoka 812-8581 2Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502
ABSTRACT
We tried the establishment of estrogen-free culture system of mouse spleen lymphocytes
and found that 7-days cultivation of the lymphocytes in phenol red-free DMEM medium
supplemented with 5% charcol-treated fetal bovine serum allowed us to estimate
immunoglobulin production-regulating activity of environmental estrogens. Using
the system, we found that soy isoflavones such as daidzein and genistein suppressed
IgE production of the lymphocytes at low concentrations around 10-8 M,
while enhanced IgE production at high concentrations over 10-4 M. An
endogenous estrogen, 17 b-estradiol exerted only IgE
production-enhancing activity at high concentrations. These results suggest that
IgE production-suppressing and -enhancing activities are regulated by different
mechanisms. Soy Protein Research, Japan5 103-107, 2002.
Key words : mouse splenocytes, isoflavone, immunoglobulin production
Effects of Isoflavone Glucoside and Aglycone on Thrombogenicity as Measured Using apo-/-LDLR-/-Double Knockout Mice
Junichiro YAMAMOTO1, Yoshinobu IJIRI1, 2, Mayu MURAKAMI1, Mayuko MIURA1 , Tsutomu YAMASHITA1, Masaru HASHIMOTO1, Kazuhiro OIWA3 and Toyoko OKUDA4
1Faculty of Nutrition, Kobe Gakuin University, Kobe 651-2180 2Faculty of Health Science, Hyogo University, Kakogawa 675-0101 3Communications Research Laboratory, Kansai Advanced Research Center, Kobe 651-2492 4Department of Art and Sciences, Osaka Kyoiku University, Kashiwara 582-8582
ABSTRACT
Prevention of life style-related diseases, in which thrombogenesis is deeply involved,
is the currently important social problem. Diet is undoubtedly one of the important
risk factors of the diseases. Therefore, prevention of thrombogenesis is beneficial
for that of the diseases. To prevent, prothrombotic state has to be assessed.
Currently used multifactorial tests seem not to have succeeded. As thrombus is
the result of the interaction among blood cells, blood vessels and blood flow,
we established a sensitive and reproducible animal model of thrombogenesis for
assessing the effect of diets on thrombotic state. In the model thrombus is formed
by He-Ne laser irradiation in the carotid arteries of genetically atherogenic
mice deficient both in apolipoprotein E (apoE-/-) and low density lipoprotein
receptor (LDLR-/-). We have demonstrated using this model that genistein-rich
isoflavone aglycone prevents high fat diet-induced prothrombotic states. However,
purity of the isoflavone preparation used in this study was low (30%). Therefore,
the results were not conclusive. The aim of the present study was to clarify the
antithrombotic effect of isoflavone and to compare the effects of isoflavone forms,
glucoside (daidzin and glycitin rich) and aglycone (daidzein and glycitein rich)
, using the preparation with high purity (glucoside 80% ;aglycone 90%). The male
mice were raised with commercial solid diet until 6 weeks of age and the test
diet feeding started from 6 until 14 weeks of age. Isoflavones were supplemented
to the basic high fat diet (40% in energy;ontrol diet) to be 25 mg/kg diet (glucoside),
13 mg/kg diet (aglycone equivalent to 25 mg/kg diet of glucoside in molar concentration)and
650 mg/kg diet (aglycone). Thrombus was formed in the left carotid artery by He-Ne
laser irradiation in the presence of Evans blue. He-Ne laser-induced thrombosis
method (in vivo) revealed that aglycones showed antithrombotic effect at 13 mg/kg
diet (P=0.031) and at 650 mg/kg diet (P=0.007) but not glucoside (P =0.349). Shear-induced
platelet reactivity test (in vitro)showed the antiaggregatory tendency in aglycone
at 650 mg/kg diet (P=0.064). The results confirmed that daidzein and/or glycitein
have antithrombotic effect, but not daidzin and/or glycitin. The antithrombotic
effect may be partly due to antiaggregatory effect. Deficiency of antithrombotic
effect in glucoside might be due to its lower absorption in the intestine. Soy Protein Research, Japan5 108-116, 2002.
Key words : thrombosis, atherosclerosis, isoflavone, polyphenol, platelets
Studies on Bone-protective Function of Isoflavone via the Mevalonate Metabolic Pathway
Hidemichi EBISAWA and Yasuko KOSHIHARA
Bone Research Group, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015
ABSTRACT
The purpose of the present study was to elucidate the mechanism on bone protective
function of isoflavone in relation to mevalonate-geranylgeranylpyrophosphate (GG-PP)
metabolic pathway and signal transduction. We examined the effects of dietary
isoflavone on mevalonate and GG-PP production in ovariectomized (OVX) aged-rats
in experiment-1 and the effects of daidzein and genistein treatment on Rho-A level
in rat osteosarcoma cells (UMR-106) in experiment-2. In experiment-1, rats fed
isoflavone supplemented diet (OVX-IF) showed 1) relatively lower biochemical markers
of bone metabolism, 2) higher urinary mevalonate and relatively higher serum GG-PP
than those of control (OVX-CA). In experiment-2, 3) daidzein or genistein treatment
caused apparently lower Rho-A level in particulate and soluble fraction and lower
ratios of particulate to soluble fraction (P/S ratio) than those of control. 4)
Mevalonate caused higher P/S ratio than that of control, although diminished Rho-A
level was observed. 5) Diminished Rho-A level by genistein treatment was rescued
by co-treatment with mevalonate or GG-PP. These results suggest that daidzein
and genistein inhibits the expression and activation of Rho-A by mevalonate-GG-PP
metabolic pathways in osteoblast. But, in the present study, dietary isoflavone
did not reduce the mevalonate and GG-PP production in rats since aged female rats
had wide variation of responsibility to dietary isoflavone. Soy Protein Research, Japan5 117-121, 2002.
Key words :isoflavone, daidzein, genistein, mevalonate, Rho-A
Preventive Effects of Dietary Isoflavone on Age-associated Modulation of Lipid Metabolism and Antioxidative System in Rats
Kyoichi OSADA, Wakako TSURUGASAKI, Yuki KAWAKAMI and Shingo NAKAMURA
Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki 036-8561
ABSTRACT
Male Sprague-Dawley rats, 4 weeks (immature) or 8 months (mature) of age, were
given one of purified diets with or without 0.15% isoflavone-aglycone (IFA) to
know the regulative effects of dietary isoflavone on modulations of antioxidative
function and lipid metabolism with aging. Dietary IFA inhibited the age-related
lowering of the activities of antioxidative enzymes such as superoxide dismutase,
glutathione peroxidase and catalase in both red blood cells and liver. Moreover,
the increase of levels of lipid hydroperoxides such as phospholipid hydroperoxides
in both serum and liver was lowered by consumption of IFA. Dietary IFA also regulated
the activities of hepatic key enzymes of lipid metabolism including cholesterol
synthesis, cholesterol catabolism and linoleic acid desaturation in both immature
and mature rats. Dietary IFA seems to have potent regulative function against
the modulation of antioxidative system with aging among each regulative function
of dietary components. Oxidative damage and deleterious perturbation of metabolism
in biological systems is one of the triggers of aging process and degenerative
diseases such as atherosclerosis and cancer. Therefore, a part of degenerative
diseases caused by modulations of antioxidative function and lipid metabolism
with aging may be prevented by consumption of IFA. Soy Protein Research, Japan5 122-128, 2002.
Key words : isoflavone, aging, lipid metabolism, antioxidant, rat
1Koshien University College of Nutrition, Takarazuka 665-0006 2Japan Immunoresearch Laboratoies, Takasaki 540-0021
ABSTRACT
For obese subjects who were unable to reduce body weight on the regular dietary
therapy, 300-350 kcal supplementary lunch or alternatively breakfast and 150 kcal
subsidiary dish made of soybean protein added to dinner were advised to take in
a total 1, 200-1, 500 kcal per day. This energy is 200-300 kcal less than the
estimated daily energy expenditure in the regular daily life. After at least 3
months, 3-5 kg weight reduction and 4-8 cm decrease of west size and improvement
of metabolic parameters including triglyceride (TG), cholesterol (chol), Apo-B
and insulin levels have been observed in 44% of the subjects. No reduction of
body weight was noted in 21% because of possible failure to reduce other food
than soybean supplement. In 35%, they could not continue supplementary diet because
of taste and cloying. In successful group, basal level of TG, Apo-B and LDL-chol
as well as 1 h insulin, 2 h chol and Apo-B at 1 and 2 h all reduced after dietary
treatment. By PAGE analyses, elevation of VLDL at 1 h after the test meal significantly
reduced following soybean supplementation. In conclusion, diet treatment using
supplementary food made of soybean protein was effective in half of the subjects
for the efficient weight reduction in the obese subjects who had not responded
to the regular dietary guideline. Soy Protein Research, Japan5 129-133, 2002.
ABSTRACT
The health benefits of soybean isoflavones gather recently much concern. While
soy isoflavone is recognized as phytoestrogen that may affect bone metabolism,
there were few clinical experiments reported. We examined preliminary clinical
trial (Experiment 1) by 5 postmenopausal women who were outpatients of Kato Clinic
in Komae, Japan. Each subject was given detailed informed consent, and agreed
experimental protocol. Bone density, osteocalcin and bone-type alkaline phosphatase
were measured 3 times (at start, 6 months and 1 year) with ingestion of 10 Isofla
tablets/day that contained 10 mg soy isoflavone in total. As a result, bone density
was maintained and osteocalcin and bone-type alkaline phosphatase were increased
significantly. Other blood profiles were not changed but some improvement in motion
was observed. In experiment 2, 20 Chinese outpatients in Beijing, China who were
diagnosed as osteoporosis, and did not take any osteoporosis curative medicine
such as calcareous preparation participated in this experiment. They were divided
into two groups that matched age and gender, then were administered 10 tablets/day,
which contained 2 mg isoflavone / tablet or placebo tablet. After 6-month ingestion,
lumber spinal bone density was increased in Isofla group (initial, 1.011 ±
0.069 ; 6 month, 1.040 ± 0.068 ; change=3.07%), while slightly decreased
in placebo group (initial, 1.074 ± 0.081 ; 6 month, 1.056 ± 0.082
; change=-1.69%), although it had no significance. Plasma Ca and P were not changed
from initial values and only alkaline phosphatase tended to increase in Isofla
group. These data obtained from just 6 months to 1-year ingestion suggested that
soy isoflavone might improve bone maintenance. To confirm these data, long-term
follow-up is necessary. Soy Protein Research, Japan5 134-137, 2002.
Key words : soy isoflavone, phytoestrogen, bone metabolism, bone density
1Kyoto University Graduate School of Human and Environmental Studies, Kyoto 606-8501 2Research Institute for Promotion Development, Kyoto 606-8501 3WHO Collaborating Center for Primary Prevention of Cardiovascular Diseases, Kyoto 606-8501
ABSTRACT
Although Japanese have the longest life expectancy at birth in the world, numbers
of dementia (vascular type, Alzheimer type) and bedridden disability are increasing
due to the rapid increase in elderly population. There are accumulating evidence
that soy protein as well as isoflavones reduce risk factors for cardiovascular
diseases in relation to lowering blood pressure (BP) and total cholesterol (T-CHO)
levels. However, it is not yet tested in a double blind design that soybean diets
do reduce cardiovascular risk factors especially in elderly female population.
In this study, we investigated whether soy-protein-fortified diets reduce cardiovascular
risk factors in Japanese elderly women by means of double blind trial. Our results
revealed that urinary isoflavone excretion in 24-hour urine collection was significantly
increased in soy-protein-fortified group (P < 0.01). We also observed significant
reduction in T-CHO, LDL-CHO and systolic blood pressure (SBP) in soy-protein-fortified
group whereas placebo group did not show significant difference in a 4-week period.
Our study suggests that dietary intake of soy protein over 25 g/day containing
over 50 mg of isoflavones per day could prevent cardiovascular diseases by reducing
BP, T-CHO and LDL cholesterol levels even in postmenopausal elderly women. Also
soy-protein-fortified products have potential benefits for the primary prevention
for cardiovascular as well as lifestyle-related diseases through improving eating
habits. Soy Protein Research, Japan5 138-143, 2002.