Hitoshi Ashida

Kobe University, Kōbe, Hyōgo, Japan

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Publications (182)391.53 Total impact

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    ABSTRACT: To develop a functional food for improvement and/or prevention of diabetic nephropathy, we investigated whether catechins can activate DGKα, which is involved in the vitamin E-induced improvement of diabetic renal dysfunction. Among the catechins tested, (-)-epicatechin-3-gallate, (-)-epigallocatechin-3-gallate (EGCg), (-)-catechin-3-gallate and (-)-gallocatechin-3-gallate induced DGKα translocation from the cytoplasm to the plasma membrane, which is an index of DGKα activation. In contrast, (-)-epicatechin, (-)-epigallocatechin and gallic acid did not induce the translocation. Among the four galloylated catechins, EGCg was most effective, dose-dependent and subtype-specific among type I DGKs. Importantly, EGCg did indeed up-regulate DGKα activity. In addition, we found that a 67 kDa laminin receptor (67LR) mediates the EGCg-induced activation of DGKα, and both 67LR and DGKα are expressed in podocyte among glomerular cells. Finally, the EGCg-induced translocation of DGKα was confirmed in cultured podocytes. Thus, EGCg activates DGKα via 67LR, providing the possibility that EGCg may improve and/or prevent diabetic renal dysfunction.
    Journal of Functional Foods 05/2015; 15:561-569. DOI:10.1016/j.jff.2015.04.005 · 4.48 Impact Factor
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    ABSTRACT: Abstract Polycyclic aromatic hydrocarbons (PAHs) and halogenated aromatic hydrocarbons (HAHs) develop various adverse effects through activation of an aryl hydrocarbon receptor (AhR). The suppressive effects of brewed green tea and black tea on 3-methylcholanthrene (MC)-induced AhR activation and its downstream events were examined in the liver of rats. Ad-libitum drinking of green tea and black tea suppressed MC-induced AhR activation and elevation of ethoxyresorufin O-deethylase activity in the liver, whereas the teas themselves did not induce them. Tea showed a suppressive fashion on the expression of cytochrome P450 1A1 (CYP1A1). Tea suppressed the AhR activation induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) ex vivo. A part of catechins and theaflavins was present in plasma and liver as conjugated and intact forms. The results of this study suggested that active component(s) of tea are incorporated in the liver and suppress the activity of CYP1As through the AhR activation pathway.
    International Journal of Food Sciences and Nutrition 01/2015; 66(3):1-8. DOI:10.3109/09637486.2014.992007 · 1.20 Impact Factor
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    ABSTRACT: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) causes various toxic effects, including wasting syndrome, through activation of an aryl hydrocarbon receptor (AhR). Our previous report demonstrated that certain flavonoids inhibit the activation of AhR and suppress its DNA binding activity. In this study, we searched for an active compound among 13 flavonoids that suppressed TCDD-induced loss of lipid accumulation using 3T3-L1 adipocytes as a cell culture model for wasting syndrome. Two flavonoids, luteolin and epigallocatechin gallate, suppressed TCDD-induced loss of lipid accumulation in this model. We further investigated luteolin to clarify the underlying molecular mechanism and confirmed that luteolin inhibited nuclear translocation of AhR caused by TCDD. Luteolin also inhibited the TCDD-driven decrease in protein expression of peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer-binding protein α (C/EBPα). Although TCDD alone did not change protein expression of C/EBPβ and C/EBPδ, luteolin and TCDD up-regulated C/EBPδ expression in a dose-dependent manner. On the other hand, TCDD significantly decreased DNA binding of C/EBPβ and C/EBPδ, and luteolin completely canceled TCDD-decreased DNA binding of them. We conclude that luteolin suppresses the TCDD-induced loss of lipid accumulation in 3T3-L1 adipocytes by preventing a decrease in protein expression of PPARγ and C/EBPα, the master regulators of adipocyte differentiation and in DNA binding of C/EBPβ and C/EBPδ. Moreover, luteolin was rapidly incorporated and accumulated in 3T3-L1 adipocytes. Thus, luteolin is an attractive compound for the prevention of TCDD-induced wasting syndrome. Copyright © 2014 Elsevier Inc. All rights reserved.
    Pesticide Biochemistry and Physiology 11/2014; 120. DOI:10.1016/j.pestbp.2014.11.005 · 2.01 Impact Factor
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    ABSTRACT: Two main chalcones, 4-hydroxyderricin and xanthoangelol, from Ashitaba, which is a food ingredient and a folk medicine in Asia, have been demonstrated to modulate lipid metabolism in 3T3-L1 and HepG2 cells. In this study, we investigated the effects of Ashitaba extract on adiposity in mice fed a high-fat (HF) diet and its underlying mechanisms based on adipose tissue and hepatic lipid metabolism. C57BL/6 mice were fed a normal or HF diet supplemented with Ashitaba extract (0.01% and 0.1%, w/w) for 16 weeks. Ashitaba extract suppressed the HF diet-induced body weight gain and fat deposition in white adipose tissue, reduced plasma cholesterol, glucose, and insulin levels, increased the adiponectin level, lowered triglyceride and the liver cholesterol content, increased phosphorylation of AMP-activated protein kinase (AMPK) in adipose tissue and liver, inhibited lipogenesis in adipose tissue by down-expression of peroxisome proliferator-activated receptor (PPAR) γ, CCAAT/enhancer-binding protein α and sterol regulatory element-binding protein 1 (SREBP1), inhibited lipogenesis in the liver by down-expression of SREBP1 and its target enzyme fatty acid synthase, and promoted fatty acid oxidation by up-expression of carnitine palmitoyltransferase-1A and PPARα. In conclusion, Ashitaba extract can possibly prevent adiposity through modulating lipid metabolism through phosphorylation of AMPK in adipose tissue and liver.
    Food & Function 11/2014; 6(1). DOI:10.1039/c4fo00525b · 2.91 Impact Factor
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    ABSTRACT: It is well known that tea has a variety of beneficial impacts on human health, including anti-obesity effects. It is well documented that green tea and its constituent catechins suppress obesity, but the effects of other tea on obesity and its potential mechanisms involved are not yet fully understood. In this study, we investigated suppression of adiposity by oolong, black and pu-erh tea and characterized the underlying molecular mechanism in vivo. We found that consumption of oolong, black or pu-erh tea for a period of one week significantly decreased visceral fat without affecting body weight in male ICR mice. On a mechanistic level, consumption of tea increased phosphorylation of AMP-activated protein kinase (AMPK) in white adipose tissue (WAT). This was accompanied by the induction of WAT protein levels of uncoupling protein 1 and insulin-like growth factor binding protein 1. Our results indicate that oolong, black and pu-erh tea, in particular black tea, suppresses adiposity via phosphorylation of the key metabolic regulator AMPK and increases browning of WATs.
    07/2014; 5(10). DOI:10.1039/C4FO00095A
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    ABSTRACT: Thioredoxin (TRX) is a redox regulating protein which has protective effects against oxidative stress-induced damage to cells and tissues. In this study, we investigated the effects of orally administered TRX derived from edible yeast, Saccharomyces cerevisiae, on gastric mucosa. First, we examined the digestibility of orally administered yeast TRX in mice, and detected yeast TRX in the stomach for 4 h after administration. Next, we investigated the mitigation of gastric mucosal injury after the oral administration of yeast TRX in water-immersion restraint stress and HCl/ethanol-induced gastric ulcer models. Furthermore, we conducted DNA microarray analysis, using the HCl/ethanol-induced model, which revealed that several groups of genes related to tissue repair were upregulated in ulcer regions in the stomachs of rats administered with yeast TRX. These results demonstrated the viability of the use of oral administrations of yeast TRX to protect the gastric mucosa.
    Bioscience Biotechnology and Biochemistry 07/2014; 78(7):1221-1230. DOI:10.1080/09168451.2014.915733 · 1.21 Impact Factor
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    ABSTRACT: The present study demonstrates that glabridin, a prenylated isoflavone in licorice, stimulates glucose uptake through the adenosine monophosphate-activated protein kinase (AMPK) pathway in L6 myotubes. Treatment with glabridin for 4 h induced glucose uptake in a dose-dependent manner accompanied by the translocation of glucose transporter type 4 (GLUT4) to the plasma membrane. Glabridin needed at least 4 h to increase glucose uptake, while it significantly decreased glycogen and increased lactic acid within 15 min. Pharmacological inhibition of AMPK by compound C suppressed the glabridin-induced glucose uptake, whereas phosphoinositide 3-kinase and Akt inhibition by LY294002 and Akt1/2 inhibitor, respectively, did not. Furthermore, glabridin induced AMPK phosphorylation, and siRNA for AMPK completely abolished glabridin-induced glucose uptake. We confirmed that glabridin-rich licorice extract prevent glucose intolerance accompanied by the AMPK-dependent GLUT4 translocation in the plasma membrane of skeletal muscle. These results indicate that glabridin may possess a therapeutic effect on metabolic disorders, such as diabetes and hyperglycemia, by modulating glucose metabolism through AMPK in skeletal muscle cells.
    Molecular and Cellular Endocrinology 06/2014; 393(1-2). DOI:10.1016/j.mce.2014.06.009 · 4.24 Impact Factor
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    ABSTRACT: Drugs, xenobiotics including environmental pollutants, and certain food components modulate expression of drug-metabolizing enzymes. An aryl hydrocarbon receptor (AhR) possesses possible expression of phase I and phase II enzymes directly by binding of its ligands such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and indirectly by regulating expression of nuclear factor-erythroid-2-related factor 2 (Nrf2). Previous our result demonstrated that lueolin, a natural flavonoid existing in vegetables and herbs, competed the binding of TCDD to AhR. In the present study, we investigated the effect of luteolin on the expression of drug-metabolizing enzymes through the AhR and Nrf2 pathways. Luteolin inhibited TCDD-induced protein expression of phase I enzyme cytochrome P450 1A1 (CYP1A1), phase II enzymes NAD(P)H:quinone oxidoreductase-1 (NQO1) and glutathione-S-transferase P1 (GSTP1) in HepG2, Hepa1c1c7 and RL-34 cells in a dose-dependent manner. Luteolin suppressed TCDD- and tert-butylhydroquinone induced Nrf2 protein by decreasing its stability in HepG2 cells. In tert-butylhydroquinone treated cells, luteolin dose-dependently inhibited NQO1, GSTP1 and aldo-keto reductases (AKRs). Of these, protein expression of CYP1A1 and GSTP1 was mainly dominated by the AhR pathway, while that of NQO1 and AKRs was by the Nrf2 pathway. In conclusion, luteolin inhibits expression of phase I and phase II drug-metabolizing enzymes by modulating the AhR and Nrf2 pathways.
    Archives of Biochemistry and Biophysics 06/2014; DOI:10.1016/j.abb.2014.05.023 · 3.04 Impact Factor
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    ABSTRACT: We investigated whether rutin, a flavonoid isolated from Toona sinensis Roem, has the ability to enhance insulin-dependent receptor kinase (IRK) activity and glucose transporter 4 (GLUT4) translocation in differentiated myotubes. We also tested the effects of rutin treatment in insulin-resistant mice using an oral glucose tolerance test (OGTT). Rutin potentiated insulin receptor kinase (IRK) phosphorylation when IRK autophosphorylation was triggered by insulin in differentiated myotubes. Co-treatment of cells with rutin and insulin attenuated S961-mediated inhibition of insulin-dependent GLUT4 translocation. In S961-treated C57BL/6 mice, an in vivo model of insulin resistance and type 2 diabetes, rutin treatment showed a normoglycemic effect in the OGTT. This study shows evidence that rutin may serve as a potential agent for glycemic control through enhancement of IRK activity, thereby inducing the insulin signaling pathway causing increased GLUT4 translocation and increased glucose uptake.
    Molecular Nutrition & Food Research 06/2014; 58(6). DOI:10.1002/mnfr.201300691 · 4.91 Impact Factor
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    ABSTRACT: We searched for polyphenols capable of inhibiting the lipid accumulation in 3T3-L1 cells, and investigated the mechanisms of two effective chalcones cardamonin and flavokawain B on differentiation of preadipocytes.
    Archives of Biochemistry and Biophysics 05/2014; DOI:10.1016/j.abb.2014.05.008 · 3.04 Impact Factor
  • Tianshun Zhang, Norio Yamamoto, Hitoshi Ashida
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    ABSTRACT: Excessive lipid accumulation in the liver has been proposed to cause hyperlipidemia, diabetes and fatty liver disease. 4-Hydroxyderricin (4HD), xanthoangelol (XAG), cardamonin (CAR) and flavokawain B (FKB) are chalcones that have exhibited various biological effects against obesity, inflammation, and diabetes; however, little is known about the inhibitory effects of these chalcones on fatty liver disease. In the present study, we investigated the ability of 4HD, XAG, CAR, and FKB to reduce lipid accumulation in hepatocytes. When HepG2 cells were treated with a mixture of fatty acids (FAs; palmitic acid : oleic acid = 1 : 2 ratio), significant lipid accumulation was observed. Under the same experimental conditions, addition of chalcones at 5 μM significantly suppressed the FA-induced lipid accumulation. We found that the expression of sterol regulatory element-binding protein-1 (SREBP-1), a key molecule involved in lipogenesis, was decreased in these chalcone-treated cells. We also found that these chalcones increased the expression of peroxisome proliferator-activated receptor α (PPARα), which is involved in FA oxidation. Moreover, these chalcones increased phosphorylation of AMP-activated protein kinase (AMPK) and liver kinase B1 (LKB1), upstream regulators of SREBP-1 and PPARα. We confirmed that an AMPK inhibitor, compound C, reversed chalcone-induced changes in SREBP-1 and PPARα expression in the HepG2 cells. Collectively, we found that 4HD, XAG, CAR, and XAG attenuated lipid accumulation through activation of the LKB1/AMPK signaling pathway in HepG2 cells.
    04/2014; 5(6). DOI:10.1039/c3fo60694e
  • Sayuri Shimazu, Masaya Ohta, Hitoshi Ashida
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    ABSTRACT: The aim of this study is to elucidate the effect of lipid extracts from Solidago canadensis for phytomonitoring of polychlorinated biphenyl (PCB) 126 in the transgenic Arabidopsis plant XgD2V11-6 carrying the recombinant guinea pig (g) aryl hydrocarbon receptor (AhR)-mediated β-glucuronidase (GUS) reporter gene expression system. A lipid extract was prepared from S. canadensis and separated into simple lipid, glycolipid, and phospholipid fractions by silica gel column chromatography. Sterylglucoside (SG), monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), and glucosyl ceramide were found in the glycolipid fraction. When the transgenic Arabidopsis plants were treated with the glycolipid fraction together with PCB126, PCB126-induced GUS activity significantly increased in the whole plant. Moreover, S. canadensis-derived SG, MGDG, and DGDG also significantly increased PCB126-induced GUS activity. These results indicated that glycolipids in S. canadensis enhanced the sensitivity of this monitoring assay.
    Science of The Total Environment 02/2014; DOI:10.1016/j.scitotenv.2014.01.090 · 4.10 Impact Factor
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    ABSTRACT: Although the underlying mechanism is unclear, β-conglycinin (βCG), the major component of soy proteins, regulates blood glucose levels. Here, we hypothesized that consumption of βCG would normalize blood glucose levels by ameliorating insulin resistance and stimulating glucose uptake in skeletal muscles. To test our hypothesis, we investigated the antidiabetic action of βCG in spontaneously diabetic Goto-Kakizaki (GK) rats. Our results revealed that plasma adiponectin levels and adiponectin receptor 1 messenger RNA expression in skeletal muscle were higher in βCG-fed rats than in casein-fed rats. Phosphorylation of adenosine monophosphate-activated protein kinase (AMP kinase) but not phosphatidylinositol-3 kinase was activated in βCG-fed GK rats. Subsequently, βCG increased translocation of glucose transporter 4 to the plasma membrane. Unlike the results in skeletal muscle, the increase in adiponectin receptor 1 did not lead to AMP kinase activation in the liver of βCG-fed rats. The down-regulation of sterol regulatory element-binding factor 1, which is induced by low insulin levels, promoted the increase in hepatic insulin receptor substrate 2 expression. Based on these findings, we concluded that consumption of soy βCG improves glucose uptake in skeletal muscle via AMP kinase activation and ameliorates hepatic insulin resistance and that these actions may help normalize blood glucose levels in GK rats.
    Nutrition research 02/2014; 34(2):160-7. DOI:10.1016/j.nutres.2013.12.001 · 2.59 Impact Factor
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    ABSTRACT: Resveratrol (3,4',5-trihydroxy-trans-stilbene) is known to enhance the cytotoxicity of the anticancer drug doxorubicin. On the other hand, breast cancer MCF-7 cells acquire resistance to doxorubicin under hypoxic conditions. In this study, we investigated the effect of resveratrol on hypoxia-induced resistance to doxorubicin in MCF-7 cells. Resveratrol and its derivative 3,5-dihydroxy-4'-methoxy-trans-stilbene, but not 3,5-dimethoxy-4'-hydroxy-trans-stilbene, cancelled hypoxia-induced resistance to doxorubicin at a concentration of 10 μM. Carbonyl reductase 1 (CBR1) catalyzes the conversion of doxorubicin to its metabolite doxorubicinol, which is much less effective than doxorubicin. Hypoxia increased the expression of CBR1 at both mRNA and protein levels, and knockdown of CBR1 inhibited hypoxia-induced resistance to doxorubicin in MCF-7 cells. Knockdown of hypoxia-inducible factor (HIF)-1α repressed the hypoxia-induced expression of CBR1. Resveratrol repressed the expression of HIF-1α protein, but not HIF-1α mRNA, and decreased hypoxia-activated HIF-1 activity. Resveratrol repressed the hypoxia-induced expression of CBR1 at both mRNA and protein levels. Likewise, 3,5-dihydroxy-4'-methoxy-trans-stilbene decreased the hypoxia-induced expression of CBR1 protein, but not 3,5-dimethoxy-4'-hydroxy-trans-stilbene. Furthermore, resveratrol decreased the expression of HIF-1α protein even in the presence of the proteasome inhibitor MG132 in hypoxia. Theses results indicate that in MCF-7 cells, HIF-1α-increased CBR1 expression plays an important role in hypoxia-induced resistance to doxorubicin and that resveratrol and 3,5-dihydroxy-4'-methoxy-trans-stilbene decrease CBR1 expression by decreasing HIF-1α protein expression, perhaps through a proteasome-independent pathway, and consequently repress hypoxia-induced resistance to doxorubicin.
    Journal of Nutritional Science and Vitaminology 01/2014; 60(2):122-8. DOI:10.3177/jnsv.60.122 · 0.87 Impact Factor
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    ABSTRACT: The Japanese herb, Ashitaba (Angelica keiskei Koidzumi), contains two prenylated chalcones, 4-hydroxyderricin and xanthoangelol, which are considered to be the major active compounds of Ashitaba. However, their effects on inflammatory responses are poorly understood. In the present study, we investigated the effects and underlying molecular mechanisms of 4-hydroxyderricin and xanthoangelol on lipopolysaccharide (LPS)-induced inflammatory responses in RAW264 mouse macrophages. LPS-mediated production of nitric oxide (NO) was markedly reduced by 4-hydroxyderricin (10 μM) and xanthoangelol (5 μM) compared with their parent compound, chalcone (25 μM). They also inhibited LPS-induced secretion of tumor necrosis factor-alpha (TNF-α), and gene and protein expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2). Although chalcone decreased the DNA-binding activity of both activator protein-1 (AP-1) and nuclear factor-kappa B (NF-κB), 4-hydroxyderricin and xanthoangelol suppressed only AP-1 and had no effect on NF-κB. On the other hand, all of the tested chalcones reduced the phosphorylation (at serine 536) level of the p65 subunit of NF-κB. 4-Hydroxyderricin and xanthoangelol may be promising for the prevention of inflammatory diseases.
    Journal of Agricultural and Food Chemistry 12/2013; 62(2). DOI:10.1021/jf404175t · 3.11 Impact Factor
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    ABSTRACT: Based on a recent study indicating that enzymatically synthesized glycogen (ESG) possesses a dietary, fiber-like action, we hypothesized that ESG can reduce the risk of obesity. In this study, the antiobesity effects of ESG were investigated in a model of diet-induced obesity. Male Sprague-Dawley rats were divided into 4 groups and fed a normal or high-fat diet, with or without 20% ESG, for 4 weeks. Body weight, food intake, lipid deposition in the white adipose tissues and liver, fecal lipid excretion, and plasma lipid profiles were measured. At week 3, the body fat mass was measured using an x-ray computed tomography system, which showed that ESG significantly suppressed the high-fat diet-induced lipid accumulation. Similar results were observed in the weight of the adipose tissue after the experiment. Moreover, ESG significantly suppressed the lipid accumulation in the liver but increased fecal lipid excretion. The plasma concentrations of triacylglycerol and nonesterified fatty acid were lowered after a high-fat diet, whereas the total bile acid concentration was increased by ESG. However, the hepatic messenger RNA (mRNA) levels of enzymes related to lipid metabolism were not affected by ESG. Conversely, the mRNA levels of long-chain acyl-CoA dehydrogenase and medium-chain acyl-CoA dehydrogenase were up-regulated by ESG in the muscle. These results suggest that the combined effects of increased fecal lipid excretion, increased mRNA levels of enzymes that oxidize fatty acids in the muscle, and increased total bile acid concentration in the plasma mediate the inhibitory effect of ESG on lipid accumulation.
    Nutrition research 09/2013; 33(9):743-52. DOI:10.1016/j.nutres.2013.06.006 · 2.59 Impact Factor
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    ABSTRACT: Previously, we developed enzymatically synthesized glycogen (ESG) from starch, and showed its immunomodulatory and dietary fiber-like activities. In this study, we investigated the metabolism of ESG and its immunomodulatory activity using differentiated Caco-2 cells as a model of the intestinal barrier. In a co-culture system consisting of differentiated Caco-2 cells and RAW264.7 macrophages, mRNA expression of IL-6, IL-8, IL-1β and BAFF cytokines was up-regulated in Caco-2 cells and IL-8 production in basolateral medium was induced after 24 h apical treatment with 5 mg ml(-1) of ESG. The mRNA level of iNOS was also up-regulated in RAW264.7 macrophages. After characterization of the binding of anti-glycogen monoclonal antibodies (IV58B6 and ESG1A9) to ESG and its digested metabolite resistant glycogen (RG), an enzyme-linked immunosorbent assay (ELISA) system was developed to quantify ESG and RG. Using this system, we investigated the metabolism of ESG in differentiated Caco-2 cells. When ESG (7000 kDa, 5 mg ml(-1)) was added to the apical side of Caco-2 monolayers, ESG disappeared and RG (about 3000 kDa, 3.5 mg ml(-1)) appeared in the apical solution during a 24 h incubation. Neither ESG nor RG was detected in the basolateral solution. In addition, both ESG and RG were bound to TLR2 in Caco-2 cells. In conclusion, we suggest that ESG is metabolized to a RG-like structure in the intestine, and this metabolite activates the immune system via stimulation of the intestinal epithelium, although neither ESG nor its metabolite could permeate the intestinal cells under our experimental conditions. These results provide evidence for the beneficial function of ESG as a food ingredient.
    07/2013; DOI:10.1039/c3fo60035a
  • Manabu Ueda, Kaori Hayashibara, Hitoshi Ashida
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    ABSTRACT: It is well known that propolis has the ability to prevent hyperglycemia. However, the underlying mechanism is not yet fully understood. We therefore investigated whether a Brazilian propolis ethanol extract affects glucose uptake and translocation of insulin-sensitive glucose transporter (GLUT) 4 in skeletal muscle cells. In L6 myotubes, the extract at 1 μg/mL significantly promoted GLUT4 translocation and glucose uptake activity. Regarding the mechanism of GLUT4 translocation, propolis extract induced both PI3K and AMPK phosphorylation in a dose-dependent manner in L6 myotubes. However, we could not define which pathway was preferentially associated with GLUT4 translocation, because both PI3K and AMPK inhibitors revealed off-target effects to each other. The main polyphenols found in the propolis extract, artepillin C, coumaric acid, and kaempferide, promoted GLUT4 translocation in L6 myotubes. Additionally, these compounds activated both PI3K- and AMPK-dependent dual-signaling pathways. However, only kaempferide increased glucose uptake activity under our experimental conditions. Single oral administrations of propolis extract, at 250 mg/kg body weight, lowered postprandial blood glucose levels in ICR mice. The extract promoted GLUT4 translocation in skeletal muscle of rats and mice, but did not inhibit α-glucosidase activity in the small intestine under our experimental conditions. It was confirmed that propolis extract promoted phosphorylation of both PI3K and AMPK in rat skeletal muscle. In conclusion, we show that Brazilian propolis has the potential to prevent hyperglycemia through the promotion of GLUT4 translocation in skeletal muscle and that kaempferide is one of the candidates for active compound in propolis. © 2013 BioFactors, 2013.
    BioFactors 07/2013; 39(4). DOI:10.1002/biof.1085 · 3.00 Impact Factor
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    ABSTRACT: Scope10-Hydroxy-2-decenoic acid (10H2DA) is one of the unique medium-chain fatty acids (MCFAs) specifically found in royal jelly. We hypothesize that 10H2DA has multiple biological functions and may aid in 5-AMP-activated protein kinase (AMPK) activation and affect the glucose transport system in skeletal muscle. Methods and resultsWe examined whether various MCFAs present in royal jelly activated AMPK. Treatment of L6 myotubes with various MCFAs showed that 10H2DA administration resulted in a significant increase in phosphorylated AMPK. 10H2DA activates AMPK independently of insulin and significantly increased glucose uptake into L6 myotubes following translocation of glucose transporter 4 (Glut4) to the plasma membrane (PM). The activation was induced by the upstream kinase Ca2+/calmodulin-dependent kinase kinase , but was independent of changes in AMP:ATP ratio and the liver kinase B1 pathway. Oral administration of 10H2DA significantly stimulated phosphorylation of AMPK and Glut4 translocation to the PM in mouse skeletal muscle. Conclusion These findings indicate that (i) 10H2DA activates AMPK, and insulin independently enhances glucose uptake following translocation of Glut4 to PM, (ii) activation of AMPK by 10H2DA is mediated via extracellular Ca2+-dependent Ca2+/calmodulin-dependent kinase kinase , without alteration in the AMP:ATP ratio, and liver kinase B1 was not involved in the activation.
    Molecular Nutrition & Food Research 06/2013; 57(10). DOI:10.1002/mnfr.201300041 · 4.91 Impact Factor
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    ABSTRACT: Black soybean seed coat has abundant levels of polyphenols such as anthocyanins (cyanidin 3-glucoside; C3G) and procyanidins (PCs). In this study, we found that dietary black soybean seed coat extract (BE) ameliorates hyperglycemia and insulin sensitivity via the activation of AMP-activated protein kinase (AMPK) in type 2 diabetic mice. Dietary BE significantly reduced blood glucose levels and enhanced insulin sensitivity. AMPK was activated in the skeletal muscle and liver of diabetic mice fed BE. This activation was accompanied by the upregulation of glucose transporter 4 in skeletal muscle and the downregulation of gluconeogenesis in the liver. These changes resulted in improved hyperglycemia and insulin sensitivity in type 2 diabetic mice. In vitro studies using L6 myotubes showed that C3G and PCs significantly induced AMPK activation and enhanced glucose uptake into the cells.
    Journal of Agricultural and Food Chemistry 05/2013; 61(23). DOI:10.1021/jf401190y · 3.11 Impact Factor

Publication Stats

3k Citations
391.53 Total Impact Points

Institutions

  • 1970–2015
    • Kobe University
      • • Department of Agrobioscience
      • • Graduate School of Agricultural Science
      • • Department of Biofunctional Chemistry
      • • Faculty of Agriculture
      Kōbe, Hyōgo, Japan
  • 2011
    • Wuhan University
      • Department of Chemistry
      Wuhan, Hubei, China
  • 2009
    • University of Shizuoka
      • Institute for Environmental Sciences
      Shizuoka-shi, Shizuoka-ken, Japan
  • 2006
    • The University of Tokyo
      • Department of Applied Biological Chemistry
      Tokyo, Tokyo-to, Japan
  • 2003
    • Meiji University
      • Department of Life Sciences
      Edo, Tōkyō, Japan