The Molecular Mechanism of Improved Lipid Metabolism by β-conglycinin Based on Novel Active Peptide Identification
Satoshi NAGAOKA*1, Toshiro MATSUI2 and Hiroyasu ITO3
1Faculty of Applied Biological Sciences, Gifu University, Gifu 501-1193
2Faculty of Agriculture, Graduate School of Kyushu University, Fukuoka 812-8581
3Departments of Informative Clinical Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194
ABSTRACT
It is well known that β-conglycinin is a major soybean protein component that lowers lipid levels in animals and humans. However,
there is no information about the active amino acid sequence involved in lipid reduction by β-conglycinin in vivo . We identified,
for the first time, that blood plasma contains some β-conglycinin- derived peptides (348.1813 m/z, 460.2497 m/z, 515.2302 m/z,
553.2532 m/z) by MALDI-MS and LC-TOF/MS after orally administering β-conglycinin in rats once. We also identified,
for the first time, that the portal blood plasma contains some β-conglycinin-derived peptides (302.196 m/z, 308.185 m/z)
after orally administering β-conglycinin in rats once by TOF-MS and LC-TOF-MS. We found, for the first time, that peptide X,
a novel β-conglycinin-derived peptide, was responsible for lipid reduction in rats.
Soy Protein Research, Japan 22, 1-4, 2019.
Key words : peptide, beta-conglycinin, plasma peptide
Anti-inflammatory Effect of Water-soluble Soy Isoflavones on Murine Gut Microbiome and Aging
Sang Eun KIM1, Yuka KAMEI1, Ikuo KIMURA2 and Mitsuo MARUYAMA*1,3
1Department of Mechanism of Aging, National Center for Geriatrics and Gerontology (NCGG), Aichi 474-8511
2Department of Applied Biological Science, Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8538
3Department of Aging Research, Nagoya University Graduate School of Medicine, Nagoya 466-8550
ABSTRACT
With the advent of an unprecedented aging society, the proportion of elderly patients with inflammatory bowel disease (IBD) has gradually
increased. On the contrary, several biomedical studies including ours have revealed that nutritional interventions such as soy isoflavone
have anti-inflammatory and antioxidant effects on various animals and cells, including IBD model mice. Here we focus on the water-soluble
soy isoflavones (Soyaflavone HG; SHG; Fuji Oil Co., Ltd), which contains glycoside forms of isoflavones and has beneficial effects such as
anti-inflammatory and anti-oxidant properties, and study its potential effect on aging by nutrition intervention. In this study,
we investigated the effect of SHG on the intestinal flora and alteration of gut microbiota with 16S rRNA next generation sequencing.
Specifically, we sequenced the 16S rRNA of fresh fecal samples from two-month old male C57BL/6N mice with free access to drinking
water containing 0.5% SHG for four weeks. Consequently, according to Beta diversity analysis based on principal coordinate analysis (PCoA),
we confirm that the gut microbiota in fecal samples after SHG treatment for two and four weeks clearly differ from that in control
samples (sample collected before SHG treatment). These results indicate that the beneficial effects of SHG on maintaining the intestinal
environment and homeostasis are closely related to changes in the intestinal microflora.
Soy Protein Research, Japan 22, 5-14, 2019.
Key words : soy isoflavones, murine intestine, microbiome, short chain fatty acids (SCFAs), inflammation
Controlling Hepatitis C Virus and Drug-resistant Viruses by Isoflavones
Koichi WATASHI*
Department of Virology II, National Institute of Infectious Diseases, Tokyo 162-8640
ABSTRACT
Hepatitis C virus (HCV) modifies host cellular function to accumulate hepatic lipid droplets,
which induces efficient production of progeny viruses and elevated risk for developing tumor.
In this study, from a chemical screening using HCV production cell culture system,
we identified isoflavones that impaired the cellular ability to produce infectious HCV.
These isoflavones, #89, #98, and #101, reduced HCV production dose-dependently without exerting cytotoxicity.
#98, which reduced HCV production to less than 25%, reduced hepatic lipid droplets, which serve as a platform for viral assembly.
This compound was revealed to repress aryl hydrocarbon receptor (AhR) and block the induction of its downstream gene,
cytochrome P450 1A1 (CYP1A1) to reduce viral assembly. Moreover, it was shown that an inhibitor of the AhR-CYP1A1 pathway
effectively reduced the production of a drug-resistant HCV. Thus, we identified isoflavones that reduced hepatic lipid droplets and
HCV production. These data provide evidence for the possible utility of isoflavones to control HCV-related diseases as well as
analyze the mechanisms underlying HCV-induced cellular reorganization.
Soy Protein Research, Japan 22, 15- 20, 2019.
Key words : isoflavone, hepatitis, virus, aryl hydrocarbon receptor, cytochrome P450, CYP1A1
Development of Soy Protein-derived Antimicrobial Peptides to Prevent Post-harvest Disease in Citrus Fruits
Takashi YAENO*
Faculty of Agriculture, Ehime University, Matsuyama 790-8566
ABSTRACT
β-conglycinin has antimicrobial activity against a postharvest fungus in citrus fruits. Therefore,
to identify the minimum peptide region required for antimicrobial activity, three,
three, two peptide regions were selected from α´, α, and β subunits, respectively,
by machine learning. The peptide fragments were synthesized using Pichia protein expression system to
examine their antimicrobial activity. As a result, α´ peptide regions were selected as candidates with the activity.
Soy Protein Research, Japan 22, 21-23, 2019.
Key words : citrus, Penicillium digitatum, antimicrobial peptide, machine learning, Pichia pastris
Genetic Analysis of High Vitamin E Content from Wild Soybean
Maria Stefanie DWIYANTI*1, Cheolwoo PARK2, Atsushi NAGANO3, Tetsuya YAMADA1 and Jun ABE1
1Research Faculty of Agriculture, Hokkaido University, Sapporo 060-8589
2Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589
3Department of Plant Life Sciences, Faculty of Agriculture, Ryukoku University, Shiga 520-2194
ABSTRACT
Tocopherols are lipophilic antioxidants that belong to the vitamin E group.
There are four isoforms of tocopherols (α-, β-, γ-, and δ-Toc). Among these,
α-Toc has the highest vitamin E activity. It is also reported to be able to prevent aging related diseases such as
cancer and cardiovascular diseases. Based on soybean and wild soybean germplasm screening, several accessions have a
high α-Toc ratio. In this study, we investigated the α-Toc ratio distribution in F2 progenies from
the cross between high α-Toc soybean ‘KAS’ and high α-Toc wild soybean ‘B04009’ and those from
the cross between ‘KAS’ and high α-Toc wild soybean ‘B08040’. There were several F2 progenies having a α-Toc ratio higher
than that of ‘KAS’. Using Rad-seq genotyping method on low and high α-Toc accessions, we determined the genomic
regions correlating with increased α-Toc ratio in ‘KAS’בB04009’ and ‘KAS’בB08040’ F2 population.
Soy Protein Research, Japan 22, 24-28, 2019.
Key words : vitamin E, soybean, nutraceutical, genotyping-by-sequencing
Inactivation of Lipoxygenase in Soybean Seeds Mediated by Genome Editing Technology
Tetsuya YAMADA*1 and Yuto FURUKAWA2
Graduate School of Agriculture, Hokkaido University, Sapporo 060-8589
ABSTRACT
Genome edited plants for the lipoxygenase-3 gene (LOX-3), which is mainly activated in soybean seed tissue,
were generated using the CRISPR/Cas9 system. Most T2 seeds were found to possess mutations in the LOX-3 targeted region by the CAPS analysis.
In addition, the sequence analysis of these seeds revealed that 1–21 nucleotides were deleted in the LOX-3 targeted region.
Some mutant T2 seeds were null-segregates in which the transgenes were removed through genetic segregation.
The chemical assay for LOX-3 activity showed that the activity was extremely reduced in all mutant T3 seeds.
To confirm the relationship between LOX-3 activity and n-hexanal production, soymilk samples were prepared from
representative mutant T3 seeds. The GC-MS analysis of n-hexanal revealed that the n-hexanal production in the sample from
mutant seeds was decreased to about 20% of that in the sample from wild-type seeds.
These results suggest that LOX-3 activity is strongly involved in n-hexanal biosynthesis.
Furthermore, the relationship between LOX-3 activity and seed viability was also confirmed.
Exposing mutant T3 seeds temporarily to high temperature and high humidity conditions was regarded as the aging treatment.
The germination test implied that the aging treatment caused more serious damage to viability in
wild-type seeds than in mutant T3 seeds. This result suggests that the decrease of LOX activity in
seeds might lead to the modification of viability in soybean seeds.
Soy Protein Research, Japan 22, 29-34, 2019.
Key words : Glycine max, genome editing, CRISPR/Cas9, lipoxygenase, n-hexanal
Development of ‘Food Ink’ from Soy Protein Isolate for 3D Food Printing
Makoto TAKEMASA*
Tokyo Denki University, Graduate School of Science and Engineering, Life Sciences and Engineering, Saitama 350-0394
ABSTRACT
Soy protein isolate (SPI) was used to develop edible paste ink as ‘Food Ink’ for food 3D printing.
Aqueous solutions of soybean protein were prepared at various concentrations ranging from 5 to 50%.
In all the concentrations, extrusion from the syringe was possible,
but the quality of the printed object was relatively low compared with the other food inks,
probably due to the viscoelastic properties of aqueous suspensions of SPI alone. Xanthan,
a microbial polysaccharide used in food industry as a thickener, was added to improve the viscoelastic properties to
maintain the object shape. The food ink developed in this study was relatively more precise than other food inks.
Soy Protein Research, Japan 22, 35-39, 2019.
Key words : food 3d printing, soy protein isolate (SPI), xanthan, viscoelasticity, thickener
Real-time Nanostructural Analysis of Soy Protein Gelation by Small-angle Quantum Beam Scattering
Nobuhiro SATO*, Reiko URADE and Masaaki SUGIYAMA
Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka 590-0494
ABSTRACT
Nanostructural change of two major soy proteins, β-conglycinin (7S) and glycinin (11S),
that accompanies their thermal denaturation by preheating and coagulation by adding glucono-δ-lactone (GDL) was investigated by
small-angle X-ray scattering (SAXS) under various solvent conditions with or without potassium phosphate (KPi) buffer and NaCl.
For solutions in KPi, a peak is recognized at 1.2 nm-1 scattering vector,
indicating the formation of characteristic structure associated with 7S and 11S subunit trimers.
However, this peak is not found in 0.5% 7S and 11S solutions in water, suggesting that
the trimeric subunit structure cannot be maintained due to the dissociation of the subunits.
When NaCl is added to the KPi buffer solutions of 7S, the shoulder of the scattering curves at
0.5 nm-1 shifts to higher q position with increasing NaCl concentration, which is in agreement with the fact that
hexameric subunit structure forms by stacking two subunit trimers in low ionic strength solutions and
the subunit hexamers separates into two subunit trimers. Thermal stability of the trimeric 7S and
11S subunit structure of in 3% solutions is higher in KPi buffer solutions than in water solutions and
NaCl presence promotes this effect. Preheating and adding GDL to water solutions of 3% 11S at
70°C causes rapid structural change in 3 min due to thermal denaturation and coagulation, whereas no changes occur at 25°C.
Soy Protein Research, Japan 22, 40-44, 2019.
Key words : SAXS, β-conglycinin, glycinin, thermal denaturation, coagulation
Development of Novel Functional Food with Atomized Soybean Residue
Takao NAGANO*
Department of Food Science, Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Ishikawa 921-8836
ABSTRACT
It is necessary to improve the physicochemical properties of okara, soybean residue,
for various applications in food. Okara and microcrystalline cellulose (MCC) were atomized using Star Burst (SB) system.
The SB-treated okara and MCC dispersed homogeneously in water.
The particle size distribution (PSD) was determined to be using a laser scattering PSD analyzer,
indicating that the median sizes of SB-treated okara and MCC were 6.6 and 9.5 μm, respectively.
The dispersions of SB-treated okara and MCC showed high apparent viscosity at low shear rates and their apparent viscosity
decreased with increasing shear rates, indicating shear thinning behavior. In addition,
α-amylase activity inhibition after 90 min was 50±5%, 41±3%, and 20±1% for SB-treated okara, MCC, and cellulose, respectively.
Inhibition of α-amylase activities of SB-treated okara and MCC were significantly greater than that of cellulose.
Furthermore, acetate, propionate, and butyrate production by 32 dominant human gut microbial species were determined in the presence and
absence of 0.5% SB-treated okara. The amount of acetate was significantly higher in the presence of
SB-treated okara for Bacteroides caccae. The amount of butyrate was significantly higher in the presence of
SB-treated okara for Roseburia intestinalis and Coprococcus comes. Moreover, the increase in butyrate production by
Roseburia intestinalis was observed in the presence of SB-treated okara but not in the presence of untreated okara and
SB-treated MCC. These results suggest that SB system is a useful machinery for okara to develop anti-obesity foods.
Soy Protein Research, Japan 22, 45-49, 2019.
Key words : okara, dispersion performance, viscosity, α-amylase inhibition, Roseburia intestinalis
Effects of Daidzein or its Metabolites on Skeletal Muscle Mass
Rina SASAKI, Natsuha KAWATA and Ryoichi YAMAJI*
Laboratory of Nutrition Chemistry, Division of Applied Life Sciences, Graduates School of Life and Environmental Sciences, Osaka Prefecture University, Osaka 599-8531
ABSTRACT
Skeletal muscle is composed of myofibers, accounting for approximately 40% of human body weight.
Skeletal muscle mass depends on net protein content, which is regulated by a balance between protein synthesis and degradation.
The aim of this study was to assess whether the soy isoflavone daidzein contributes to protein synthesis.
Daidzein increased myotube diameter, promoted protein synthesis, and activated 4E-BP1 phosphorylation,
which is the downstream substrate of mTOR signaling, in C2C12 myotubes. Dietary daidzein increased
the soleus muscle mass to body weight ratio in female, but not in male,
C57BL/6J mice and activated 4E-BP1 phosphorylation in the soleus muscle of female mice. In daidzein-fed mice,
daidzein and its metabolite, S-equol, were detected in plasma.
S-equol induced hypertrophy and promoted protein synthesis in C2C12 myotubes. Furthermore,
it activated the phosphorylation of mTOR and its downstream substrate, p70S6K, in C2C12 myotubes.
When female mice were fed a diet containing daidzein and kanamycin, daidzein was detected in plasma,
but not S-equol. The concomitant administration of daidzein and kanamycin suppressed daidzein-induced increase in the soleus
muscle mass to body weight ratio in female mice. These results indicate that daidzein and
S-equol activated mTOR signaling in C2C12 myotubes and suggest that S-equol, rather than daidzein,
contributes to soleus muscle mass increase due to daidzein intake in female mice.
Soy Protein Research, Japan 22, 50-55, 2019.
Key words : isoflavone, daidzein, S-equol, skeletal muscle, kanamycin, mTOR signaling
Development of Preparation Methods of Equol Conjugates for Elucidating the Physiological Role of Equol Metabolites
Shinichi IKUSHIRO*
Department of Biotechnology, Faculty of Engineering, Toyama Prefectural University, Toyama 939-0398
ABSTRACT
Dietary compounds such as polyphenols of vegetables or fruits are conjugated with xenobiotic phase II enzymes,
UDP-glucuronosyltransferases (UGT) and sulfotransferase (SULT) isoforms, and
their biological effects partially depend on the formation of the conjugates.
We have developed several mammalian UGT or SULT expression systems to biosynthesize the conjugates as dietary metabolites in
budding yeast. In order to elucidate the metabolism and pharmacokinetics of equol metabolites,
glucuronides or sulfates were analyzed and prepared using UGT- or SULT-isoform expressing budding yeast.
Using human hepatic or intestinal microsomes, R- and S-equol were preferentially glucuronidated
at position 7 of the hydroxyl group (E-7G) in human and mouse. In contrast, 4´-equol glucuronide (E-4´ G) was mainly produced by rat.
Equol metabolism in UGT-isoform expressing yeast showed rat UGT2B1 and human UGT1A9 to be capable of producing E-4´ G and E-7G,
respectively. Mouse Ugt2b1, an ortholog of human UGT2B7, catalyzed E-7G production.
Human SULT isoforms (SULT1A1, 1A3, 1E1, 2A1) catalyzed the sulfation of R- and S-equol at position 7 of the hydroxyl group (E-7S).
Selecting the suitable mammalian UGT isoforms in yeast, we can get the desirable glucuronides of R- and S-equol.
These mammalian UGT or SULT expression systems in budding yeast would be a powerful tool for enzyme-assisted synthesis of
equol metabolites including glucuronides and sulfates.
Soy Protein Research, Japan 22, 56-60, 2019.
Key words : equol, glucuronide, sulfate, UDP-glucuronosyltransferase, sulfotransferase
Characterization of Brain Sensing Mechanism of Astringency and Harsh Taste Derived from Soy Beans
Ken-ichiro NAKAJIMA*
National Institutes of Natural Sciences, National Institute for Physiological Sciences, Division of Endocrinology and Metabolism, Aichi 444-8585
ABSTRACT
While many studies indicate the beneficial effects of soy phytochemicals on health,
some consumers refuse soy foods due to their unique sensory characteristics such as astringency and harsh taste.
Although understanding the sensing mechanism of five basic tastes (sweet, umami, bitter, sour, salty) has been extensively progressed in
recent years, the astringency and harsh taste transduction mechanism in the brain still remains unclear. To address this issue,
here we examined whether gustatory neurons in the mouse brainstem can respond to astringency and/or harsh taste using
the fiber photometry based in vivo calcium imaging analysis.
We introduced recombinant adeno-associated virus encoding GCaMP6 fluorescence calcium indicator into
the brainstem for imaging neuronal activities during taste licking behaviors.
While the neuronal responses were not detected when the mice licked pure water,
large responses were observed when they tasted bitter or sour solution. Importantly,
such responses were also observed when the same mice licked daidzin or saponin solution,
both of which are rich in soybeans and exhibit astringency and harsh taste.
These results suggest that parts of gustatory neurons in the mouse brainstem can respond to astringency and harsh taste.
Further analysis would allow us to identify the key neurons responsible for astringency and harsh taste transduction in the mouse brain.
Soy Protein Research, Japan 22, 61-63, 2019.
Key words : astringency, harsh taste, brainstem, in vivo calcium imaging
Analysis of Tissue Distribution of Soy Isoflavone by Mass Spectrometry Imaging
Hirofumi TACHIBANA* and Yoshinori FUJIMURA
Division of Applied Biological Chemistry, Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, Fukuoka 819-0395
ABSTRACT
The spatial distribution of bioactive soy isoflavones is an indispensable information for elucidating their biological effects.
However, there has been no analytical technique that can easily detect the localization in mammalian tissues. Therefore,
in this study we present a novel in situ label-free imaging technique for visualizing the localization of daidzein,
one of the major isoflavones, within mammalian tissue after oral administration
by establishing a matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) technique.
To effectively ionize the daidzein for MALDI-MS, the optimum matrix needs to be determined. For screening the daidzein candidate matrix,
mixtures of daidzein and each chemical compound solution were directly spotted onto a stainless MALDI sample plate and
measured by using MALDI-MS. Among the nine chemicals selected as the potential matrix,
1,5-diaminonaphthalene (1,5-DAN) could effectively ionize daidzein (m/z 253 [M-H]¯) on MALDI sample plate in negative ionization mode.
By using 1,5-DAN-based MALDI-MS, daidzein was not visualized within the liver and kidney sections of daidzein-administered mouse,
but its sulfated form was observed in the kidney section. These results suggested that MALDI-MSI could visualize sulfated conjugation of
daidzein after oral administration in mammalian tissues without any labeling.
Soy Protein Research, Japan 22, 64-67, 2019.
Key words : isoflavone, daidzein, mass spectrometry imaging, MALDI-MS, localization
Protein Modifications with Antioxidative Dihydroxyisoflavones and Their Effects on Innate Immune Responses
Eita SASAKI*
Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657
ABSTRACT
Food-derived antioxidants are believed to reduce oxidative damage caused by reactive oxygen species, thus being beneficial for human health.
Here, protein modifications with o-dihydroxyisoflavones, strong antioxidants found in fermented soy products,
and their potential effects on innate immune responses are examined. Four commercially available isoflavones, daidzein, genistein,
6-hydroxydaidzein (6-OHD), and 8-hydroxydaidzein (8-OHD), were incubated with human serum albumin (HSA) in phosphate buffered saline at
37°C overnight. Gel filtration of the protein followed by spectrophotometric analyses indicated that
8-OHD formed a complex with HSA although no evidence of protein modification was found with the other three isoflavones examined.
To evaluate the immunoreactivity of mice sera with the isoflavone-modified HSA,
enzyme-linked immunosorbent assay (ELISA) was performed against the protein.
The titers of both IgM and IgG in the BALB/c mouse sera against 8-OHD-HSA were found to be higher than
those against unmodified HSA or HSA treated with the other isoflavones. In addition,
the phage- displayed single-chain variable fragment (scFV) library constructed from a BALB/c mouse spleen was used for phage ELISA with
the isoflavone-modified HSA. The titer of scFV antibody fragments against 8-OHD-HSA was significantly increased after two rounds of
biopanning, an affinity-based selection, with 8-OHD-HSA. These results suggest that 8-OHD, which exhibits strong antioxidative activity,
readily modify serum proteins upon oxidation. Since the 8-OHD-modified HSA was shown to be recognized by
natural antibodies in the mouse sera, the oxidized 8-OHD has a potential to modulate the innate immune responses.
Soy Protein Research, Japan 22, 68-72, 2019.
Key words : antioxidant, isoflavone, 8-hydroxydaidzein, natural antibody, innate immunity
Reactive Sulfur Species in Soy Protein
Hideshi IHARA*
Department of Biological Science, Graduate School of Science, Osaka Prefecture University, Osaka 599-8531
ABSTRACT
Reactive sulfur species (RSS), such as cysteine hydropersulfide (CysSSH), have sulfane sulfur atoms bound to thiol.
RSS are involved in various pathophysiological functions owing to their strong antioxidative and regulatory activities for redox signaling.
The RSS level increase in the body is expected to prevent, and also treat, various diseases because of oxidative stress.
However, few studies have focused on RSS in food, which is the source of RSS in body to date.
This study aimed to evaluate RSS in soy protein.
A quantitative analysis method using HPLC–electrospray ionization–tandem MS (HPLC-ESI-MS/MS) was established.
Soy protein was reduced by dithiothreitol to release RSS-derived sulfurs.
The released sulfurs were captured by N-ethylmaleimide and were quantitatively analyzed using HPLC-ESI-MS/MS coupled with
stable isotope dilution methods. Using this method, RSS were detected in soy protein.
To increase the RSS level, solubilized soy protein was treated with RSS donors, such as sodium tetrasulfide. After the treatment,
the RSS level in soy protein markedly increased than that it the untreated soy protein.
RSS donor-treated soy protein was fractionated by anion-exchange chromatography,
and the RSS level in each fraction was analyzed; RSS were mostly detected in non- adsorption fraction.
Mass spectrometry analysis revealed that the major component of the non-adsorption fraction was the basic subunit of glycinin.
Our results suggest that RSS is selectively incorporated into the basic subunit of glycinin.
Soy Protein Research, Japan 22, 73-77, 2019
Key words : reactive sulfur species, soy protein, HPLC-ESI-MS/MS
Transporter Engineering Focused on the Oligopeptide Uptake in Saccharomyces cerevisiae to Increase Flavoring Agent Production
Keisuke ITO*
Department of Food and Nutritional Sciences, University of Shizuoka, Shizuoka 422-8526
ABSTRACT
Peptide uptake systems with proton-coupled oligopeptide transporter (POT) are conserved across all organisms.
POT proteins have characteristic substrate multispecificity,
by which one transporter can recognize as many as 8,400 types of di/tripeptides.
The substrate multispecificity of POT family may enable efficient nitrogen source uptake into the cells. Therefore,
improved POT activity is expected to promote cell growth and increase the production of useful substances made from amino acids.
In this study, we investigated the effects of improving POT activity for flavoring agent production using Saccharomyces cerevisiae.
As a result of screening for eukaryotic POTs,
Candida albicans PTR2 (caPTR2) showed a significantly higher substrate affinity than other POTs.
The comprehensive analysis of the affinity of 338 dipeptides revealed that caPTR2 is an ultra-high-affinity POT
because the average Ki value of caPTR2 was about 1/100 of that of human PEPT2 (hPEPT2), which is a high-affinity type POT.
caPTR2 expressing-yeast showed an excellent growth rate in soy peptide-based medium and an increase in the production of glutathione,
Kokumi peptide, and β-phenylethyl alcohol, aromatic alcohol with a rose-like fragrance, compared with those in the S.
cerevisiae Ptr2p expressing-yeast. Thus, transporter engineering focusing on the oligopeptide uptake in S.
cerevisiae is one of the effective strategies to increase flavoring agent production during fermentation.
Soy Protein Research, Japan 22, 78-82, 2019.
Key words : oligopeptides, peptide transporter, Saccharomyces cerevisiae, flavor substances
Host-defense Activities and Mechanism of Actions of Cationic Peptides from Soybean Protein Hydrolysates
Masayuki TANIGUCHI*
Department of Materials Science and Technology, Niigata University, Niigata 950-2181
ABSTRACT
In this study,
we used soybean protein hydrolysates as crude peptide samples and generated 20 fractions containing multifunctional cationic peptides with
varying isoelectric point (pI) values using ampholyte-free isoelectric focusing (autofocusing).
Subsequently, we determined the antimicrobial activities of each fraction against Prophyromonas gingivalis,
Propionibacterium acnes, Streptococcus mutans, and Candida albicans.
Fractions 19 and 20 had pI values greater than 10 and exhibited antimicrobial activity against Prophyromonas gingivalis,
Propionibacterium acnes, and C. albicans, but not against S. mutans. In further experiments,
we purified and identified cationic peptides from fractions 19 and 20 using reversed-phase high-performance liquid chromatography and
matrix-assisted laser/desorption ionization-time-of-flight mass spectroscopy.
We also chemically synthesized 14 identified peptides with pI values greater than 9.9 and evaluated their antimicrobial,
lipopolysaccharide (LPS)-neutralizing, and angiogenic activities. Among these synthetic peptides,
several peptides exhibited antimicrobial activity against the pathogenic micro-organisms.
In addition, all 14 cationic peptides exhibited LPS- neutralizing activities and
induced angiogenesis of endothelial cells with little or no hemolytic activity
against mammalian red blood cells at functional concentrations. These data show multiple functions of
the 14 identified cationic peptides with little or no hemolytic activity.
Therefore, fractions containing cationic peptides from soybean protein hydrolysates can be potentially used as
dietary supplements and functional ingredients in food products.
Soy Protein Research, Japan 22, 83-90, 2019.
Key words : cationic peptide, soybean protein, antimicrobial activity, LPS-neutralizing activity, angiogenic activity
Cuprizone-induced Demyelination in the Mouse Hippocampus is Alleviated by Phytoestrogen Genistein
Tomohiro OHGOMORI and Shozo JINNO*
Department of Anatomy and Neuroscience, Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582
ABSTRACT
Recent studies have reported that individuals with mental health issues, such as schizophrenia and multiple sclerosis,
often exhibit the pathology of myelin in the central nervous system. In this study,
we aimed to elucidate the validity of phytoestrogen genistein (GEN) for treating myelin impairment using the cuprizone (CPZ)
model of multiple sclerosis. We found that 5-week intoxication of 0.2% CPZ reduced the immunoreactivity for myelin basic protein (MBP),
a major myelin constituent produced by oligodendrocytes, in the corpus callosum of the mouse brain.
CPZ intoxication also reduced the immunoreactivity for MBP in the hippocampus,
and GEN administration inhibited this pathological change. The densities of mature oligodendrocytes
in the hippocampus were decreased following CPZ intoxication, which were counteracted by GEN administration.
Neither CPZ intoxication nor GEN administration affected the densities of oligodendrocyte precursor cells and astrocytes in the hippocampus.
The colocalization ratios of molecular markers for microglia and myelin were increased by CPZ intoxication but
decreased by GEN administration. The expression levels of myelin-related genes,
such as MBP and myelin oligodendrocyte glycoprotein (MOG), in the whole hippocampal tissue were downregulated
by CPZ intoxication but upregulated by GEN administration.
These results show that GEN administration may act on mature oligodendrocytes in the hippocampus
by promoting their survival and myelin formation,
and suggest the therapeutic potential of phytoestrogens for treating patients suffering
from mental health issues related to myelin impairment.
Soy Protein Research, Japan 22, 91-97, 2019.
Key words : cuprizone, genistein, demyelination, hippocampus, oligodendrocyte
Effects of Dietary Soy and Whey Proteins on Muscle Strength Recovery Following Eccentric Contractions
Keita KANZAKI*, Kanako HARA and Yuki YAMASAKI
Faculty of Health Science and Technology, Department of Clinical Nutrition, Kawasaki University of Medical Welfare, Okayama 701-0193
ABSTRACT
This study aimed to determine the effect of soy or whey protein ingestion on force deficit, protein degradation,
and synthesis in rat fast-twitch muscles subjected to eccentric contractions (ECC).
Male Wistar rats were fed a 20% protein diet containing either soy protein isolate (SPI),
whey protein isolate (WPI), soy protein hydrolysate (SPH), or whey protein hydrolysate (WPH) for 4 weeks. Then,
their left anterior crural muscles were exposed to 200-repeated ECC and excised 3 days later. In the WPI and SPH groups,
force production in the extensor digitorum longus muscles was recovered, although the force was still reduced in the SPI and WPH groups.
In the WPH group, ECC-induced dihydropyridine receptor proteolysis and decreased 4E-BP-1 phosphorylation was also observed.
These results suggest that both soy and whey proteins were effective in promoting the recovery of muscle function after ECC treatment.
However, in each protein group, the form of protein (i.e. protein or peptide) may be an important factor contributing to this effect.
Soy Protein Research, Japan 22, 98-102, 2019.
Key words : soy protein, whey protein, soy peptide, whey peptide, skeletal muscle
Studies on Ghrelin Signal Regulation by Soy-derived Peptide for Anti-aging
Kousaku OHINATA*
Graduate School of Agriculture, Kyoto University, Kyoto 611-0011
ABSTRACT
Soybean, a food familiar to Japanese people, might be a food candidate that supports health and longevity;
however, the molecular mechanism in detail is unclear. Ghrelin, an endogenous peptide hormone isolated from the stomach in 1999,
stimulates food intake and growth hormone secretion.
Recently it has been discovered that ghrelin signal enhancement extends the lifespan of aging models.
In this study, we found that enzymatic β-conglycinin digest, known as a major soybean protein,
potentiated calcium signal induced by ghrelin application.
Next, we tried to identify the peptide candidate that contributes to potentiate the ghrelin signal.
The digest was divided into eighty peaks. Among the eighty peaks, six peaks stimulated calcium signaling induced by ghrelin application.
Finally, three candidates were identified from them. We also found that a peptide might stimulate calcium signaling induced by ghrelin.
Soy Protein Research, Japan 22, 22, 103-106, 2019.
Key words : β-conglycinin, peptide, ghrelin, growth hormone secretagogue receptor, anti-aging
Analysis of Anti-cancer Mechanism of the Soybean-derived Protein, lunasin
Koji NAGATA
Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo 113-8657
ABSTRACT
Lunasin is a 44-aa small subunit of a 2S albumin soy storage protein.
Researchers have paid much attention to lunasin recently because of its anticancer effect in vitro and in vivo.
The anticancer mechanism of lunasin has been proposed as follows.
Lunasin molecule migrates through the cell membrane from the environment to the cytosol,
and then through the nuclear membrane from the cytosol to the nucleus. In the nucleus,
lunasin inhibits H3 and H4 histone tail acetylation, which suppresses the expression of various cancerous genes,
inhibits cell division, and finally induces apoptosis.
This study aimed to verify this hypothesis and obtain further understanding on the anticancer mechanism of lunasin.
Our results indicated that (1) the 9×Asp-Asn segment in the C-terminus of lunasin is important,
while the two Cys residues are not important for the anti-cancer activity of lunasin,
(2) both N- and C-terminals of lunasin can enter the cell and the nucleus as well as the full- length lunasin
while the 9×Asp-Asn segment cannot enter efficiently,
and (3) lunasin does not show remarkable intermolecular interaction with histone H3/H4 or nucleosome,
suggesting that it may act as an anticancer agent by a mechanism different from the previously proposed mechanism.
Soy Protein Research, Japan 22, 107-111, 2019.
Key words : lunasin, anti-cancer activity, fragment peptide, soy protein, cell penetrating peptide
Identification of Soy Protein Candidates Involved in the Derivation of Anti-cancer Peptide, Lunasin, from 2S albumin.
Yuho OIZUMI, Ichiko HIRAKAKIUCHI, Koji MURAMOTO, Yoshikazu TANAKA and Tomohisa OGAWA*
Department of Molecular Life Sciences, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577
ABSTRACT
The soybean peptide, lunasin, is known to have anti-cancer and anti-inflammatory effects.
Although lunasin has been reported to be present in various soybean- products, it is hardly found in raw soybean. Previously,
we found the abundant inclusion of lunasin in the soybean-products such as low-fat soymilk and
its formation from 2S albumin under processing conditions with heat treatment at 90°C. However,
lunasin could not be identified in isolated 2S albumin by the same treatment. These results indicated that
some mechanism that exists in soybean. In this study, we analyzed the mechanism of lunasin conversion from
2S albumin under processing conditions. First, it was found that enzymes including protein disulfide isomerase and
purothionin (thioredoxin-like enzyme) did not participate in the cleavage.
Next, to identify the S-S exchange reactive intermediates, we analyzed biotin-labeled 2S albumin by 2D-SDS-PAGE.
As a result, some intermediates linked to the L-chain of 2S albumin were detected at 24, 26, 36.6, 46, 51, and >80 kDa bands.
These results suggest that some soy proteins contribute to the derivation of lunasin from 2S albumin by S-S exchange reaction.
Soy Protein Research, Japan 22, 112-117, 2019.
Key words : 2S albumin, lunasin, processed foods, soybean peptide, S-S exchange
Effects of Equol on Metabolic Syndrome
Atsushi TAKAHASHI*1, Nobuo TANJI2, Yukio ANZAI2, Masashi FUJITA1, Manabu HAYASHI1, Kazumichi ABE1 and Hiromasa OHIRA1
1Department of Gastroenterology and Rheumatology, Fukushima Medical School of Medicine, Fukushima 960-1295
2Department of Gastroenterology, Watari Hospital, Fukushima 960-8141
ABSTRACT
Equol, a soy isoflavone metabolite, has favorable effects on glycolipid metabolism.
Equol production is regulated by intestinal flora and not all people produce it.
This study aimed to elucidate the effects of equol on metabolic syndrome or
its diagnostic components such as visceral obesity, hypertension, dyslipidemia, and hyperglycemia.
This cross-sectional study included 1,086 subjects (315 men, 771 women)
who underwent a health checkup at Watari Hospital (Fukushima) between February and December, 2018.
The two groups (equol producers and non-producers) were compared using the χ2 test and Mann-Whitney U-test for
continuous variables. Among the 1,086 subjects, 338 (31.1%) were equol producers (men, 35.2%; women, 29.4%).
Equol producers were significantly older than the non- producers (mean age, 70 and 67 years, respectively; p = 0.003).
Equol production status had no effect on metabolic syndrome or its diagnostic components.
However, visceral obesity prevalence and body mass index in 60-69 years old women were significantly lower
in equol producers than those in non-producers. Thus, equol may have an anti-obesity effect in menopause women lacking estrogen.
Soy Protein Research, Japan 22, 118-121, 2019.
Key words : equol, metabolic syndrome, menopause women
Impact of a Rice-centered Diet on Mental Health in Association with Reduced Oxidative Stress
Atsuhito TOYOMAKI*, Minori KOGA and Ichiro KUSUMI
1Department of Psychiatry, Hokkaido University Graduate School of Medicine, Sapporo 060-8638
2Department of Psychiatry, National Defense Medical College, Saitama 359-8513
ABSTRACT
Previously, we found that a Japanese diet—specifically rice and miso intake—was associated with life quality,
sleep quality, anxiety, and depression status. In that study,
a combination of rice and miso was related to mental and physical health.
Japanese diet comprises rice and other dishes with vegetables, fish, and meat.
We hypothesized that a rice-based diet intake impacts mental and physical health and aimed to investigate
the consequences of a dietary intervention with rice. This randomized, open-label,
parallel-group clinical trial included 60 participants who met the following inclusion criteria:
(1) regularly ate three meals per day and (2) ate staple foods other than rice one or more times.
Participants were randomly assigned to receive either rice-based meals or meals
with other cereals for three daily meals over two months. Participants were surveyed for sleep quality,
anxiety status, and dietary pattern before and after the experimental period.
Changes in the blood metabolite levels were assessed to investigate the biochemical changes in the body by
intervention. Sleep quality index scores showed significant improvement after the rice-based intervention.
Some metabolite levels were changed; interestingly, many of these changes were related to oxidative stress.
Since abnormal oxidative stress accumulation is suggested to be a risk factor for human health,
it is important to control oxidative stress levels to maintain health.
Although the molecular mechanisms should be investigated in detail,
our findings suggest that controlling oxidative stress
through a rice-centered intake diet may be the key for improving sleep quality.
Soy Protein Research, Japan 22, 122-125, 2019.
Key words : rice, miso, sleep quality, metabolome, oxidative stress
Development of a Breeding Technique for Selecting Disease Resistant Soybeans Based on Non-host Resistance
Masahito NAKANO* and Takafumi MUKAIHARA
Research Institute for Biological Sciences, Okayama (RIBS), Okayama 716-1241
ABSTRACT
Ralstonia solanacearum is a gram-negative bacterium causing bacterial wilt
in more than 200 plant species of over 50 botanical families.
The pathogen injects approximately 70 effector proteins into host cells via the Hrp type III secretion system during infection.
We previously identified 68 effector proteins from R. solanacearum
strain RS1000 and cloned the coding region of each effector gene into a binary vector under the constitutive promoter control.
To identify the avirulent factors possessed by R. solanacearum ,
we transiently expressed the RS1000 effector proteins in Phaseolus vulgaris leaves by agroinfiltration and
examined their ability to induce cell death in the infiltrated area. In this screening,
we observed that the expressions of clones 1, 5, 45, and 56 strongly induced cell death in P. vulgaris leaves.
The transient expressions of clones 29, 43, and 63 weakly induced cell death in the leaves.
These findings suggest that R. solanacearum possesses multiple effectors
that are recognized as avirulent factors and induced defense responses in P.vulgaris.
Soy Protein Research, Japan 22, 126-129, 2019.
Key words : Ralstonia solanacearum , Leguminous plants, disease resistance, bacterial wilt, effector protein
Isolation of a Novel Green seed Suppressor Gene in Soybean
Hiroshi YAMATANI*
Laboratory of Plant Chromosome and Gene Stock, Graduate School of Science, Hiroshima University, Hiroshima 739-8526
ABSTRACT
Chlorophyll is a molecule responsible for harvesting light energy in photosynthesis degraded during leaf senescence.
Chlorophyll degradation during senescence is controlled by genetic programs and environmental factors.
When this control mechanism is impaired, the plant becomes ‘stay-green’.
In soybean, high temperature and drought stress induce a green-seed phenotype,
resulting in deterioration of quality such as reduction of oil content in seeds.
Thus, the genetic suppression of green-seed phenotype in soybean is industrially useful.
The cytoplasmically-inherited stay-green mutant cytG in soybean retains chlorophyll in leaves during leaf senescence and
seeds during seed maturation. Interestingly, a nucleus-encoded cytG suppressor gene has been reported.
This suppressor gene is expected to stabilize seed quality even under abiotic stresses
by promoting chlorophyll degradation during seed maturation.
In this study, the author isolated the gene responsible for cytG suppression mutation.
First, the segregation ratio of green and yellow seed phenotypes in an F2 population between cytG and
cytG suppression line was observed to be about 15: 1, suggesting that two loci are involved in cytG suppression.
Rough mapping revealed that one of the two genes was located near a gene known to be involved in leaf senescence.
The gene polymorphism was perfectly linked to the suppression phenotype in 20 individuals, suggesting that
this gene is the gene described above. Sequence analysis of the paralog revealed that a large DNA fragment was inserted in the gene exon,
suggesting this paralog gene to be the other gene.
I intend to prove that these two genes are responsible for cytG suppression in future studies.
Soy Protein Research, Japan 22, 130-134, 2019.
Key words : chlorophyll, environment stress, stay-green, genetic approach
The Protective Effect of Soy Proteins on Glycation-induced Skeletal Muscle Atrophy
Tatsuro EGAWA*1, Kotaro HAGA1, Yoshitaka OHNO2, Katsumasa GOTO2 and Tatsuya HAYASHI1
1Laboratory of Health and Exercise Sciences, Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501
2Laboratory of Physiology, Graduate School of Health Sciences, Toyohashi SOZO University, Aichi 440-8511
ABSTRACT
Glycation causes retrogressive changes in skeletal muscle including deterioration of strength and mass. Recently,
it has been reported that isoflavones have an anti- glycation effect. Therefore, in this study,
we aimed to investigate the effect of soy isoflavones (daidzein, genistein, and glycitein) and equol,
a daidzein metabolite, on glycation-induced skeletal muscle atrophy.
C2C12 skeletal muscle cells were incubated with advanced glycation end products (AGEs, 0.1 mg/ml) for 48 h in the absence or
presence of 0.1μM soy proteins (daidzein, genistein, glycitein, or equol). AGEs alone induced atrophy of myotubes,
activated ubiquitin-proteasome (increased muscle RING finger 1 mRNA and phosphorylation of 5´AMP-activated protein kinase Thr172) and
autophagy systems (phosphorylation of Unc-51 like autophagy activating kinase Ser555 and decreased p62),
and promoted phosphorylation of signal transducer and activator of transcription 3 (STAT3) Tyr705. Daidzein, genistein, glycitein, and
equol partly prevented AGEs-induced myotube atrophy and activation of ubiquitin-proteasome system,
but not autophagy system. AGEs formation assay showed that daidzein and genistein inhibited AGEs formation by 40 and 21%,
respectively. In addition, glycitein and equol suppressed AGEs-induced phosphorylation of STAT3 Tyr705. In conclusion,
it is suggested that soy isoflavones (daidzein, genistein, and glycitein) and equol suppress glycation-induced muscle atrophy through
inhibiting AGEs formation and/or STAT3 activation.
Soy Protein Research, Japan 22, 135-140, 2019.
Key words : glycation, skeletal muscle, atrophy, isoflavone, equol
Effect of Shear Milling on the Modification for Soy Protein
Hideyuki UEMATSU*
Research center for fibers and materials, University of Fukui, Fukui 910-8507
ABSTRACT
The effect of shear milling on defatted soybean structure was investigated at various milling temperatures.
The milled sample size was 200μm when milled at a temperature below 60°C. On the contrary,
the milled sample size was 500μm with conventional milling apparatus.
The sedimentation of shear milled sample in aqueous solution was suppressed as compared with
that of the milled sample prepared with conventional milling apparatus.
The gelation behavior was shown in shear milled soy aqueous solution in rheological analysis that did not appear
in shear milled samples milled at a temperature above 90°C and prepared with conventional milling apparatus.
We concluded that soy protein structure could be modified to be water swellable by shear milling at below 60°C.
Soy Protein Research, Japan 22, 141-145, 2019.
Key words : shear milling, modification, soy protein, rheology, water swellable
Basic Study on High Protein and High-quality Silage Preparation Using Soybean
Tomomi KAMIZONO*
Tohoku Agricultural Research Center, NARO, Iwate 020-0198
ABSTRACT
In this study, silages were prepared at the laboratory level using soybeans as a protein feed resource and
silage preparation-associated changes in fermentation quality and protein fractions were investigated over time.
In whole-crop soybean silage, pH rapidly declined by adding lactic acid bacteria and
the V-score 60 days after ensiling indicated good fermentation quality with 90 points or more. In addition, the crude, degradable, and
binding protein contents in whole-crop soybean silage were not affected by adding lactic acid bacteria and storage time.
The soluble protein content was significantly higher at 60 days than at 0 days of storage.
In the case of soybean soft grain silage, the pH did not decline markedly, which might be related to low moisture content in
soybean grains. The binding protein content was significantly higher at 60 days than at 0 days of storage. Furthermore,
the crude, soluble, and degradable protein contents in soft grain soybean silage were not affected by adding lactic acid bacteria and
storage time. From these results, changes in silage quality and protein fractions in
the process of preparing silage of Japanese edible soybean varieties were clarified.
Soy Protein Research, Japan 22, 146- 151, 2019.
Key words : fermentation quality, lactic acid bacteria, protein fractions, silage, soybean
A Study on Isoflavonoid Metabolism Using CRISPR/Cas9 in Soybean
Kai UCHIDA*
RIKEN Center for Sustainable Resource Science, Yokohama 230-0045
ABSTRACT
Isoflavones in soybean are known to function as signals for symbiosis with Rhizobia;
however, other functions still remain to be clarified. Isoflavonoid synthase (IFS),
an essential enzyme in isoflavone biosynthesis, catalyzes isoflavonoid skeleton production.
Recently, genome editing technologies such as CRISPR/Cas9 have been extensively developed and several applications
in soybean have also been reported. However, there are no reported cases of isoflavone metabolism studies using genome editing technology.
In this study, for elucidating the isoflavone metabolism in soybean, we developed a CRISPR/Cas9 vector specialized for
genome editing in soybean and analyzed the metabolic change to establish isoflavone-free hairy root produced by the vector.
The vector specialized for soybean was prepared by introducing soybean codon-optimized SaCas9, GFP as the selection marker,
soybean U6-10 promoter for gRNA expression, and gRNA targeted IFS into pRI201-AN DNA.
Hairy root was produced by infection of Agrobacterium rhizogenes strain K599 transformed with the above vector.
Genotyping and isoflavone analysis were carried out by direct sequencing using PCR products amplified from genomic DNA extracted
from hairy root and LC-PDA analysis with methanol extract of hairy root, respectively.
Genotyping revealed that IFS genes were mutated in more than 60% of the total transformed lines and isoflavones were decreased or
not detected in almost all mutated lines. Moreover, an unknown metabolite, predicted to be chalcone,
accumulated in isoflavone-decreased lines.
This study indicated that the prepared SaCas9 construct is efficient for genome editing for soybean and
mutation in IFS gene leads to significant metabolic change and unknown metabolite accumulation.
Soy Protein Research, Japan 22, 152-156, 2019.
Key words : isoflavone, CRISPR/Cas9, SaCas9, hairy root
The Mechanism of Immune Regulation of Soybean Resistant Protein by Gut Microbiota
Tasuku OGITA*
Department of Interdisciplinary Genome Sciences and Cell Metabolism, Institute for Biomedical Sciences,
Interdisciplinary Cluster for Cutting Edge Research, Shinshu University, Nagano 399-4598
ABSTRACT
Recently, the term “resistant protein” has been used to collectively indicate dietary fiber-like functional proteins that
cannot be easily digested. In the present study, the role of soy resistant protein (SRP) in regulating biological functions was elucidated.
Little is known about the regulation of gut barrier functions of SRP and its underlying immune mechanisms.
In the intestine, Paneth cells, goblet cells, and enterocytes secrete anti-bacterial peptides,
such as regenerating islet- derived protein 3-gamma (Reg3γ). Reg3γ contributes to the regulation of bacterial colonization in the intestine,
thus activating its immune mechanisms. Interleukin-22 (IL-22) production by the innate lymphoid cells induces Reg3γ production,
]which is responsible for maintaining the gut environment balance. In this study,
SRP intake significantly increased Reg3γ and IL-22 expressions in cecal tissues.
Reg3γ levels and relative Flintibacter butyricus (FB) abundance in the cecum were observed to be positively correlated.
Next, we evaluated the effects of FB on IL-22 expression induction in vitro.
Murine splenocytes were co-cultured with 104 to 106 CFU/mL FB for 24 h. After 24 h,
qPCR-determined IL-22 mRNA expression had increased significantly after adding 106 CFU/mL FB.
Flow cytometry analysis revealed that the number of IL-22+ CD45.2+ cells were significantly increased upon adding 104 and 106 CFU/mL FB.
These results suggested that FB may be involved in IL-22 and Reg3γ production and induction.
Soy Protein Research, Japan 22, 22, 157-160, 2019.
Key words : soybean resistant protein, Reg3γ, IL-22, Flintibacter butyricus
Effects of Dietary Proteins During Lactation on the Skin in Mice Offspring
Takumi YAMANE*
Laboratory of Molecular Bioregulation, Department of Nutritional Science and Food Safety,
Faculty of Applied Bioscience, Tokyo University of Agriculture, Tokyo 156-8502
ABSTRACT
Protein malnutrition is largely associated with a delay or failure of the healing process.
However, the effect of dietary protein type on wound healing is largely unknown.
This study aimed to reveal the effect of dietary protein type on wound healing and examined its regulatory mechanisms
in a rat model of full-thickness cutaneous wounds. Wistar male rats were fed a normal dietT for a week and then divided
into three groups that were fed casein, soy protein, and gluten diets for the experimental period.
After a week of feeding experimental diets, two 1.5 cm diameter full-thickness wounds were created using sterile scissors
in the dorsolateral skin. The wound area was measured every day after wounding. No significant differences
in wound healing were observed in the soy-fed rats when compared with that in the casein-fed rats. However,
daily wound area measurements during the healing process clearly indicated that
the gluten diet suppressed wound healing five days post-wounding more than the casein diet. Our results also showed that
MMP2 activity was significantly higher in the gluten-fed rat skin than with that in the casein-fed rat skin.
In summary, this study provides evidence that a low-quality protein diet negatively effects wound healing via MMP2 activity modulation
in rats.
Soy Protein Research, Japan 22, 161-164, 2019.
Key words : wound healing, matrix metalloproteinase, dietary protein type, rat