Trimethylamine N-oxide ameliorates hepatic damage including reduction of hepatic bile acids and cholesterol in Fxr-null mice.

There are conflicting animal experiments on the effect of trimethylamine N-oxide (TMAO), the dietary metabolite, on non-alcoholic fatty liver disease (NAFLD). This study aims to determine the effect of TMAO on NAFLD. A diet containing 0.3% TMAO was fed to farnesoid X receptor (Fxr)-null mice, a model of NAFLD, for 13 weeks. Fxr-null mice fed TMAO showed significant reductions in liver damage markers but not wild-type mice. Hepatic bile acid and cholesterol levels were significantly decreased, and triacylglycerol levels tended to decrease in TMAO-fed Fxr-null mice. Changes in mRNA levels of hepatic bile acid and cholesterol transporters and synthetic enzymes were observed, which could explain the decreased hepatic bile acid and cholesterol levels in Fxr-null mice given the TMAO diet but not in the wild-type mice. These results suggest that TMAO intake ameliorates liver damage in Fxr-null mice, further altering bile acid/cholesterol metabolism in an FXR-independent manner.

The soothing effect of phlorotannins on cedar pollinosis in Cry j 1-stimulated mice.

The antiallergic properties of phlorotannins, algal polyphenols, have been widely reported. This study examined the soothing effect of phlorotannin concentrate (PTC) from Eisenia nipponica on cedar pollinosis in Cry j 1-stimulated mice. PTC reduced the mice's sneezing and nasal rubbing, which was attributed to decreased levels of immunoglobulin E and Th2-type cytokines [interleukin (IL)-4, IL-5, and IL-13].

Histamine elimination by a coupling reaction of fungal amine oxidase and bacterial aldehyde oxidase†.

Histamine (HIST) and other biogenic amines found in fish and fishery products accumulated by the action of bacterial amino acid decarboxylase cannot be decomposed and eliminated by heating or other chemical methods. A simple method for HIST elimination is proposed by a coupling reaction of the fungal amine oxidase (FAO) and bacterial aldehyde oxidase (ALOX) of acetic acid bacteria. As a model reaction, FAO oxidized benzylamine to benzaldehyde, which in turn was oxidized spontaneously to benzoic acid with ALOX. Likely, in HIST elimination, FAO coupled well with ALOX to produce imidazole 4-acetic acid from HIST with an apparent yield of 100%. Imidazole 4-acetaldehyde was not detected in the reaction mixture. In the absence of ALOX, the coupling reaction was incomplete given a number of unidentified substances in the reaction mixture. The proposed coupling enzymatic method may be highly effective to eliminate toxic amines from fish and fishery products.

The Immunomodulating Effect of Phlorotannins from a Brown Alga, Eisenia nipponica, on Mice Stimulated with Ovalbumin through T Cell Regulation.

The immunomodulating effect of phlorotannin was investigated in mice stimulated by ovalbumin. When analyzing the main components of phlorotannin concentrate (PTC) from Eisenia nipponica, seven phlorotannins [eckol, 6,6'-bieckol, 6,8'-bieckol, 8,8'-bieckol, dieckol, phlorofucofuroeckol (PFF)-A, and PFF-B] were detected. These phlorotannins accounted for approximately 80% of PTC. Oral administration of PTC to mice daily for 21 days reduced serum immunoglobulin E (IgE) and total IgG1 levels attributable to Th2 cells. The production of splenic cytokines [interleukin (IL)-10 and transforming growth factor-ß1] and Treg cell-mediated expression of forkhead box protein P3 mRNA were significantly increased whereas the production of inflammatory cytokines (interferon-γ, IL-4, IL-5, and IL-17) by Th1, Th2, and Th17 cells was markedly suppressed. IL-21 production and basic leucine zipper ATF-like transcription factor mRNA expression attributable to follicular helper T (Tfh) cells were also suppressed. Flow cytometric analyses demonstrated increased number of Treg cells despite a decrease in the total T cell population. An increase in total B cells was also observed by the flow cytometric analyses in addition to increases in IL-10 production, which activates B cells. In contrast, the significantly suppressed production of inflammatory cytokines and moderate increase in Treg cell subpopulation indicated a direct impact of PTC on inflammatory lymphocytes (Th1, Th2, Th17, and Tfh). Thus, PTC may exert antiallergic effects by immunomodulation of T cells and inactivation of inflammatory lymphocyte.

Cholesterol-lowering effects of taurine through the reduction of ileal FXR signaling due to the alteration of ileal bile acid composition.

Studies using animal models of hypercholesterolemia have established that taurine reduces cholesterol levels; however, the precise mechanism underlying this cholesterol-lowering effect is unclear. This study addressed this issue by investigating whether bile acid/farnesoid X receptor (FXR) signaling is involved in taurine-mediated cholesterol-lowering effect. Fxr-null and wild-type mice were administered 2% (w/v) taurine in their drinking water and fed a control diet or control diet supplemented with 1% (w/w) cholesterol (cholesterol diet) for 10 days. Taurine intake did not significantly alter hepatic and serum total cholesterol (TC) levels and bile acid compositions of the liver and intestinal lumen in Fxr-null and wild-type mice fed the control diet. By changing to a cholesterol diet, taurine intake significantly decreased hepatic and serum cholesterol levels in wild-type mice. In contrast, it significantly decreased hepatic, not serum, cholesterol levels in Fxr-null mice. Taurine intake significantly altered the bile acid composition of the intestinal lumen in wild-type mice fed a cholesterol diet, but not in Fxr-null mice. An increase in FXR antagonistic bile acids was detected in the intestinal lumen of taurine-treated wild-type mice fed a cholesterol diet. Taurine intake reduced the ileal expression of FXR target genes fibroblast growth factor 15 (Fgf15) and small heterodimer partner (Shp). In contrast, it enhanced the hepatic expression of cholesterol 7α-hydroxylase (Cyp7a1) in wild-type mice fed a cholesterol diet, but not in Fxr-null mice. These results suggest that taurine is partially involved in cholesterol lowering by reducing the ileal FXR signaling due to the alteration of ileal bile acid composition.

Dieckol isolated from a brown alga, Eisenia nipponica, suppresses ear swelling from allergic inflammation in mouse.

We previously found a lipophilic fraction of the methanol/chloroform extract of a brown alga, Eisenia nipponica, that had an antiallergic effect in a murine ear swelling test. In this study, we purified the active component from the lipophilic fraction using high performance liquid chromatography and analyzed the mass and nuclear magnetic resonance spectra. This uncovered the phlorotannin dieckol, which exhibited antiallergic effects in an ear swelling test using mice sensitized by arachidonic acid, 12-O-tetradecanoylphorbol-13-acetate, and oxazolone. Mechanistic investigations indicated that dieckol suppressed degranulation, chemical mediator release, and the expression of mRNA such as cyclooxygenase-2, interleukin-6, and tumor necrosis factor-α in rat basophilic leukemia-2H3 cells. In summary, we isolated dieckol from E. nipponica and demonstrated its antiallergic mechanisms. PRACTICAL APPLICATIONS: As the incidence of allergies increases worldwide, so too does the demand for food components with antiallergic and anti-inflammatory properties. Given this trend, we focused on a brown alga that displays a variety of bioactivities. Here, we have isolated dieckol from the antiallergic lipophilic fraction of E. nipponica and found that it possesses diverse physiological activities that may prevent lifestyle-related diseases. Consequently, dieckol or the alga containing this phlorotannin could be used as a health food ingredient to combat not only allergies, but also variety of disorders including the undesirable effects of aging.

Selenoneine Ameliorates Hepatocellular Injury and Hepatic Steatosis in a Mouse Model of NAFLD.

Selenoneine is a novel organic selenium compound markedly found in the blood, muscles, and other tissues of fish. This study aimed to determine whether selenoneine attenuates hepatocellular injury and hepatic steatosis in a mouse model of non-alcoholic fatty liver disease (NAFLD). Mice lacking farnesoid X receptor (FXR) were used as a model for fatty liver disease, because they exhibited hepatomegaly, hepatic steatosis, and hepatic inflammation. Fxr-null mice were fed a 0.3 mg Se/kg selenoneine-containing diet for four months. Significant decreases in the levels of hepatomegaly, hepatic damage-associated diagnostic markers, hepatic triglycerides, and total bile acids were found in Fxr-null mice fed with a selenoneine-rich diet. Hepatic and blood clot total selenium concentrations were 1.7 and 1.9 times higher in the selenoneine group than in the control group. A marked accumulation of selenoneine was found in the liver and blood clot of the selenoneine group. The expression levels of oxidative stress-related genes (heme oxygenase 1 (Hmox1), glutathione S-transferase alpha 1 (Gsta1), and Gsta2), fatty acid synthetic genes (stearoyl CoA desaturase 1(Scd1) and acetyl-CoA carboxylase 1 (Acc1)), and selenoprotein (glutathione peroxidase 1 (Gpx1) and selenoprotein P (Selenop)) were significantly decreased in the selenoneine group. These results suggest that selenoneine attenuates hepatic steatosis and hepatocellular injury in an NAFLD mouse model.

Taurine attenuates hepatic steatosis in a genetic model of fatty liver disease.

Mice lacking the farnesoid X receptor (FXR) are used as a genetic model for nonalcoholic fatty liver disease because their livers exhibit hepatic steatosis and inflammation. The influence of taurine drinking on disrupted hepatic function was investigated using female Fxr-null mice. Significant decreases in the levels of hepatic damage-associated diagnostic markers, hepatic triglycerides, non-esterified fatty acids, and total bile acids were found in Fxr-null mice that had drunk water containing 0.5% taurine for four weeks. Hepatic but not serum taurine concentrations were significantly increased in these mice. The expression levels of oxidative stress-related genes (Hmox1 and Gsta1) and fatty acid synthetic genes (Acc1 and Scd1) were significantly decreased in these mice. These results suggest that drinking taurine improves hepatic steatosis and dysfunction caused by a lack of FXR.

Orally Administered Phlorotannins from Eisenia arborea Suppress Chemical Mediator Release and Cyclooxygenase-2 Signaling to Alleviate Mouse Ear Swelling.

Phlorotannin is the collective term for polyphenols derived from brown algae belonging to the genera Ascopyllum, Ecklonia, Eisenia, Fucus and Sargassum etc. Since the incidence of allergies is currently increasing in the world, there is a focus on phlorotannins having anti-allergic and anti-inflammatory effects. In this study, six purified phlorotannins (eckol; 6,6'-bieckol; 6,8'-bieckol; 8,8'-bieckol; phlorofucofuroeckol (PFF)-A and PFF-B) from Eisenia arborea, orally administered to mice, were examined for their suppression effects on ear swelling. In considering the suppression, we also examined whether the phlorotannins suppressed release of chemical mediators (histamine, leukotriene B4 and prostaglandin E2), and mRNA expression and/or the activity of cyclooxygenase-2 (COX-2), using RBL-2H3 cells, a cultured mast cell model. Results showed that the phlorotnannins exhibited suppression effects in all experiments, with 6,8'-bieckol, 8,8'-bieckol and PFF-A showing the strongest of these effects. In conclusion, orally administered phlorotannins suppress mouse ear swelling, and this mechanism apparently involves suppression of chemical mediator release and COX-2 mRNA expression or activity. This is the first report of the anti-allergic effects of the orally administered purified phlorotannins in vivo. Phlorotannins show potential for use in functional foods or drugs.

Fish oil feeding reverses hepatomegaly and disrupted hepatic function due to the lack of FXR signaling.

Mice lacking farnesoid X receptor (FXR) are used as a model for nonalcoholic fatty liver disease because their livers exhibit hepatomegaly, hepatic steatosis, and hepatic inflammation. The influence of fish oil feeding on hepatomegaly and disrupted hepatic function was investigated using female Fxr-null mice and wild-type mice fed a fish oil diet (2% fish oil and 2% corn oil) or a control diet (4% corn oil) for 4 weeks. Hepatic n-3 polyunsaturated fatty acid (PUFA) levels, including 22:6 n-3 docosahexaenoic acid (DHA) and 20:5 n-3 eicosapentaenoic acid (EPA) were significantly higher in the fish oil group than those in the control group of Fxr-null mice and wild-type mice. Fxr-null mouse livers of the control group showed a whitish brown coloration, whereas Fxr-null mouse livers of the fish oil group showed a dark brown coloration similar to that of wild-type mice. The liver in Fxr-null mice of the fish oil group was smaller than that of the control group. There was a significant decrease in the levels of hepatic damage-associated diagnostic markers, hepatic and serum bile acids, triglycerides, free fatty acids, and total cholesterol levels in Fxr-null mice because of fish oil feeding. It also reversed elevated mRNA levels of oxidative stress-related genes (Hmox1, Gsta1, and Gsta2) and reduced mRNA levels of transcriptional factors (Pparα and Shp) in Fxr-null mice. These results suggest that fish oil feeding reverses hepatomegaly and disrupted hepatic function due to the lack of FXR signaling.

Relationship between 4-hydroxy-2-hexenal contents and commercial grade by organoleptic judgement in Japanese dried laver Porphyra spp.

To evaluate the correlation between the commercial grade determined by organoleptic judgment panel and chemical substances in dried laver Porphyra spp., we analyzed the contents of free amino acids, 5'-nucleotides, total lipids, fatty acids, α-tocopherol, lipophilic pigments, and aldehydes in several grades of laver that had been classified by an organoleptic judgment panel. Compared with the lower-grade laver samples, the excellent-grade laver samples contained higher concentrations of free amino acids, 5'-nucleotides, total lipids, α-tocopherol, chlorophyll a, and ß-carotene and lower concentrations of aldehydes such as 4-hydroxy-2-hexenal (HHE), propanal, butanal, and 1-hexanal, which are formed during lipid peroxidation of n-3 or n-6 polyunsaturated fatty acids. In addition, the HHE content was strongly correlated with the propanal content in the analyzed laver (r(2)=0.9123). These results showed that the commercial grade assigned by an organoleptic judgment panel was correlated with chemical substances associated with color, taste, and the prevention of lipid oxidation.

Relationship between the risk for a shrimp allergy and freshness or cooking.

Tropomyosins are defined as risk factors for shrimp allergy. However, their concentration in different preparations has not been clarified. We quantified the tropomyosin concentration in shrimp meat, which was cooked using several methods or was stored under various conditions. The results demonstrated that shrimp meat from various preparations and storage conditions maintained tropomyosin concentrations that were sufficient to cause food allergies.

Accumulation of hydroxyl lipids and 4-hydroxy-2-hexenal in live fish infected with fish diseases.

Hydroxy lipids (L-OH) and 4-hydroxy-2-hexenal (HHE) levels as well as other parameters such as lipid level, lipid class, fatty acid composition, and other aldehydes levels in the liver of diseased fish were investigated. Although significant differences in lipid level, lipid class, fatty acid composition, and other aldehyde levels were not always observed between normal and diseased fish, L-OH and HHE levels were significantly higher in the liver of the diseased fish than in that of the normal fish cultured with the same feeds under the same conditions. In the liver of puffer fish (Fugu rubripes) infected with Trichodina, L-OH and HHE levels significantly increased from 25.29±5.04 to 47.70 ± 5.27 nmol/mg lipid and from 299.79±25.25 to 1,184.40±60.27 nmol/g tissue, respectively. When the levels of HHE and other aldehydes in the liver of the normal and diseased puffer fish were plotted, a linear relationship with a high correlation coefficient was observed between HHE and propanal (r2=0.9447). Increased L-OH and HHE levels in the liver of the diseased fish and a high correlation between HHE and propanal in the liver of the normal and diseased fish were also observed in flat fish (Paralichthys olivaceus) infected with streptococcus, yellowtail (Seriola quinqueradiata) infected with jaundice, and amberjack (S. purpurascens) infected with Photobacterium damselae subsp. piscicida.

Isolation of a new anti-allergic phlorotannin, phlorofucofuroeckol-B, from an edible brown alga, Eisenia arborea.

Eisenia arborea is an edible brown alga occasionally used as a folk medicine in gynecopathy in Japan. A new phlorotannin was isolated from the alga during our search for naturally occurring anti-allergic compounds from edible algae guided by the inhibitory effect on histamine release from rat basophile leukemia (RBL)-2H3 cells. The phlorotannin was called "phlorofucofuroeckol-B." Its structure was determined by spectral analysis and chemical conversion. This paper describes the isolation, structure elucidation, and inhibitory effect of phlorofucofuroeckol-B on histamine release.

IEC-6 intestinal cell death induced by bovine milk alpha-lactalbumin.

Potent inhibition of cell proliferation was found for commercial preparations of bovine alpha-lactalbumin on cultured intestinal cell line IEC-6 albeit lot-dependent. The inhibition was irreversible and a single exposure to the culture medium containing alpha-lactalbumin of an active lot for a period as short as 30 min was enough to provoke cell death, possibly through apoptosis. The oligomer fraction from size exclusion chromatography was significantly robust, while the monomer fraction remained totally inert, in inducing cell death. Incubation at 37 degrees C for 5 d with 30% trifluoroethanol in acetate, pH 5.5, in a slowly rotating test tube rendered the monomer fraction cytotoxic. Again, the resulting inhibitory activity was found in the oligomer fraction from size exclusion chromatography, with emergence of subtle peaks at 22- and 30-kDa. Furthermore, the occurrence of SDS-stable 30-kDa as well as 20-kDa bands on electrophoresis was a common feature for alpha-lactalbumin with the activity inducing cell death. Thus, a certain dimeric state can be implicated in the cytotoxicity of bovine alpha-lactalbumin.

Involvement of SDS-stable higher M(r) forms of bovine normal milk alpha-lactalbumin in inducing intestinal IEC-6 cell death.

Monomeric 14-kDa bovine alpha-lactalbumin was purified with a preparation of lower molecular weight whey protein concentrate from Holstein cow normal milk followed by size exclusion chromatography. The protein showed a stimulatory rather than an inhibitory effect on the proliferation of a cultured IEC-6 cell line from the rat small intestine. But incubation in 30% trifluoroethanol/acetate buffer (pH 5.5) at 37 degrees C for 5 d in a slowly rotating test tube rendered it highly cytotoxic with concomitant appearance of SDS-stable 20- and 30-kDa forms of alpha-lactalbumin on electrophoresis. Furthermore, alpha-lactalbumin obtained by a one-step purification procedure by affinity chromatography on an anti-alpha-lactalbumin antibody column from the lower molecular weight whey protein concentrate, which had been found to contain several SDS-stable higher M(r) forms of alpha-lactalbumin, exhibited potent inhibitory activity on IEC-6 cell growth. These results indicate the involvement of SDS-stable higher M(r) forms of bovine normal milk alpha-lactalbumin in inducing cell death on the intestinal IEC-6 cell line.