Transport Form and Pathway from the Intestine to the Peripheral Tissues and the Intestinal Absorption and Metabolism Properties of Oleamide.

This study aimed to obtain information on the transport form and pathway from the intestine to the peripheral tissues and on the intestinal absorption and metabolism properties of oleamide (cis-9-octadecenamide). Oleamide was primarily transported via the portal vein. Density gradient centrifugation indicated that plasma oleamide was enriched in the fractions containing albumin in the portal and peripheral blood. Oleamide formed a complex with albumin in an endothermic reaction (apparent Kd = 4.4 µM). The CD36 inhibitor inhibited the oleamide uptake into the intestinal epithelial Caco-2 cells, and oleamide decreased the cell surface CD36 level. The fatty acid amide hydrolase (FAAH) inhibitor increased the transepithelial transport of oleamide across Caco-2 cells and the plasma oleamide concentration in mice intragastrically administered with oleamide. These results indicate that oleamide is transported primarily via the portal vein as a complex with albumin. Furthermore, we suggest that oleamide is taken up via CD36 in the small intestine and degraded intracellularly by FAAH.

Dietary oleamide attenuates obesity induced by housing mice in small cages.

Physical inactivity due to prolonged sedentary behavior induces obesity. Therefore, we investigated whether housing mice in small cages to mimic sedentary behavior induced obesity and whether dietary oleamide (cis-9,10-octadeceneamide) suppressed the induced obesity. A single oral administration of oleamide (50 mg/kg) to mice resulted in the accumulation of the exogenous oleamide in abdominal visceral fat. Next, mice were housed in small cages and oleamide (50 mg/kg/d) was orally administered for 12 weeks. Housing mice in small cages impaired glucose tolerance and increased food efficiency. It also increased body weight and abdominal fat mass. Dietary oleamide improved the impairment and inhibited their increase in mice housed in small cages. Furthermore, dietary oleamide suppressed the mRNA expression of inflammation-related factors in the abdominal fat of mice housed in small cages. Hence, these results indicate that although housing mice in small cages induces obesity and increases abdominal fat mass, dietary oleamide suppresses the obesity.

Oleamide rescues tibialis anterior muscle atrophy of mice housed in small cages.

Skeletal muscle atrophy causes decreased physical activity and increased risk of metabolic diseases. We investigated the effects of oleamide (cis-9,10-octadecanamide) treatment on skeletal muscle health. The plasma concentration of endogenous oleamide was approximately 30 nm in male ddY mice under normal physiological conditions. When the stable isotope-labelled oleamide was orally administered to male ddY mice (50 mg/kg), the plasma concentration of exogenous oleamide reached approximately 170 nm after 1 h. Male ddY mice were housed in small cages (one-sixth of normal size) to enforce sedentary behaviour and orally administered oleamide (50 mg/kg per d) for 4 weeks. Housing in small cages decreased tibialis anterior (TA) muscle mass and the cross-sectional area of the myofibres in TA muscle. Dietary oleamide alleviated the decreases in TA muscle and resulted in plasma oleamide concentration of approximately 120 nm in mice housed in small cages. Housing in small cages had no influence on the phosphorylation levels of Akt serine/threonine kinase (Akt), mechanistic target of rapamycin (mTOR) and ribosomal protein S6 kinase (p70S6K) in TA muscle; nevertheless, oleamide increased the phosphorylation levels of the proteins. Housing in small cages increased the expression of microtubule-associated protein 1 light chain 3 (LC3)-II and sequestosome 1 (p62), but not LC3-I, in TA muscle, and oleamide reduced LC3-I, LC3-II and p62 expression levels. In C2C12 myotubes, oleamide increased myotube diameter at ≥100 nm. Furthermore, the mTOR inhibitor, Torin 1, suppressed oleamide-induced increases in myotube diameter and protein synthesis. These results indicate that dietary oleamide rescued TA muscle atrophy in mice housed in small cages, possibly by activating the phosphoinositide 3-kinase/Akt/mTOR signalling pathway and restoring autophagy flux.

Oenothein B in Eucalyptus Leaf Extract Suppresses Fructose Absorption in Caco-2 Cells.

Inhibition of fructose absorption may suppress adiposity and adiposity-related diseases caused by fructose ingestion. Eucalyptus leaf extract (ELE) inhibits intestinal fructose absorption (but not glucose absorption); however, its active compound has not yet been identified. Therefore, we evaluated the inhibitory activity of ELE obtained from Eucalyptus globulus using an intestinal fructose permeation assay with the human intestinal epithelial cell line Caco-2. The luminal sides of a cell monolayer model cultured on membrane filters were exposed to fructose with or without the ELE. Cellular fructose permeation was evaluated by measuring the fructose concentration in the medium on the basolateral side. ELE inhibited 65% of fructose absorption at a final concentration of 1 mg/mL. Oenothein B isolated from the ELE strongly inhibited fructose absorption; the inhibition rate was 63% at a final concentration of 5 µg/mL. Oenothein B did not affect glucose absorption. In contrast, the other major constituents (i.e., gallic acid and ellagic acid) showed little fructose-inhibitory activity. To our knowledge, this is the first report that oenothein B in ELE strongly inhibits fructose absorption in vitro. ELE containing oenothein B can prevent and ameliorate obesity and other diseases caused by dietary fructose consumption.

Effects of low ethanol consumption on nonalcoholic steatohepatitis in mice.

Several recent clinical and epidemiological studies have suggested inhibitory effects of light-to-moderate alcohol consumption on nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH); however, these effects have not been confirmed in experimental studies. Therefore, in this study, we examined the effects of small amounts of ethanol consumption on a mouse model of NASH. Nine-week-old male obese mice (db/db mice) were divided into the following groups: control, high-fat, and low-ethanol groups. The control group was provided ad libitum access to a control liquid diet, the high-fat group was provided access to a high-fat liquid diet, and the low-ethanol group was provided access to the high-fat liquid diet supplemented with 0.1% (w/w) ethanol. Eight weeks later, the mice were sacrificed and serum biochemical, histopathological, and molecular analyses were performed. Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels were significantly lower in the low-ethanol group than in the high-fat group (p = 0.033 and 0.037, respectively). Liver histopathological analysis showed that intralobular and portal inflammation was significantly milder in the low-ethanol group than in the high-fat group (p = 0.018 and 0.041, respectively). However, no significant differences were observed among the groups in serum insulin and adiponectin levels, hepatic 4-hydroxynonenal (oxidative injury marker) levels, and hepatic cytokine and receptor gene expression levels. In conclusion, the serum transaminase levels and hepatic inflammation in NASH model mice improved after administration of small amounts of ethanol. This study directly demonstrated inhibitory effects of small amounts of ethanol on NASH in mice. The mechanisms underlying these inhibitory effects remain to be elucidated.

Bone Growth is Influenced by Fructose in Adolescent Male Mice Lacking Ketohexokinase (KHK).

Fructose is metabolized in the cytoplasm by the enzyme ketohexokinase (KHK), and excessive consumption may affect bone health. Previous work in calcium-restricted, growing mice demonstrated that fructose disrupted intestinal calcium transport. Thus, we hypothesized that the observed effects on bone were dependent on fructose metabolism and took advantage of a KHK knockout (KO) model to assess direct effects of high plasma fructose on the long bones of growing mice. Four groups (n = 12) of 4-week-old, male, C57Bl/6 background, congenic mice with intact KHK (wild-type, WT) or global knockout of both isoforms of KHK-A/C (KHK-KO), were fed 20% glucose (control diet) or fructose for 8 weeks. Dietary fructose increased by 40-fold plasma fructose in KHK-KO compared to the other three groups (p < 0.05). Obesity (no differences in epididymal fat or body weight) or altered insulin was not observed in either genotype. The femurs of KHK-KO mice with the highest levels of plasma fructose were shorter (2%). Surprisingly, despite the long-term blockade of KHK, fructose feeding resulted in greater bone mineral density, percent volume, and number of trabeculae as measured by µCT in the distal femur of KHK-KO. Moreover, higher plasma fructose concentrations correlated with greater trabecular bone volume, greater work-to-fracture in three-point bending of the femur mid-shaft, and greater plasma sclerostin. Since the metabolism of fructose is severely inhibited in the KHK-KO condition, our data suggest mechanism(s) that alter bone growth may be related to the plasma concentration of fructose.

Hyperthermic Effect of Ginger (Zingiber officinale) Extract-Containing Beverage on Peripheral Skin Surface Temperature in Women.

Ginger is known to warm the body. Therefore, we conducted a placebo-controlled crossover trial to investigate the hyperthermic effect of a palatable ginger-containing beverage in healthy women with cold-sensitive extremities. Six women drank 280 mL of 0.07% ginger extract-containing or placebo beverage in a temperature-controlled room (21°C). Their palm temperatures were measured as measure of surface body temperature using a thermographic camera before intake and every 10 min after intake for 60 min. Palm temperature increased immediately following intake of the ginger and placebo beverages. However, palm temperature following intake of the ginger beverage increased for 20 min, while palm temperature following placebo intake decreased again after 10 min. The increased palm temperature following ginger intake was maintained significantly longer than after placebo intake (p < 0.05). In response to a questionnaire, some subjects answered that their increased body temperature was maintained after drinking the ginger beverage. Ginger extract-containing beverage may thus improve cold sensitivity.

Sequential Synthesis, Olfactory Properties, and Biological Activity of Quinoxaline Derivatives.

A simple, practical, and rapid access to quinoxalin-2-ones 1, 1,2,3,4-tetrahydroquinoxalines 2, quinoxalines 3, and quinoxalin-2(1H)-ones 4 has been achieved, based on the copper-catalyzed quinoxalinone formation of 2-haloanilines and amino acids followed by their reduction and oxidation. The olfactory properties and lipid accumulation inhibitory activity in cultured hepatocytes of the quinoxaline derivatives were also evaluated.

Inhibitory effects of geranium essential oil and its major component, citronellol, on degranulation and cytokine production by mast cells.

We investigated the effects of geranium essential oil (GEO) on anaphylaxis. GEO can exert antioxidant and anti-inflammatory effects, but its roles in allergic reactions are incompletely understood. Here, we used mouse cells to show that GEO inhibited the degranulation of cultured mast cells (CMCs). Citronellol is the major component of GEO and inhibited CMC degranulation. The l-enantiomer of citronellol more effectively suppressed CMC degranulation than did d-citronellol. We also examined whether citronellol could inhibit the immunoglobulin (Ig) E-induced production of tumor necrosis factor (TNF)-α. Treatment with various concentrations of citronellol before CMC activation with IgE significantly inhibited the induction of TNF-α in a dose-dependent manner. Mechanistically, citronellol suppressed the phosphorylation of mitogen-activated protein kinase (ERK), which is critical for ERK activation and the production of inflammatory cytokines in mast cells. These findings suggest that citronellol may represent a candidate compound for the effective treatment of allergic diseases.

Effect of dietary fructose on portal and systemic serum fructose levels in rats and in KHK-/- and GLUT5-/- mice.

Elevated blood fructose concentrations constitute the basis for organ dysfunction in fructose-induced metabolic syndrome. We hypothesized that diet-induced changes in blood fructose concentrations are regulated by ketohexokinase (KHK) and the fructose transporter GLUT5. Portal and systemic fructose concentrations determined by HPLC in wild-type mice fed for 7 days 0% free fructose were <0.07 mM, were independent of time after feeding, were similar to those of GLUT5(-/-), and did not lead to hyperglycemia. Postprandial fructose levels, however, increased markedly in those fed isocaloric 20% fructose, causing significant hyperglycemia. Deletion of KHK prevented fructose-induced hyperglycemia, but caused dramatic hyperfructosemia (>1 mM) with reversed portal to systemic gradients. Systemic fructose in wild-type and KHK(-/-) mice changed by 0.34 and 1.8 mM, respectively, for every millimolar increase in portal fructose concentration. Systemic glucose varied strongly with systemic, but not portal, fructose levels in wild-type, and was independent of systemic and portal fructose in KHK(-/-), mice. With ad libitum feeding for 12 wk, fructose-induced hyperglycemia in wild-type, but not hyperfructosemia in KHK(-/-) mice, increased HbA1c concentrations. Increasing dietary fructose to 40% intensified the hyperfructosemia of KHK(-/-) and the fructose-induced hyperglycemia of wild-type mice. Fructose perfusion or feeding in rats also caused duration- and dose-dependent hyperfructosemia and hyperglycemia. Significant levels of blood fructose are maintained independent of dietary fructose, KHK, and GLUT5, probably by endogenous synthesis of fructose. KHK prevents hyperfructosemia and fructose-induced hyperglycemia that would markedly increase HbA1c levels. These findings explain the hyperfructosemia of human hereditary fructosuria as well as the hyperglycemia of fructose-induced metabolic syndrome.

Inhibitory effects of eucalyptus and banaba leaf extracts on nonalcoholic steatohepatitis induced by a high-fructose/high-glucose diet in rats.

Nonalcoholic steatohepatitis (NASH) is a liver disease associated with metabolic syndrome. The aim of this work was to examine whether eucalyptus (Eucalyptus globulus) leaf extract (ELE) and banaba (Lagerstroemia speciosa L.) leaf extract (BLE) inhibited NASH induced by excessive ingestion of fructose in rats. Wistar rats were divided into four groups according to four distinct diets: starch diet (ST), high-fructose/high-glucose diet (FG), FG diet supplemented with ELE, or FG diet supplemented with BLE. All rats were killed after 5 weeks of treatment. Serum alanine aminotransferase and total cholesterol levels were significantly lower in the BLE group than in the FG group. Liver histopathology, including steatosis, lipogranulomas, and perisinusoidal fibrosis, was significantly attenuated in the ELE and BLE groups compared with the FG group. Levels of 2-thiobarbituric acid reactive substances (TBARS), which reflect oxidative injury to the liver, were significantly suppressed by ELE and BLE. Western blotting analysis indicated that interleukin-6 expression levels were significantly lower in the ELE and BLE groups than in the FG group. These results suggest that ELE and BLE reduced lipogenesis, oxidative stress, and inflammatory cytokine expression and thus inhibited NASH induced by excessive ingestion of fructose in rats.

Current pharmacological therapies for nonalcoholic fatty liver disease/nonalcoholic steatohepatitis.

Nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH) is considered to be a hepatic manifestation of metabolic syndrome, and its incidence is rapidly increasing worldwide. It is currently the most common chronic liver disease. NASH can progress to liver cirrhosis and hepatocellular carcinoma, and may result in liver-related death. Currently, the principal treatment for NAFLD/NASH is lifestyle modification by diet and exercise. However, pharmacological therapy is indispensable because obese patients with NAFLD often have difficulty maintaining improved lifestyles. The pathogenesis of NAFLD/NASH has not been completely elucidated. However, insulin resistance, inflammatory cytokines, and oxidative stress are thought to be important in the development and/or progression of the disease. Currently, insulin sensitizers (thiazolidinediones) and antioxidants (vitamin E) seem to be the most promising therapeutic agents for NAFLD/NASH, and lipid-lowering drugs, pentoxifylline, angiotensin receptor blockers, and n-3 polyunsaturated fatty acids also have promise. However, there is a lack of consensus regarding the most effective and appropriate pharmacotherapy for NAFLD/NASH. Animal experiments suggest that herbal medicines and natural products may be promising therapeutic agents for NAFLD/NASH, but their efficacy and safety are yet to be investigated in human studies. In this paper, we review the existing and potential pharmacological therapies for NAFLD/NASH.

Suppression of allergic and inflammatory responses by essential oils derived from herbal plants and citrus fruits.

The aim of the present study was to investigate the biological activity of 20 essential oils (EOs) derived from herbal plants and citrus fruits. The in vitro anti-allergic and anti-inflammatory activities of these oils were investigated, and the EO which was found to have the strongest activity of the 20 EOs examined, was investigated further to identify its components and bioactive compounds. The in vitro anti-allergic activity was determined by measuring the release of ß-hexosaminidase from rat basophilic leukemia (RBL-2H3) cells treated with the calcium ionophore, A23187. The in vitro anti-inflammatory activity was determined by measuring the production of tumor necrosis factor-α (TNF-α) in RAW264.7 murine macrophages treated with lipopolysaccharide. Among the EOs examined, lemongrass [Cymbopogon citratus (DC.) Stapf] elicited the strongest anti-allergic and anti-inflammatory effects. A principal component of this EO is citral (3,7-dimethyl-2,6-octadien-1-al) (74.5%), a mixture of the stereoisomers, geranial (trans-citral, 40.16%) and neral (cis-citral, 34.24%), as determined by chromatography-mass spectrometry analysis. The activities of citral and geranial are similar to those of lemongrass EO. These compounds elicited significant in vivo anti-allergic and anti-inflammatory effects, suppressing an immunoglobulin E (IgE)-induced passive cutaneous anaphylactic reaction in mice and a 12-O-tetradecanoylphorbol-13-acetate-induced inflammatory mouse ear edema, respectively. Our data demonstrate that lemongrass EO and its constituents, citral and geranial, may be a therapeutic candidate for allergic and inflammatory diseases.

Effects of essential oils from herbal plants and citrus fruits on DNA polymerase inhibitory, cancer cell growth inhibitory, antiallergic, and antioxidant activities.

In this study, the biological activity of 20 essential oils (EOs) from herbal plants and citrus fruits were investigated in terms of mammalian DNA polymerase (pol) inhibitory activity, cancer cell (human colon carcinoma, HCT116) growth inhibitory activity, antiallergic activity, as anti-ß-hexosaminidase release activity in rat basophilic leukemia RBL-2H3 cells treated with calcium ionophore A23187, and antioxidant activity by a lipophilic-oxygen radical absorbance capacity method. These EOs showed patterns of inhibition of pol α, a DNA replicative pol, similar to their cancer cell growth inhibitory activity, and their inhibitory activity on pol λ, a DNA repair/recombination pol, by the EOs showed correlation with anti-ß-hexosaminidase release activity. Among these EOs, chamomile (Matricaria chamomilla L.) was the strongest inhibitor of pols α and λ and showed significant effects on both cancer cell growth and mast cell degranulation. On the basis of these results, chamomile EO can be recommended as a potentially useful, bioactive candidate for therapeutic applications.

Eucalyptus leaf extract suppresses the postprandial elevation of portal, cardiac and peripheral fructose concentrations after sucrose ingestion in rats.

Overintake of sucrose or fructose induces adiposity. Fructose undergoes a strong Maillard reaction, which worsens diabetic complications. To determine whether Eucalyptus globulus leaf extract (ELE) suppresses the postprandial elevation of serum fructose concentrations (SFCs) in the portal, cardiac, and peripheral blood after sucrose ingestion, we performed gas chromatography/mass spectrometry (GC/MS) and measured SFC without any interference by contaminating glucose in the samples. Fasting Wistar rats were orally administered water (control group) or ELE (ELE group) before sucrose ingestion. Blood was collected from the portal vein, heart, and tail. The increase in the SFCs in the portal and cardiac samples 30 min after sucrose ingestion was lower in the ELE group than in the control group. The coefficient of correlation between the SFCs in the portal and cardiac samples was 0.825. The peripheral SFC in the control group progressively increased and was 146 micromol/L at 60 min. This increase was significantly lower in the ELE group. In contrast, the serum glucose concentrations in the 2 groups were similar. ELE suppressed postprandial hyperfructosemia in the portal, cardiac, and peripheral circulations. ELE may counteract glycation caused by high blood fructose concentrations induced by the consumption of fructose-containing foods or drinks.

Inhibitive effects of alkyl gallates on hyaluronidase and collagenase.

A series of the gallate esters of n-alkanols (C(1)-C(12)) was examined to determine their inhibitory activities against hyaluronidase and collagenase. Hexyl, heptyl, octyl, nonyl, and decyl gallates inhibited both hyaluronidase and collagenase, and the most potent inhibitor was octyl gallate against both enzymes. Octyl 3,5-dihydroxybenzoate showed inhibitory effects on hyaluronidase, whereas collagenase was inhibited by octyl 3,4-dihydroxybenzoate.

Rats fed fructose-enriched diets have characteristics of nonalcoholic hepatic steatosis.

Nonalcoholic steatohepatitis (NASH) and nonalcoholic fatty liver disease are increasing in adults and are likely to be increasing in children. Both conditions are hepatic manifestations of metabolic syndrome. Experimental animals fed fructose-enriched diets are widely recognized as good models for metabolic syndrome. However, few reports have described the hepatic pathology of these experimental animals. In this study, 5-wk-old Wistar specific pathogen-free rats, which are a normal strain, were fed experimental diets for 5 wk. We then evaluated the degree of steatohepatitis. The 5 diet groups were as follows: cornstarch (70% wt:wt) [control (C)], high-fructose (70%) (HFr), high-sucrose (70%) (HS), high-fat (15%) (HF), and high-fat (15%) high-fructose (50%) (HFHFr) diets. The macrovesicular steatosis grade, liver:body weight ratio, and hepatic triglyceride concentration were significantly higher in the HFr group than in the other 4 groups. However, the HFr group had a significantly lower ratio of epididymal white fat:body weight than the other 4 groups and had a lower final body weight than the HF and HFHFr groups. The HF group had a greater final body weight than the C, HFr, and HS groups, but no macrovesicular steatosis was observed. The HFr group had a significantly higher grade of lobular inflammation than the other 4 groups. The distribution of lobular inflammation was predominant over portal inflammation, which is consistent with human NASH. In conclusion, rats fed fructose-enriched diets are a better model for NASH than rats fed fat-enriched diets.

Inhibitory effects of guarana seed extract on passive cutaneous anaphylaxis and mast cell degranulation.

This study investigated the effects of guarana seed extract (GSE) on an anti-allergic mechanism. GSE orally administered inhibited the anti-dinitrophenol IgE-induced passive cutaneous anaphylaxis reaction in mice. Furthermore, it inhibited the degranulation of rat basophilic leukemia RBL-2H3 cells. It had no cytotoxicity on RBL-2H3 cells. These results show that GSE is a candidate for effective therapeutic material for allergic diseases.

Eucalyptus leaf extract inhibits intestinal fructose absorption, and suppresses adiposity due to dietary sucrose in rats.

Sucrose is more lipogenic than starch, and the extreme ingestion of sucrose induces adiposity and obesity. The aim of this study was to examine the effect of the eucalyptus (Eucalyptus globulus) leaf extract (ELE) on adiposity due to dietary sucrose in rats. In addition, in this study, the effect of ELE on intestinal fructose absorption was also examined. Rats were fed a high-sucrose diet (75 % in calorie base) with or without ELE (10 g/kg diet) for 5 weeks. Body weight was lower in the rats receiving ELE than in the controls (342 (sd 37.9) v. 392 (sd 26.0) g (n 7); P<0.05). Furthermore, ELE resulted in decreases in the triacylglycerol concentrations in the plasma (1.44 (sd 0.448) v. 2.79 (sd 0.677) mmol/l (n 7); P<0.05) and liver (19.1 (sd 5.07) v. 44.1 (sd 16.28) micromol/g (n 7); P<0.05). In contrast, ELE did not show any significant effects in the rats fed a starch diet. When rats were orally given ELE 10 min before fructose administration, the intestinal fructose absorption, which was examined by measuring the elevated concentration of fructose in the portal vein at 30 min after the fructose administration, was significantly inhibited in a dose-dependent manner. Furthermore, in rats fed a high-fructose diet, the plasma and hepatic triacylglycerol concentrations were significantly decreased by ELE. These results indicate that ELE, which inhibits the intestinal fructose absorption, can suppress adiposity in rats that ingest large amounts of sucrose or fructose.