• Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.113-117
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• 2005

To prepare oligouronic acids from high-molecular-weight alginates, sea tangle Laminaria japonicus alginates were hydrolyzed at $80^{\circ}C$ for various hydrolysis times (HT). The effects of hydrolysis time on the distribution ratios (DR) of the molecular weights (MW) of the hydrolyzed alginates were in-vestigated. As HT increased, the DR of the alginates with MW>500 kDa decreased ex-ponentially, while those with MW=50-100 kDa or MW<50 kDa increased exponentially. For MW=300-500 kDa, DR increased exponentially until HT reached 60 min, and then decreased exponentially. Similarly, for MW=100-300 kDa, DR increased exponentially until HT reached 90 min, and then decreased.

• YAKHAK HOEJI
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• v.48 no.6
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• pp.374-378
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• 2004

To investigate the whitening activity of Laminaria japonicus, we measured the effect of hot-water extracts on melanin production in B16 melanoma cells. Melanocyte stimulating h ormone (MSH, $1{\mu}M$)-stimulated melanin production in B16 melanoma cells was significantly inhibited by fucoidan and hot-water extracts, but not by alginate. The purified tyrosinase activity was not affected by hot-water extracts, alginate and fucoidan. However, tyrosinase expression was significantly inhibited by fucoidan and hot-water extract in Western blot. These results suggest that inhibitory mechanism of hot-water extracts on melanin production may be due to the inhibition of tyrosinase expression but not to direct inhibition of tyrosinase, such an effect of which may be dependent on fucoidan.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.4
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• pp.325-330
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• 2000

Alginate obtained from brown algae had various physicochemical and rheological properties and could used as a dietary fiber, However, alginate has not been widely applied to the food industry, since it had high viscosity, high gelling effect conjugated with some mineral, and low solubility. To improve functionality of alginate, partially develymerized alginates, which was water-soluble dietary fiber were obtained by hydrolysis of alginate from the sea tangle, Laminaria japonicus, heated at $121^{\circ}C$. Effects of depolymerization of alginate on the changes of viscosity and average molecular weight, block composition ratio of mannuronate to guluronate (M/G ratio), chemical properties using $PT-IR, ^1H-NMR, and ^(13)C-NMR$ spectrum were investigated. The average molecular weight and viscosity of the alginate were rapidly decreased with the thermal decomposition, and estimated to be 1,307,415 dalton and 284,000 cps, before heating, 728,106 and 3,940.29 cps after 30 min heating, 102,635 and 22.22 cps after 2.5 hrs heating, 51,205 and 12.05 cps after 3 hrs, and 10,049 and 4.28 cps after 6.5 hrs, respectively. The M/G ratio was increased with the heating time, while MM-block did not show any changes and GG-block diminished. The results of $FT-IR, ^1H-NMR and ^(13)C-NMR$ spectrum suggested that changes of molecular structure did not occur by the thermal decomposition.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.393-398
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• 2000

To extend utilization of alginate from the sea tangle, Laminaria japonicus, depolymerized alginates (HAG-10, average molecular weight 10,000; HAC-50, average molecular weight 50,000; HAG-100, average molecular weight 100,000) were obtained by hydrolysis of alginate by heating at $12^{\circ}C$. The effects of each depolymerized alginate on excretion of cholesterol, glucose and namium in rats were investigated. The total excretion rate (${\%}$) of cholesterol and cadmium was the highest in rats administered with HAG-50, The rate was $45.81{\%} and 59.02{\%} with HAG-50$. It was high in the order of $45.78{\%} and 56.05{\%}$ in HAG-100, $41.28{\%}$ and $55.96{\%}$ in alginate, and $32.11{\%} and 44.92{\%} in HAC-10$, respectively. In the case of HAG-50, it significantly (p<0.01) prevented the serum glucose level of rats from rising within 30 min and 60 min after glucose loading or administration among all the samples, but it had no particular effects on the serum insulin level. In conclusion, it was suggested that HAG-50, in which the alginate had a decreased molecular weight, while still retaining its desirable functions as a dietary fiber, was effective in excretion of harmful substances, such as cadmium and cholesterol, and in lowering glucose activities in serum of rats.

• Journal of Life Science
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• v.11 no.5
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• pp.476-482
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• 2001

The study was undertaken to determine the effect of the aqeuous extract of sea tangle, Laminaria japonicus, on the activites of glucokinase and hexokinase in the pancreas of diabetic mellitus mice which were induced by alloxan. After one week of alloxan injection, the levels of serum glucose and insulin secretion were dramatically increased, however, the insulin secretion was decreased with administration of sea tangle extract. Alloxan injection allowed the serum glucose level to increase and level was decreased by sea tangle extract administration. Furthermore, it was observed the sea tangle extract was effective in recovering the levels of insulin secretion. Enzyme activities of the glucokinase and hexokinase were decreased by alloxan treatment. In contrast, sea tangle extract administration to the mice allowed to increase proportionally. These results suggested that sea tangle extract is highly effective in treatment of diabetic mellitus induced by alloxan.

• Fisheries and Aquatic Sciences
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• v.20 no.10
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• pp.24.1-24.8
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• 2017

The experiment was conducted to investigate the effects of different algae in diet on growth, survival, and interleukin-10 productions of sea cucumber. At first, a 9-week feeding trail was conducted to evaluate the growth performance and survival of the sea cucumber fed one of the six experimental diets containing ST (Sargassum thunbergii), UL (Ulva lactuca), UP (Undaria pinnatifida), LJ (Laminaria japonica), SS (Schizochytrium sp.), and NO (Nannochloropsis oculata) in a recirculating aquaculture system. The result showed that survival was not significantly different among the dietary treatments, and the specific growth rate (SGR) of sea cucumber fed the UL diet ($1.58%d^{-1}$) was significantly higher than that of sea cucumber fed the other diets (P < 0.05), except for the LJ and NO diets. Secondly, interleukin (IL)-10 gene expression was determined where mice splenocytes were stimulated with $10{\mu}g\;ml^{-1}$ of sea cucumber extracts for 2 h. The result showed that IL-10 gene expression levels were significantly increased in UL, LJ, and NO diets fed sea cucumber extracts compared to other experimental diets. The results suggest that dietary inclusion with Ulva lactuca, Laminaria japonica, and Nannochloropsis oculata algae may improve the growth of juvenile sea cucumber and could upregulate IL-10 gene expression in mice splenocytes. Such detailed information could be helpful in further development of more appropriate diets for sea cucumber culture.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.33 no.5
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• pp.388-392
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• 2000

To improve functionality and characteristics of alginate from the sea tangle, Laminaria japonicus, partially depolymerized alginates (HAG-10, average molecular weight 10,000; HAG-50, average molecular weight 50,000; HAG-100, average molecular weight 100,000) were obtained with hydrolysis of alginate by heating at $12^{\circ}C$. Effects of the depolymerization on physicochemical properties were investigated in the antimutagenicity and binding capacity of cholesterol, glucose and cadmium. In the Ames mutagenicity test using Salmonella typhimurium TA 100, HAG-10, HAG-50, HAG-100 and intact alginate reduced effectively the mutagenicities induced by aflatoxin $B_1 (AFB_1)$ and N-methyl-N'-nitro-N-nitrosoguanidine(MNNG) and HAG-10 showed the strongest antimutagenicity among the tested samples. The binding capacity of cholesterol, glucose and cadmium at different pH in vitro depended highly on molecular weight of alginate, and the changes in binding capacity at different pH was not different.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.2
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• pp.142-147
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• 2018

This study was conducted to investigate the effects of practical diets containing different seaweed powders on the growth and body composition of juvenile sea cucumber Apostichopus japonicus. Six experimental diets were formulated to contain 40% of the following seaweed powders: Sargassum thunbergii (ST), Undaria pinnatifida (UP), Ascophyllum nodosum (AN), Hizikia fusiformis (HF), fermented Laminaria japonica (FLJ), and fermented Hizikia fusiformis (FHF). Sea cucumbers (30 per tank; initial mean weight $0.4{\pm}0.01g$) in three replicates of six groups were fed one of the six experimental diets for 15 weeks. Survival in all groups was 83-93%, with no significant differences among the experimental groups. The specific growth rates of the sea cucumbers fed the ST and UP diets were significantly higher than those of sea cucumbers fed the HF, FLJ, and FHF diets, but did not significantly differ from those of sea cucumbers fed the AN diet. The results of this study suggest that S. thunbergii, U. pinnatifida, and A. nodosum could be useful sources of seaweed powder for practical diets of juvenile sea cucumber.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.1
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• pp.21-26
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• 2001

To examine functionality of depolymerized alginate obtained by hydrolysis of alginate through a heating process at $121^{\circ}C$ on gastrointestinal physiology, the changes of body weight, organ weight and length, pancreatic and small intestinal composition, and light microscopy (LM) observation of small intestinal microvilli's appearances were checked in the rats. Rats were fed diets containing $1\%, 5\%, and 10\%$ of each depolymerized alginate (HAG-10, HAG-50, HAG-100) and alginate for 35 days, The feeding of 5 and $10\%$ HAG-50 and $10\%$ alginate diets for 35 days significantly depressed the body weight gain, but increased the length and weight of the small intestine and cecum in rats (p<0.01). Pancreatic protease activity was decreased significantly (p<0.01) in all groups except lo/o of HAG-10 diets, but the protein content increased in all groups, However, pancreatic amylase and lipase activities as well as DNA and RNA content were not significantly different. The small intestinal protein and the DNA content were the highest in diets fed $5\%$ HAG-50; RNA content increased significantly (p<0.01) in all groups except in the fiber-free diets. Light microscopy (LM) observation showed growth of small intestinal microvilli with numerous ridges; the multiplication of the convolution goblet cells in rats fed with diets containing $5\%$ of HAG-50 were more than others group.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.2
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• pp.77-83
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• 2001

To clarify functionality of depolymerized alginate obtained by hydrolysis of alginate through a heating process at $121^{\circ}C$ on gastrointestinal physiology, the effects of a depolymerized alginate on fecal microflora and the intestinal environment were studied in rats. Rats were fed with diets containing 1, 5 and $10\%$ of each depolymerized alginate (HAG-10, HAG-50 and HAG-100) and alginate for 35 days, Among 20 species of authentic intestinal bacteria, Bacteroides ovatus showed the abilities to ferment HAG-10 HAG-50, HAG-100 and alginate, The 1, 5 and $10\%$ of HAG-50 and $1\%$ of alginate diets resulted in the increased ratio of Bifidobacterium and Lactobacillus to total bacteria, while the 5 and $10\%$ alginate diets decreased in feces of rats, significantly (p<0.01). These results suggested that $5\%$ HAG-50 diets contribute to an improvement of intestinal microflora in rats.