Masaaki Takeuchi

Effect of astaxanthin rich red yeast (Phaffia rhodozyma) on oxidative stress in rainbow trout.

The antioxidative biological effect of dietary red yeast, Phaffia rhodozyma, which is rich in astaxanthin, on rainbow trout, Oncorhynchus mykiss, was examined. The levels of serum transaminase (glutamic-pyruvic transaminase and glutamic-oxaloacetic transaminase) activities and of lipid peroxides (LPO) of fish fed oxidized oil were significantly higher than those of the control fish fed non-oxidized oil. However, the supply of red yeast considerably decreased both enzyme activities and LPO level. Furthermore, the serum lipid (triglycerides, total cholesterol and phospholipids) concentrations were also significantly decreased. Especially, the serum triglyceride level of fish fed the red yeast was as low as that of the control. It was also observed that there were no significant differences in muscle LPO levels between the fish fed red yeast and the control. The present results suggest for the first time that dietary red yeast may effectively suppress the LPO generation of tissue and normalize liver function as well as improving muscle pigmentation of trout. Thus, red yeast should have a reducing effect on oxidized oil-induced oxidative stress in fish.

Bactericidal Activity of a Fermented Hot-Water Extract from Stevia rebaudiana Bertoni towards Enterohemorrhagic Escherichia coli O157:H7 and Other Food-Borne Pathogenic Bacteria

A fermented aqueous extract from Stevia rebaudiana Bertoni showed strong bactericidal activity towards a wide range of food‐borne pathogenic bacteria including enterohemorrhagic Escherichia coli O157:H7. The colony‐forming ability of the food‐borne pathogenic bacteria tested so far was reduced to < 10−7 when exposed to ⩾40% (v/v) solutions of the fermented extract at 37 C for 2 hr. Secretion of verocytotoxin 1 and 2 by enterohemorrhagic E. coli was also diminished by fermented extract at a concentration of ⩾10% (v/v). In contrast, the fermented extract did not significantly kill Bifidobacteria or Lactobacilli. The active principle(s) of the fermented Stevia extract were bactericidal under acidic conditions.

Distribution of opine dehydrogenases and lactate dehydrogenase activities in marine animals

Abstract 1. 1. Opine dehydrogenases (OpDHs) and lactate dehydrogenase (LDH) activities were determined in various marine animals. OpDHs were detected in six marine invertebrate phyla; Porifera, Coelenterata, Annelida, Mollusca, Arthropoda and Echinodermata in phylogenic sequence. 2. 2. Among several OpDHs, tauropine dehydrogenase (TaDH) occurred widely in marine invertebrates, from Porifera to Echinodermata. 3. 3. With a few exceptions, total OpDHs activities exceeded that of LDH activity in the marine invertebrates investigated. 4. 4. With respect to anaerobic glycolysis, OpDHs are indicated to play an important role in phylogenically lower invertebrates, whereas LDH is more important in higher animals.

Unique molecular properties of superoxide dismutase from teleost fish skin

A unique Cu,Zn‐SOD was found and isolated from plaice Paralichthys olivaceus skin. Surprisingly, the properties of purified fish skin SOD were very different from those of SOD from other sources reported so far. The purified SOD was composed of four same subunits of 16 kDa and the molecular weight of the native SOD was found to be around 65 kDa. The dominant amino acids of the SOD were Ser, Thr, Pro and Glu. Above 70°C, thermostability of the SOD was much lower than that of bovine erythrocyte Cu,Zn‐SOD.

Characterization of catalase from the seaweed Porphyra yezoensis

Abstract Catalase was partially purified from the marine red macroalga Porphyra yezoensis by sequential ammonium sulfate fractionation, ion-exchange and hydrophobic interaction chromatography. Extraction from frozen and powdered material under liquid nitrogen was more efficient than that from fresh or freeze-dried material. The maximal activity of the enzyme was observed in the pH range 6.0–11.0, but the activity rapidly decreased below pH 6.0. The enzyme had an optimum reaction temperature at 30°C, but the activity was almost completely lost at 60°C. Heme-catalase inhibitors, such as hydroxylamine, azide and cyanide, inhibited the enzyme activity markedly. The enzyme was also inactivated by both dithiothreitol and 2-mercaptoethanol.

Studies on the carotenoids in the muscle of salmon. V, Combination of astaxanthin and canthaxanthin with bovine serum albumin and egg albumin

1. Bovine serum albumin (BSA) and/or egg albumin were bound to astaxanthin or canthaxanthin easily and the spectroscopic characteristics of these complexes were similar to those of astaxanthin or canthaxanthin in the salmon muscle. 2. This result indicates that astaxanthin-BSA, -egg albumin, canthaxanthin-BSA and -egg albumin complexes were basically similar to astaxanthin-actomyosin and/or canthaxanthin-actomyosin complex in the salmon muscle. 3. The binding of salmon actomyosin to astaxanthin or canthaxanthin is not specific.

Partial purification and properties of glutathione peroxidase from carp hepatopancreas

1. Two glutathione peroxidases (GSH-Px), D1 and D2, were partially purified from the hepatopancreas of common carp Cyprinus carpio by ion-exchange, gel filtration, and hydrophobic chromatography. The enzymatic properties of those enzymes were examined. 2. The D1 and D2 differed in following enzymatic properties. The pH optima of D1 and D2 were 8.0 and 9.0, respectively. 3. When stored at pH 4.0 for 36 hr, D1 kept 70% of maximal activity while only 30% of that was shown in D2. 4. D1 and D2 lost activity by 50% when incubated at 55 degrees C and 65 degrees C for 10 min, respectively.

Detection of plasmalogen from plasma low density lipoprotein and high density lipoprotein in carp, Cyprinus carpio, and rainbow trout, Oncorhynchus mykiss.

The study revealed the presence of plasmalogens in the low density lipoprotein (LDL) and high density lipoprotein (HDL) of the fish. The composition of the plasmalogen in the carp plasma LDL phospholipids was 0.94 and 0.23% in the HDL; the LDL phospholipids in the rainbow trout were 0.44% and the HDL was 0.18%. Aldehydes from the plasmalogen were derivatized with dansylhydrazides and separated by high performance liquid chromatography (HPLC). Their presence was detected using a fluorescence detector. Hexadecanal (C16: 0), octadecanal (C18: 0) and octadecenal (C18: 1) were determined to be the major components in the carp and rainbow trout.

Purification and properties of tauropine dehydrogenase from a red alga, Rhodoglossum japonicum

Tauropine dehydrogenase which is a member of ‘opine’ dehydrogenases and catalyzes the reductive condensation of taurine with pyruvate was purified from a red alga, Rhodoglossum japonicum using a combination of ammonium sulfate fractionation, gel filtration, affinity, and ion exchange chromatography. The molecular mass of this enzyme, obtained by HPLC using TSK SW2000G in its native form and SDS-PAGE in its denatured form, was 39000 and 42000, respectively. This means tauropine dehydrogenase has monomeric structure like other opine dehydrogenases. The relative activities for amino acids as substrate were 100 for taurine, 17 for valine and 12 for homotaurine. The apparent Km values for taurine, pyruvate and NADH were 15.0 mM, 0.80 mM and 0.04 mM, and for tauropine and NAD+ were 30 mM and 0.12 mM, respectively. Diurnal change of tauropine content was observed in R. japonicum, tauropine increased in the daytime and decreased in the nighttime.