Intake of mulberry 1-deoxynojirimycin prevents diet-induced obesity through increases in adiponectin in mice

Identification of Characteristic Components and Foodstuffs in Healthy Japanese Diet and the Health Effects of a Diet with Increased Use Frequency of these Foodstuffs

SCOPE

Our recent study showed that the 1975 Japanese diet exhibited strong health benefits. In the current study, we aimed to develop a diet with even higher health benefits.

METHODS

First, to determine the characteristic components in the 1975 diet, we used mass spectrometry for analysis of Japanese diets from several years and performed principal component analysis. Next, a diet with an increased use frequency of foodstuffs contained characteristic components (the modified diet) was prepared and fed to mice.

RESULTS

Performed principal component analysis revealed that the 1975 diet contained 14 characteristic components that were found in fish, fruits, vegetables, seaweed, soybean foods, soup stock "dashi", and fermented seasoning. Based on these, the modified diet was prepared and fed to mice. The liver total cholesterol and serum LDL cholesterol decreased significantly in mice fed the modified diet and serum total cholesterol showed a downward trend, compared to mice fed the 1975 diet. There was no difference between the modified diet and the control groups. In addition, serum adiponectin level increased in mice fed the modified diet and serum TBARS and IL-6 levels decreased.

CONCLUSION

By modifying the 1975 diet, it was possible to make a diet with more benefit.

Central Administration of 1-Deoxynojirimycin Attenuates Hypothalamic Endoplasmic Reticulum Stress and Regulates Food Intake and Body Weight in Mice with High-Fat Diet-Induced Obesity

The α-glucosidase inhibitor, 1-deoxynojirimycin (DNJ), is widely used for its antiobesity and antidiabetic effects. Researchers have demonstrated that DNJ regulates body weight by increasing adiponectin levels, which affects energy intake and prevents diet-induced obesity. However, the mechanism by which centrally administered DNJ exerts anorexigenic effects has not been studied until now. We investigated the effect of DNJ in the hypothalamus of mice with high-fat diet-induced obesity. Results showed that intracerebroventricular (ICV) administration of DNJ reduced hypothalamic ER stress, which activated the leptin-induced Janus-activated kinase 2 (JAK2)/signal transducers and activators of transcription 3 (STAT3) signaling pathway to cause appetite suppression. We conclude that DNJ may reduce obesity by moderating feeding behavior and ER stress in the hypothalamic portion of the central nervous system (CNS).

Intake of mulberry 1-deoxynojirimycin prevents colorectal cancer in mice

The effect of 1-deoxynojirimycin, a caloric restriction mimetic, was examined in ICR mice with azoxymethane dextran sodium sulfate-induced colorectal cancer. Azoxymethane is a carcinogen (10 mg/kg body weight), and 2% dextran sodium sulfate (w/v) used as a colitis-inducing agent. Mice were separated into 5 groups: a group without colorectal cancer fed a normal diet (CO– group), and groups with colorectal cancer fed a normal diet (CO+ group), a calorie-restricted diet (caloric restriction group), and diets including 0.02% and 0.1% 1-deoxynojirimycin (l-1-deoxynojirimycin and H-1-deoxynojirimycin groups). The tumor incidence and number were reduced significantly in the caloric restriction group compared to the CO+ group, and were also suppressed in a dose-dependent manner by 1-deoxynojirimycin. mRNA for anti-apoptotic Bcl-2 was decreased and that for pro-apoptotic Bax was increased in the carcinoma tissue of CR, l-1-deoxynojirimycin and H-1-deoxynojirimycin groups. These results suggest that caloric restriction and 1-deoxynojirimycin inhibit growth of colorectal cancer by inducing apoptosis in an induced cancer model in mice.

Troxerutin Attenuates Enhancement of Hepatic Gluconeogenesis by Inhibiting NOD Activation-Mediated Inflammation in High-Fat Diet-Treated Mice

Recent evidence suggests that troxerutin, a trihydroxyethylated derivative of natural bioflavonoid rutin, exhibits beneficial effects on diabetes-related symptoms. Here we investigated the effects of troxerutin on the enhancement of hepatic gluconeogenesis in high-fat diet (HFD)-treated mice and the mechanisms underlying these effects. Mice were divided into four groups: Control group, HFD group, HFD + Troxerutin group, and Troxerutin group. Troxerutin was treated by daily oral administration at doses of 150 mg/kg/day for 20 weeks. Tauroursodeoxycholic acid (TUDCA) was used to inhibit endoplasmic reticulum stress (ER stress). Our results showed that troxerutin effectively improved obesity and related metabolic parameters, and liver injuries in HFD-treated mouse. Furthermore, troxerutin significantly attenuated enhancement of hepatic gluconeogenesis in HFD-fed mouse. Moreover, troxerutin notably suppressed nuclear factor-κB (NF-κB) p65 transcriptional activation and release of inflammatory cytokines in HFD-treated mouse livers. Mechanismly, troxerutin dramatically decreased Nucleotide oligomerization domain (NOD) expression, as well as interaction between NOD1/2 with interacting protein-2 (RIP2), by abating oxidative stress-induced ER stress in HFD-treated mouse livers, which was confirmed by TUDCA treatment. These improvement effects of troxerutin on hepatic glucose disorders might be mediated by its anti-obesity effect. In conclusion, troxerutin markedly diminished HFD-induced enhancement of hepatic gluconeogenesis via its inhibitory effects on ER stress-mediated NOD activation and consequent inflammation, which might be mediated by its anti-obesity effect.

1-Deoxynojirimycin: Occurrence, Extraction, Chemistry, Oral Pharmacokinetics, Biological Activities and In Silico Target Fishing

1-Deoxynojirimycin (DNJ, C₆H13NO₄, 163.17 g/mol), an alkaloid azasugar or iminosugar, is a biologically active natural compound that exists in mulberry leaves and Commelina communis (dayflower) as well as from several bacterial strains such as Bacillus and Streptomyces species. Deoxynojirimycin possesses antihyperglycemic, anti-obesity, and antiviral features. Therefore, the aim of this detailed review article is to summarize the existing knowledge on occurrence, extraction, purification, determination, chemistry, and bioactivities of DNJ, so that researchers may use it to explore future perspectives of research on DNJ. Moreover, possible molecular targets of DNJ will also be investigated using suitable in silico approach.

Effects of Applied Nitrogen Amounts on the Functional Components of Mulberry (Morus alba L.) Leaves

This study investigated the effects of applied nitrogen amounts on specific functional components in mulberry (Morus alba L.) leaves. The relationships between mineral elements and the functional components in mulberry leaves were examined using mulberry trees cultivated in different soil conditions in four cultured fields. Then, the relationships between the nitrogen levels and the leaf functional components were studied by culturing mulberry in plastic pots and experimental fields. In the common cultured fields, total nitrogen was negatively correlated with the chlorogenic acid content (R(2) = -0.48) and positively correlated with the 1-deoxynojirimycin content (R(2) = 0.60). Additionally, differences in nitrogen fertilizer application levels affected each functional component in mulberry leaves. For instance, with increased nitrogen levels, the chlorogenic acid and flavonol contents significantly decreased, but the 1-deoxynojirimycin content significantly increased. Selection of the optimal nitrogen application level is necessary to obtain the desired functional components from mulberry leaves.

Effect of solar radiation on the functional components of mulberry (Morus alba L.) leaves

BACKGROUND

The functional components of mulberry leaves have attracted the attention of the health food industry, and increasing their concentrations is an industry goal. This study investigated the effects of solar radiation, which may influence the production of flavonol and 1-deoxynojirimycin (DNJ) functional components in mulberry leaves, by comparing a greenhouse (poor solar radiation) and outdoor (rich solar radiation) setting.

RESULTS

The level of flavonol in leaves cultivated in the greenhouse was markedly decreased when compared with those cultivated outdoors. In contrast, the DNJ content in greenhouse-cultivated plants was increased only slightly when compared with those cultivated outdoors. Interestingly, the flavonol content was markedly increased in the upper leaves of mulberry trees that were transferred from a greenhouse to the outdoors compared with those cultivated only in the outdoors.

CONCLUSION

Solar radiation conditions influence the synthesis of flavonol and DNJ, the functional components of mulberry leaves. Under high solar radiation, the flavonol level becomes very high but the DNJ level becomes slightly lower, suggesting that the impact of solar radiation is great on flavonol but small on DNJ synthesis. © 2016 Society of Chemical Industry.

1-Deoxynojirimycin Alleviates Insulin Resistance via Activation of Insulin Signaling PI3K/AKT Pathway in Skeletal Muscle of db/db Mice

1-Deoxynojirimycin (DNJ) is widely used for the treatment of diabetes mellitus as an inhibitor of intestinal α-glucosidase. However, there are few reports about its effect on insulin sensitivity improvement. The aim of the present study was to investigate whether DNJ decreased hyperglycemia by improving insulin sensitivity. An economical method was established to prepare large amounts of DNJ. Then, db/db mice were treated with DNJ intravenously (20, 40 and 80 mg·kg(-1)·day(-1)) for four weeks. Blood glucose and biochemical analyses were conducted to evaluate the therapeutic effects on hyperglycemia and the related molecular mechanisms in skeletal muscle were explored. DNJ significantly reduced body weight, blood glucose and serum insulin levels. DNJ treatment also improved glucose tolerance and insulin tolerance. Moreover, although expressions of total protein kinase B (AKT), phosphatidylinositol 3 kinase (PI3K), insulin receptor beta (IR-β), insulin receptor substrate-1 (IRS1) and glucose transporter 4 (GLUT4) in skeletal muscle were not affected, GLUT4 translocation and phosphorylation of Ser473-AKT, p85-PI3K, Tyr1361-IR-β and Tyr612-IRS1 were significantly increased by DNJ treatment. These results indicate that DNJ significantly improved insulin sensitivity via activating insulin signaling PI3K/AKT pathway in skeletal muscle of db/db mice.

Chronic adjunction of 1-deoxynojirimycin protects from age-related behavioral and biochemical changes in the SAMP8 mice

Several studies have indicated that a caloric restriction mimetic or treatment for type 2 diabetes may reverse brain aging. Therefore, we investigated the effect of 1-deoxynojirimycin (DNJ), an alkaloid acting as an inhibitor of α-glucosidase, on age-related behavioral and biochemical changes. SAMP8 mice were randomly assigned to a control group labeled "old" or to the 10- or 20-mg/kg/day DNJ groups. The mice in the DNJ groups were administered DNJ orally from 3 to 9 months of age, and then, a "young" control group was added to analyze the age effect. The old controls exhibited significant declines in sensorimotor ability, open-field anxiety, spatial and nonspatial memory abilities, and age-related biochemical changes, including decreased serum insulin level; increased levels of insulin-like growth factor 1 receptor, presynaptic protein synaptotagmin-1, and astrocyte activation; and decreased levels of insulin receptor, brain-derived neurotrophic factor, presynaptic protein syntaxin-1, and acetylation of histones H4 at lysine 8 in the dorsal hippocampus. Significant correlations exist between the age-related behavioral deficits and the serological and histochemical data. Chronic DNJ treatment alleviated these age-related changes, and the 20-mg/kg/day DNJ group showed more significant improvement. Thus, DNJ may have the potential to maintain successful brain aging.

High-fat diet intake from senescence inhibits the attenuation of cell functions and the degeneration of villi with aging in the small intestine, and inhibits the attenuation of lipid absorption ability in SAMP8 mice

We examined the effect of a high-fat diet from senescence as a means of preventing malnutrition among the elderly. The senescence-accelerated mouse P8 was used and divided into three groups. The 6C group was given a normal diet until 6 months old. The 12N group was given a normal diet until 12 months old. The 12F group was given a normal diet until 6 months old and then a high-fat diet until 12 months old. In the oral fat tolerance test, there was a decrease in area under the curve for serum triacylglycerol level in the 12N group and a significant increase in the 12F group, suggesting that the attenuation of lipid absorption ability with aging was delayed by a high-fat diet from senescence. To examine this mechanism, histological analysis in the small intestine was performed. As a result, the degeneration of villi with aging was inhibited by the high-fat diet. There was also a significant decrease in length of villus in the small intestine in the 12N group and a significant increase in the 12F group. The high-fat diet from senescence inhibited the degeneration of villi with aging in the small intestine, and inhibited the attenuation of lipid absorption ability.

High Dietary Fat Intake during Lactation Promotes the Development of Social Stress-Induced Obesity in the Offspring of Mice

This study examined how a maternal high-fat diet (HD) during lactation and exposure of offspring to isolation stress influence the susceptibility of offspring to the development of obesity. C57BL/6J mice were fed a commercial diet (CD) during pregnancy and a CD or HD during lactation. Male offspring were weaned at three weeks of age, fed a CD until seven weeks of age, and fed a CD or HD until 11 weeks of age. Offspring were housed alone (isolation stress) or at six per cage (ordinary circumstances). Thus, offspring were assigned to one of eight groups: dams fed a CD or HD during lactation and offspring fed a CD or HD and housed under ordinary circumstances or isolation stress. Serum corticosterone level was significantly elevated by isolation stress. High-fat feeding of offspring reduced their serum corticosterone level, which was significantly elevated by a maternal HD. A maternal HD and isolation stress had combined effects in elevating the serum corticosterone level. These findings suggest that a maternal HD during lactation enhances the stress sensitivity of offspring. White adipose tissue weights were significantly increased by a maternal HD and isolation stress and by their combination. In addition, significant adipocyte hypertrophy was induced by a maternal HD and isolation stress and exacerbated by their combination. Thus, a maternal HD and isolation stress promote visceral fat accumulation and adipocyte hypertrophy, accelerating the progression of obesity through their combined effects. The mechanism may involve enhanced fatty acid synthesis and lipid influx from blood into adipose tissue. These findings demonstrate that a maternal HD during lactation may increase the susceptibility of offspring to the development of stress-induced obesity.

Mulberry 1-Deoxynojirimycin Inhibits Adipogenesis by Repression of the ERK/PPARγ Signaling Pathway in Porcine Intramuscular Adipocytes

Intramuscular fat (IMF), which is modulated by adipogenensis of intramuscular adipocytes, plays a key role in pork quality associated with marbling, juiceness, and flavor. However, the regulatory mechanism of 1-deoxynojirimycin (DNJ) on adipogenesis is still unknown. Here, we found that both DNJ (2.0, 3.0, 4.0, 5.0, and 6.0 μM) and rosiglitazone (RSG; 0.1, 0.2, 0.3, 0.4, and 0.5 mM) had no effect on cell viability. Moreover, 4 μM DNJ significantly inhibited adipogenesis, whereas 0.4 mM RSG increased lipogenesis of porcine intramuscular adipocytes. Interestingly, DNJ sharply inhibited phosphorylation of extracellular regulated protein kinases 1/2 (ERK1/2), but did not change phosphorylation of AKT (protein kinase B) in intramuscular adipocytes. We further found that the inhibitory adipogenesis of DNJ was attenuated by RSG via up-regulation of PPARγ. On the basis of the above findings, we suggest that DNJ inhibited adipogenesis through the ERK/PPARγ signaling pathway in porcine intramuscular adipocytes.

A 1H-NMR Based Study on Hemolymph Metabolomics in Eri Silkworm after Oral Administration of 1-Deoxynojirimycin

We aimed to investigate whether 1-deoxynojirimycin (DNJ) modulates glycometabolism and has toxicity in Eri silkworm (Samia cynthia ricini, Saturniidae). In this paper, hemolymph metabolites were used to explore metabolic changes after oral administration of DNJ or mulberry latex and to characterize the biological function of DNJ at the metabolic and systemic levels. Hemolymph samples were collected from fourth-instar larvae of Eri silkworm and ex-vivo high-resolution 1H nuclear magnetic resonance (NMR) spectra were acquired from the collected hemolymph samples. Then the obtained spectra were analyzed by principal component analysis (PCA) and independent-samples t-test. Metabolic pattern recognition analysis of hemolymph samples indicated that the groups of 0.25% DNJ, latex, and the mixture of 0.5% DNJ and latex (1:1) were significantly different from the control group. Moreover, compared to the control group, the groups of 0.25% DNJ, latex, and the mixture of 0.5% DNJ and latex (1:1) showed the decreased levels of citrate, succinate, fumarate, malate, and glutamine in hemolymph, the groups of 0.25% DNJ and the mixture of 0.5% DNJ and latex (1:1) showed the increased levels of trehalose and lactate. In addition, mulberry leaves exude latex was highly toxic to Eri silkworm because rich unidentified high-molecular-weight factor (s) acted as toxic substances. In our results, latex caused 20 deaths among 50 fourth-instar larvae of Eri silkmoth, but DNJ or the mixture did not caused death. All these results suggest that DNJ has a positive impact on the reverse glycometabolism by modulating glycometabolism and inhibiting glucogenesis and energy metabolism. DNJ is a secure substance as a single-ingredient antidiabetic medicine due to its nontoxicity and bioactivity.

1-deoxynojirimycin isolated from Bacillus subtilis improves hepatic lipid metabolism and mitochondrial function in high-fat-fed mice

The aim of this study was to determine whether 1-deoxynojirimycin (DNJ) isolated from Bacillus subtilis MORI beneficially influences lipid metabolism and mitochondrial function in the liver of mice fed a high-fat diet in addition to the anti-obesity properties of DNJ. Male C57BL/6 mice (n = 29; 5 weeks old) were randomly assigned to three groups: normal control diet (CTL, n = 10), high-fat diet (HF, n = 10), and high-fat diet supplemented with DNJ (DNJ, n = 9). After 12 weeks, the HF group exhibited higher overall weight gain, of the liver, and of various fat pads than the CTL and DNJ groups did. The HF group also showed greater expression of C/EBPα and CD36 mRNA in the liver than that in the CTL and/or DNJ groups. In addition, mRNA expressions of AAC and FAS were lower, while mRNA expression of PGC-1β was higher in the liver of the DNJ group than that of the HF group. The hepatic expression of p-AMPK/AMPK was higher in the DNJ group than in the HF group. This study provides novel insight into the protective effect of DNJ supplementation against obesity-induced hepatic lipid abnormalities and mitochondrial dysfunction.

Chemical constituents of Morus alba L. and their inhibitory effect on 3T3-L1 preadipocyte proliferation and differentiation

Mulberry leaf, an important traditional Chinese medicine, possesses many biological activities, including effects of anti-obesity. However, which constituents of mulberry leaf are responsible for its anti-adipogenic action is unclear. This study primarily investigated the chemical constituents from mulberry leaf and their bioactivity on the proliferation and differentiation of 3T3-L1 preadipocytes. A new flavane derivative, (2S)-4'-hydroxy-7-methoxy-8-prenylflavan (1), together with twelve known compounds including three flavanes (2-4), three chalcones (5-7), two flavones (8-9), two benzofurans (10-11) and two coumarin (12-13) was isolated from mulberry leaf. The structure of the new compound was elucidated by various spectroscopic methods including UV, HR-ESI-MS, (1)H and (13)C NMR and CD. The results of activity screening showed that compound 2, 6 and 7 inhibited the proliferation and differentiation of 3T3-L1 preadipocytes.

Response surface optimized extraction of 1-deoxynojirimycin from mulberry leaves (Morus alba L.) and preparative separation with resins

In the present study, the extraction technology and preparative separation of 1-deoxynojirimycin from mulberry leaves were systematically investigated. Four extraction parameters (ethanol concentration, extraction temperature, extraction time and ratio of solvent to sample) were explored by response surface methodology (RSM). The results indicated that the maximal yield of 1-deoxynojirimycin was achieved with an ethanol concentration of 55%, extraction temperature of 80 °C, extraction time of 1.2 h and ratio of solvent to sample of 12:1. The extraction yield under these optimum conditions was found to be 256 mg/100 g dry mulberry leaves. A column packed with a selected resin was used to perform dynamic adsorption and desorption tests to optimize the separation process. The results show that the preparative separation of 1-deoxynojirimycin from mulberry leaves can be easily and effectively done by adopting 732 resin. In conclusion, 732 resin is the most appropriate for the separation of 1-deoxynojirimycin from other components in mulberry leaves extracts, and its adsorption behavior can be described with Langmuir isotherms and a two-step adsorption kinetics model. The recovery and purity of 1-deoxynojirimycin in the final product were 90.51% and 15.3%, respectively.

Inhibition of major virulence pathways of Streptococcus mutans by quercitrin and deoxynojirimycin: a synergistic approach of infection control

OBJECTIVES

To evaluate the synergistic effect of Quercitrin and Deoxynojirimycin (DNJ) together with their individual inhibitory effect against virulence pathways of Streptococcus mutans.

METHODOLOGY

MICs of both the compounds were determined by the microdilution method, followed by their in vitrosynergy using checkerboard and time kill assay. The nature of interaction was classified as synergistic on the basis of fractional inhibitory concentration index (FICI) value of ≤0.5. Furthermore, the activity of Quercitrin and DNJ was evaluated individually and in combination against various cariogenic properties of S. mutans UA159 such as acidogenesis, aciduracity, glucan production, hydrophobicity, biofilm and adherence. Moreover, expression of virulent genes in S. mutans was analysed by quantitative RT- PCR (qRT-PCR) and inhibition of F1F0-ATPase, lactate dehydrogenase and enolase was also evaluated. Finally, scanning electron microscopy (SEM) was used to investigate structural obliteration of biofilm.

RESULTS

The in vitro synergism between Quercitrin and DNJ was observed, with a FICI of 0.313. Their MIC values were found to be 64 μg/ml and 16 μg/ml respectively. The synergistic combination consistently showed best activity against all the virulence factors as compared to Quercitrin and DNJ individually. A reduction in glucan synthesis and biofilm formation was observed at different phases of growth. The qRT-PCR revealed significant downregulation of various virulent genes. Electron micrographs depicted the obliteration of biofilm as compared to control and the activity of cariogenic enzymes was also inhibited.

CONCLUSIONS

The whole study reflects a prospective role of Quercitrin and DNJ in combination as a potent anticariogenic agent against S. mutans.