Yoshimasa Sugiura

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.

Inhibitory effects of seaweeds on histamine release from rat basophile leukemia cells (RBL-2H3)

The effects of 80% methanol extracts from frozen samples of 41 macroalgae and one sea grass collected in the Ise-Shima region of Japan were investigated on histamine release from rat basophile leukemia cells (RBL-2H3) sensitized with antidinitrophenyl (DNP) IgE and stimulated with DNP-BSA. Of the 21 brown algae, five green and 15 red algae, and one sea grass tested, only extracts from seven brown algae suppressed histamine release from RBL cells, as determined by highperformance liquid chromatography (HPLC) analysis. When the cytotoxic effects of the seven brown algal extracts were investigated by Trypan blue staining, only Eisenia arborea and Sargassum thunbergil did not show cytotoxic effects. Therefore, we conclude that E. arborea and S. thunbergii may contain compounds that have antiallergic effects without inducing cell death.

Anti-allergic effects of the brown alga Eisenia arborea on Brown Norway rats

To investigate the anti-allergic effects of the brown alga Eisenia arborea. A strain of Brown Norway rats know to strongly respond to immunoglobulin E (IgE) were used as an allergy model animal. The rats were immunized with ovalbumin by oral administration. The levels of serum IgE and histamine were suppressed in the rats fed a diet supplemented with dried E. arborea powder. As for the cytokine pattern, the interferon-γ production in the spleens and mesenteric lymph nodes (MLN) was enhanced, and the interleukin-4 (IL-4) production in the spleens and/or IL-10 production in the spleens and MLN were suppressed. These results, together with the change in the Th1/Th2 balance, indicate that the rats fed with E. arborea became more anti-allergic, suggesting that E. arborea might possess anti-allergic effects.

SIMULTANEOUS IDENTIFICATION OF 4-HYDROXY-2-HEXENAL AND 4-HYDROXY-2-NONENAL IN FOODS BY PRE-COLUMN FLUORIGENIC LABELING WITH 1,3-CYCLOHEXANEDIONE AND REVERSED-PHASE HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY WITH FLUORESCENCE DETECTION

In this study, we developed a reversed-phase high-performance liquid chromatographic method with fluorometric detection for the simultaneous quantitation of 4-hydroxy-2-hexenal (HHE) and 4-hydroxy-2-nonenal (HNE) in foods by using 1,3-cyclohexanedione reagent. This method provides good resolution and reproducibility. Chromatography is conducted with a gradient system using a mobile phase of methanol–water–tetrahydrofuran (75:25:1, v/v) (A) and acetonitrile (B). The gradient employed is 5% B to 25% B in 25 min; 25% B to 80% in 30 min; isocratic at 80% B in 40 min. The flow rate is 1.0 mL/min. Fluorescence detection is performed at an exciting wavelength of 385 nm and an emission wavelength of 450 nm. The calibration curves for HHE and HNE concentrations are linear from 0.08 to 14 and 0.08 to 5.2 µmol/mL, respectively. The limits of detection and quantitation for HHE are 27 and 160 nmol/mL and those for HNE are 30 and 149 nmol/mL, respectively. Validation data show that the assay is sensitive, specific, accurate, and reproducible for the simultaneous quantitation of HHE and HNE. This rapid method is, therefore, appropriate for quantitating HHE and HNE in fatty foods such as fish and animal meats.

The anti-allergic effect of the ethyl acetate fraction from an Ecklonia kurome extract

To determine the anti-allergic effects of Ecklonia kurome, the ethyl acetate fraction from an E. kurome (EEK) extract was compared to the ethyl acetate fraction from an Eisenia arborea (EEA) extract and epigallocatechin gallate (EGCG) for inhibitory effects on inflammation in experimental animals, degranulation in inflammatory lymphocytes and enzymatic activities involved in allergic reactions. EEK was found to inhibit mouse ear oedema by inflammatory inducers (arachidonic acid, 12-O-tetradecanoylphorbol-13-acetate and oxazolone) in a dose-dependent manner, through both topical and oral administrations. EEK also inhibited degranulation in rat basophilic leukaemia cells and enzymatic activities (cyclooxygenase-2, soybean lipoxygenase and phospholipase A2) in a dose-dependent manner. The effects of EEK were generally comparable of those of EEA and EGCG. Therefore, E. kurome and the components in EEK have the benefit of being used not only in common foods, but also more widely as a functional food resource in anti-allergic foods.

Effects of Chilled Storage, Freezing Rates, and Frozen Storage Temperature on Lipid Oxidation in Meat Blocks from Cultured Bluefin Tuna Thunnus thynnus

ABSTRACT The effects of a short chilled storage period before freezing, frozen storage temperature, and freezing rate on lipid oxidation of bluefin tuna (Thunnus thynnus) meat during frozen storage were investigated. After 12-months storage, all samples had increased in peroxide value though they were less at the lower temperatures (−45 and −60°C). Peroxide values in all samples stored at −20°C increased after 3 months storage, particularly those processed and stored 51 h after harvest. The lowest increase in peroxide value occurred in the samples frozen rapidly 3 h after harvest. Vitamin E levels decreased faster during frozen storage at −20°C. There were no apparent differences in levels of triacylglycerides nor in n-3 fatty acid levels between treatments, storage periods, and storage temperatures. After 12-months storage, headspace oxidative volatiles were highest in samples stored at −20°C and lowest in those stored at −60°C. Lipid oxidation in tuna meat stored at −45°C is similar to that at −60°C, and rapid freezing rather than slow freezing should be used.

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.

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.

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.