Hideo Hatate

Hemolytic suppression roles of taurine in yellowtail Seriola quinqueradiata fed non‐fishmeal diet based on soybean protein

To elucidate the hemolytic suppression roles of taurine and the necessity of dietary taurine supplementation in yellowtail Seriola quinqueradiata fed a diet without fishmeal, juvenile fish with an initial body weight of 250 g were fed for 40 weeks in floating net cages on soybean protein diets supplemented with 0, 3.0, 4.5 and 6.0% taurine. Taurine concentration of the experimental diets were 0.03, 33.9, 52.8 and 71.6 mg/g, respectively. On the 21st week, fish fed the taurine unsupplemented diet had inferior growth and feed performances, higher death, and there were incidences of green liver and hemolytic anemia. In this group, hepatic and plasma taurine concentrations, serum osmolality and osmotic tolerance of erythrocytes (EC50 value) were significantly lower, and plasma hydroperoxide concentration was markedly higher than in the taurine supplemented groups. These conditions markedly improved corresponding with the increase of dietary taurine concentration. These results indicate that taurine plays a role in hemolytic suppression through osmoregulation and biomembrane stabilization in fish. In addition, it is suggested that yellowtail requires dietary taurine as an essential nutrition for maintaining physiological condition normally.

Efficacy of taurine supplementation for preventing green liver syndrome and improving growth performance in yearling red sea bream Pagrus major fed low-fishmeal diet

This study was performed to evaluate the efficacy of taurine supplementation for preventing green liver syndrome and improving growth performance in red sea bream Pagrus major fed a low-fishmeal (FM) diet. Yearling red sea bream were fed for 34 weeks on low-FM diets either supplemented with taurine, or without taurine, and the tissue taurine and bile pigment concentrations were measured. Compared to the fish fed the FM diet, fish fed the low-FM diet without taurine supplementation resulted in inferior feed performances and higher incidence of green liver related to the morphological transformation of the erythrocytes. In these fish, the hepatopancreatic taurine concentration was significantly lower and hepatopancreatic biliverdin concentration was high compared to the fish fed the FM diet. These parameters were markedly improved by taurine supplementation of the low-FM diet and were similar in levels to the fish fed the FM diet. These results indicate that green liver appearance and inferior feed performances of red sea bream fed the low-FM diet without taurine supplementation were caused by dietary taurine deficiency, and indicate the requirement of taurine supplementation to low-FM diets for red sea bream.

Accumulation of hydroxy lipids in live fish infected with fish diseases

Abstract Lipid hydroperoxide (LPO) and hydroxy lipid levels of diseased fishes were investigated. Although significant differences in LPO levels were not always observed between normal and diseased fish, hydroxy lipid levels in muscle and liver were significantly higher in diseased fish than in uninfected normal fish cultured with the same feed in the same cage or in wild normal fish. Hydroxy triglyceride levels of diseased yellowtails with streptococcal infection were significantly elevated in ordinary and dark muscle, and especially in the liver; 1072±78 in diseased fish compared to 632±45 (nmol/g tissue) in normal fish cultured with the same feed. In this case, the polyunsaturated fatty acid contents of the diseased fish were decreased. This was notable, especially with respect to the decrease of docosahexaenoic acid. These trends, namely, increased accumulation of hydroxy lipids in the liver of diseased fish and decreased levels of polyunsaturated fatty acids, were observed in sweetfish with ulcer disease, globefish with Heterobothrium okamotoi infection and/or emaciation disease, red sea bream infected with edwardsiellosis and/or Vibrio anguillarum , yellowtail with jaundiced disease, and carp with cold water disease.

Elevation of lipid peroxide level and production of hydroxy lipids in cultured Hepa-T1 cells by oxidative stressors

In order to investigate the relationships between levels of lipid peroxides (LPO), hydroxy lipids (L-OH) and of antioxidative enzymes in live fish, cultured cells from tilapia liver (Hepa-T1) were treated with oxidative stressors, 2,2′-azobios(2-amidino-propane) dihydrochloride (AAPH) and H2O2. By treating with 5 mM AAPH, LPO and L-OH of the cells significantly increased time-dependently. In particular, L-OH increased from 7.6±0.7 to 23.6±1.8 nmol/mg protein after 2 h of treatment, and synchronously the glutathione peroxidase (GPx) activity of the cells increased from 259±106 to 1970±135 mU/mg protein. In the case of H2O2, however, no elevation of L-OH was observed. In this case, catalase (CAT) and superoxide dismutase (SOD) activities increased time-dependently. Especially, after 2 h exposure, the CAT activity increased remarkably from 217±21 to 2510±120 mU/mg protein, though the GPx activity did not change significantly. These results suggest that the elevation of the L-OH level is closely associated with the elevation of GPx activity, but not with that of CAT or SOD. However, when vitamin E-enriched Hepa-T1 cells were treated with AAPH and H2O2, the production of LPO and L-OH was suppressed significantly. The findings suggest that vitamin E also plays an important role in the levels of the oxidation products in vivo.

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.

Antioxidative Activity Against Superoxide of Anticarcinogenic Tea-Leaf Catechins: Measurement by the Cypridina Chemiluminescence Method

The reaction constants between superoxide (O2 -) and tea-leaf catechins, whose anticarcinogenic activity to stomach cancer has been confirmed, were measured using the Cypridina chemiluminescence method for measuring rate constants between O2 - and antioxidants established in our previous report. The quenching experiments of chemiluminescence of a Cypridina luciferin analog, 2-methyl-6-phenyl-3,7-dihydroimidazo[1,2-a]pyrazin-3-one (CLA) in 25mM buffer solution (pH 7.0) at 25°C were used. Small amounts of antioxidants were needed for the measurement (<10mg). The activities are expressed in quenching constants so we can compare them quantitatively. Tea-leaf catechins showed reaction rate constants ranging from 104 to 106M-1s-1 (as large as ascorbic acid). Some teas showed reactivity to superoxide as well as peroxide values. The results were compared with the data in the literature. They prove that tea-leaf catechins have strong antioxidative activity against O2 - in aqueous solutions and suggest that superoxide can cause stomach cancer. We also found that the present measuring method is applicable to the measurement of reaction rate constants of antioxidative samples against superoxide even when the samples are fairly unstable.

Selective Hydrolysis of the 3,6-Anhydrogalacotosidic Linkage in Red Algal Galactan: A Combination of Reductive Acid Hydrolysis and Anhydrous Mercaptolysis

Here we report a simple method for the structural analysis of red algal galactan containing 3,6-anhydrogalactose. Structural heterogeneity in the galactan was demonstrated by this method. For selective hydrolysis of 3,6-anhydrogalactosidic linkages in the galactan, conditions for reductive mild acid hydrolysis were examined by characterizing the resulting oligosaccharide alditols by anhydrous mercaptolysis. Residues other than alditols at the reducing ends, including labile 3,6-anhydrogalactose, were liberated quantitatively as diethyl dithioacetal derivatives, whereas alditols at the reducing ends were not derivatized and were liberated as alditols intact. The liberated sugars were then separated and measured quantitatively by gas-liquid chromatography. Heating of agarose in reductive hydrolysis with 0.3 M trifluoroacetic acid in the presence of an acid-stable reducing agent, 4-methyl morpholine borane, at 80 °C for 90 min and for 90 °C for 45 min was found to be optimum for the selective hydrolysis of 3,6-anhydrogalactosidic bonds, without detectable cleavage of other glycosidic bonds.

Analysis of functional components and radical scavenging activity of 21 algae species collected from the Japanese coast

The functional chemical substances and the antioxidant activity of lipids in 21 marine algae along the Japanese coast were investigated. Principal component analysis was performed to detect any correlation between the chemical substances and algae phylum. Chlorophyta contained a high level of β-carotene. Rhodophyta contained high amounts of cholesterol, β-sitosterol, and saturated fatty acids. Phaeophyta were rich in fucosterol, α-tocopherol, fucoxanthin, and polyphenol. Phaeophyta algae also showed the highest antioxidant activity compared with other phylum. This suggests that Phaeophyta has the greatest potential to be used as a functional food. Consumption of the beneficial Phaeophyta species, such as Eisenia arborea Areschoug and Ecklonia cava Kjellman should be encouraged as not only as food products but also as nutraceuticals and dietary supplements. These beneficial ingredients should be encouraged to be studied in depth with the possibility to develop specific formulated products target to special consumers population with added nutritional value.

Determination of Biogenic Amines in Fish Meat and Fermented Foods Using Column-Switching High-Performance Liquid Chromatography with Fluorescence Detection

In this study, we developed a column-switching high-performance liquid chromatography method with fluorescence detection for the simultaneous analysis of biogenic amines (BAs). This method uses an isocratic solution using acetonitrile with water as the mobile phase. Column-switching is achieved by using a switching valve with a set time program to change flow direction. Using this method, seven BAs (tryptamine, 2-phenylethylamine, putrescine, cadaverine, histamine, tyramine, and spermidine) could be separated and impurities eliminated. Using fluorescence detection, BAs could be identified with high sensitivity. We employed this method to determine the BA contents of fish (mackerel, tuna, and cod) and fermented food (a soybean product and cheese). Our results are in line with previous reports, yielded highly reproducible and quantitative results, and enabled the quick and simultaneous analysis of multiple BAs. Therefore, the method developed here may be useful for the continuous analysis of BAs in different samples to evaluate food quality.

Chemiluminescent Products of the Maillard Reaction: Studies on Model Systems

Chemiluminescent intermediates were prepared from a model Maillard reaction between phenylglyoxal and benzylamine under an oxygen atmosphere as a solid material that gives light emission in the visible region. Such chemiluminescence is similar to that first detected by us from representative Maillard reactions, such as those from glucose and lysine or methylglyoxal and methylamine, both in the presence or absence of oxygen. This suggests that the material in the present studies contains peroxide compound(s). The model Maillard reaction did not give near-infrared luminescence at 1270 nm, which is characteristic of singlet oxygen formation. Structural studies were attempted on the solid material by means of chemical, chromatographic, and spectral methods.