• Korean Journal of Fisheries and Aquatic Sciences
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• v.26 no.6
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• pp.529-537
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• 1993

Several methods were examined for purification of docosahexaenoic acid (DHA, 22:6n-3) from skipjack Euthynnus pelamis orbital tissue oil, a marine by-product, and a modified method for isolation of a high purity DHA was proposed. Skipjack orbital tissue contained $55.4\%$ of total lipid(TL), and DHA accounted for $23.7\%$ of the TL. Application of low-temperature crystallization and urea inclusion compound methods to the orbital fatty acid mixture resulted in increases of DHA concentrations to approximately $46\%\;and\;61\%$, respectively. These methods were suitable for large production of DHA with relative low purity because of the simple purification procedure. DHA of approximately $74\%$ in purity was obtained by silver nitrate aqueous solution method, but the method gave a very low recovery($<10\%$). Silver nitrate-impregnated silica column chromatography was suitable for purification of a high purity DHA(purity, $>98\%$ and recovery, $>90\%$) A modified method, silver nitrate-impregnated silica column chromatography combined with low-temperature crystallization(two step purication method) was proposed as the most effective method to obtain DHA with high purity($99.9\%$) from the skipjack orbital oil.

• Food Science of Animal Resources
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• v.43 no.2
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• pp.220-231
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• 2023

Although omega-3 fatty acids including docosahexaenoic acid (DHA) contain various health-promoting effects, their poor aqueous solubility and stability make them difficult to be induced in dairy foods. The aims of this research were to manufacture casein derivative-based delivery system using acid-induced gelation method with glucono-σ-lactone and to investigate the effects of production variables, such as pH and charged amount of linoleic acid, on the physicochemical properties of delivery systems and oxidative stability of DHA during storage in model milk. Covalent modification with linoleic acid resulted in the production of casein derivatives with varying degrees of modification. As pH was reduced from 5.0 to 4.8 and the charged amount of linoleic acid was increased from 0% to 30%, an increase in particle size of casein derivative-based delivery systems was observed. The encapsulation efficiency of DHA was increased with decreased pH and increased charged amount of linoleic acid. The use of delivery system for DHA resulted in a decrease in the development of primary and secondary oxidation products. An increase in the degree of modification of casein derivatives with linoleic acid resulted in a decrease in the formation of primary and secondary oxidation products than of free DHA indicating that delivery systems could enhance the oxidative stability of DHA during storage in model milk. In conclusions, casein derivatives can be an effective delivery system for DHA and charged amount of linoleic acid played a key role determining the physicochemical characteristics of delivery system and oxidative stability of DHA.

• Journal of Nutrition and Health
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• v.28 no.11
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• pp.1078-1090
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• 1995

This study was undertaken to elucidate the effect of DHA rich fish oil(DHA rich oil) added to different dietary fats on thrombosis and lipid peroxidation. Rats were fed perilla oil, sesame oil and beef tallow with or without DHA rich oil for 12 weeks. Bleeding time was the longest in Perilla oil groups with or without DHA rich oil. The productions of thromboxane B2(TX B2) and 6-keto Prostaglandin F1$\alpha$(6-keto PG F1$\alpha$) were the highest in Esame oil group without DHA rich oil. Bleeding time tended to be extened and group showed the most antithrombotic effect among three oil groups when DHA rich oil added. The antithrombotic effect by DHA rich oil addition seemed to be resulted from the increase of dietary n-3 fatty acid rather than DHA. And there was not the difference in antithrombotic effect between DHA and $\alpha$-linolinic acid. The level of TBARS(thiobarbituric acid reactive substances) in plasma and liver, and the activities of lipid peroxide metabolizing enzymes(catalase, superoxide dismutase and gluthathion peroxidase) in erythrocyte and liver were not affected by the dietry fat type and DHA rich oil addition, except that activity of hepatic catalase was increased by DHA rich oil addition. Therefore it revealed the DHA level added in this study seldom affected lipid peroxidation. However, it dose not conclude that DHA level of this study make low production of lipid peroxide because the peroid of our study was short.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.7
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• pp.1047-1053
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• 2006

The current study was designed to determine the effects of dietary docosahexaenoic acid (DHA) on fatty acid deposition in egg yolk and various tissues of laying Tsaiya ducks, and on the mRNA concentrations of hepatic lipogenesis-related transcription factors. Thirty laying ducks were randomly assigned to three treatments with diets based on corn-soybean meal (ME: 2803 kcal/kg; CP: 17.1%; Ca: 3.4%) supplemented with 0% (control diet), 0.5% or 2% algal DHA oil. The DHA content in egg yolks of the ducks was elevated significantly (p<0.01) with the supplementation of dietary DHA. The DHA percentage of the total fatty acids in the egg yolk of laying ducks was 0.5%, 1.3% and 3.4% for 0%, 0.5% and 2% algal DHA oil treatments, respectively, for the $1^{st}$ week, and 0.5%, 1.5% and 3.3% for the $2^{nd}$ week. Therefore, algal DHA oil can be utilized by laying Tsaiya ducks to enhance the egg-yolk DHA content. The concentrations of triacylglycerol (TG) and cholesterol in plasma of laying Tsaiya ducks were not affected by dietary DHA treatments (p>0.05). The DHA concentration in plasma, liver, and skeletal muscle was increased with the addition of dietary algal DHA oil (p<0.05). The mRNA abundance of sterol regulatory element binding protein 1 (SREBP1) and SREBP2 in the livers of laying Tsaiya ducks was not affected by dietary DHA, suggesting that the expression of these transcription factors is tightly controlled and not sensitive to DHA treatments.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.4
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• pp.301-307
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• 2009

Inflammatory processes of vascular endothelial cells play a key role in the development ofatherosclerosis. We determined the anti-inflammatory effects and mechanisms of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on LPS-treated human umbilical vein endothelial cells (HUVECs) to evaluate their cardioproteerive potential. Cells were pretreated with DHA, EPA, or troglitazone prior to activation with LPS. Expression of COX-2, prostaglandin $E_2$ ($PGE_2$) and IL-6 production, and $NF-{\kappa}B$ activity were measured by Western blot, ELISA, and luciferase activity, respectively. Results showed that EPA, DHA, or troglitazone significantly reduced COX-2 expression, $NF-{\kappa}B$ luciferase activity, and $PGE_2$ and IL-6 production in a dose-dependent fashion. Interestingly, low doses (10 ${\mu}$M) of DHA and EPA, but not troglitozone, significantly increased the activity of $NF-{\kappa}B$ in resting HUVECs. Our study suggests that while DHA, EPA, and troglitazone may be protective on HUVECs under inflammatory conditions in a dose-dependent manner. However there may be some negative effects when the concentrations are abnormally low, even in normal endothelium.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.10
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• pp.1451-1456
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• 2005

To study the acute effect of dietary docosahexaenoic acid (DHA, $C_{22:6}$) on the expression of adipocyte determination and differentiation-dependent factor 1 (ADD1) mRNA in pig tissues, weaned, crossbred pigs (28 d of age) were fed with either 10% (on as-fed basis) tallow (high stearic acid), soybean oil (high linoleic acid), or high DHA algal oil for 2 d. The plasma and liver DHA reflected the composition of the diet. The adipose tissue and skeletal muscle DHA did not reflect the diet in the short term feeding. The results also showed that the diet containing 10% algal DHA oil significantly decreased the total plasma cholesterol (39%) and triacylglycerol (TG; 46%) in the pigs. Soybean oil significantly decreased plasma TG (13.7%; p<0.05), but did not have an effect on plasma cholesterol. The data indicate that different dietary fatty acid compositions have different effects on plasma lipids. The ADD1 mRNA was decreased (p<0.05) in the liver of DHA oil-treated pigs compared with the tallow-treated pigs. The diets did not have significant effect on the ADD1 mRNA in adipose tissue. Addition of algal DHA oil in the diet increased acyl CoA oxidase (ACO) mRNA concentration in the liver, suggesting that dietary DHA treatment increases peroxisomal fatty acid oxidation in the liver. However, dietary soybean oil supplementation did not affect mRNA concentrations of ADD1 or ACO in the tissues of pigs. Because ADD1 increases the expression of genes associated with lipogenesis, and ACO is able to promote fatty acid oxidation, feeding DHA oil may change the utilization of fatty acids through changing the expression of ADD1 and ACO. Therefore, feeding pigs with high DHA may lead to lower body fat deposition.

• Journal of Microbiology and Biotechnology
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• v.20 no.2
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• pp.340-345
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• 2010

The culture variables were optimized to increase 1,3-dihydroxyacetone (DHA) production by Gluconohacter oxydans ZJB09112 in shake flasks and bubble column bioreactors. After fermentation in the optimized medium (g/l: yeast extract 5, glycerol 2.5, mannitol 22.5, $K_2HPO_4$ 0.5, $KH_2PO_4$ 0.5, $MgSO_4{\cdot}7H_2O$ 0.1, $CaCO_3$ 2.0, pH 5.0), when five times of glycerol feeding were applied, $161.9{\pm}5.9\;g/l$ of DHA was attained at a $88.7{\pm}3.2%$ conversion rate of glycerol to DHA.

• Korean Journal of Poultry Science
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• v.35 no.3
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• pp.255-265
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• 2008

The objective of this study was to evaluate the docosahexaenoic acid(DHA) levels of meats and eggs from chickens which were fed fermented soybean meal(FSM) by marine microalgae(Schizochytrium mangrovei MM103). The diets contained different amounts of FSM at 0, 3, 5 and 10%. DHA content of carcass was increased with dietary FSM. DHA amounts in the breast meat were higher in the 10% FSM diet(2.21%) than the 5%(1.65%) and 3%(1.18%) FSM, and similar results were observed in the leg meat(10% FSM: 2.21%; 5% FSM: 1.65%; and 3% FSM: 1.18%, respectively) and in eggs(10% FSM: 2.02%; 5% FSM: 1.22%; and 3% FSM: 0.73%). The level of n-3 polyunsaturated fatty acids such as DHA(22:6n-3) in the FSM treatment was significantly higher than those of the other groups(P<0.05). The results demonstrated that FSM by marine microalgae could be used to enhance DHA amounts in chicken meats and eggs.

• Nutritional Sciences
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• v.9 no.1
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• pp.9-13
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• 2006

The differential effects of various fatty acids such as n-3 and n-6 types or degrees of unsaturation on the CYP2E1 induction and the production of lipid peroxidation (LPO) were investigated. The CYP2E1-transduced human hepatoma HepG2 cells (E47) were cultured in RPMI 1640 media containing different concentrations of various fatty acids up to 48 h incubation compared to 04 cells and CYP2E1-null cells. Treated fatty acids were linoleic acid (LA:n-6, C18:2), arachidonic acid (AA:n-6, C20:4) and docosahexaenoic acid (DHA:n-3, C22:6). The cell survival rate was decreased corresponding to the degree of unsaturation (LA>AA $\cong$DHA) and to LPO production in E47 and 04 cells. The four or five unsaturation degree of fatty acids, AA and DHA, caused time- and dose-dependent cell death in E47 cells but not as much as in C34 (without CYP2E1), suggesting an important role of CYP2E1 in the DHA mediated damage. In the levels of lipid peroxides (LPO), AA also elevated LPO by 3- and 5- fold compared to DHA or LA treated E47 cells. However, AA did not increase LPO until 48 h incubation in C34 cells. In conclusion, the polyunsaturated fatty acids induced CYP2E1 induction might be changed by the elevated levels of lipid peroxide (LPO) and oxidative stress through the connection of CYP2E1 and degrees of unsaturated fatty acids.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.5
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• pp.768-774
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• 2007

To study the effect of dietary docosahexaenoic acid (DHA) enrichment on the expression of hepatic genes in pigs, weaned, crossbred pigs (30 d old) were fed diets supplemented with either 2% tallow or DHA oil for 18 d. Hepatic mRNA was extracted. Suppression subtractive hybridization was used to explore the hepatic genes that were specifically regulated by dietary DHA enrichment. After subtraction, we observed 288 cDNA fragments differentially expressed in livers from pigs fed either 2% DHA oil or 2% tallow for 18 d. After differential screening, 7 genes were found to be differentially expressed. Serum amyloid A protein 2 (SAA2) was further investigated because of its role in lipid metabolism. Northern analysis indicated that hepatic SAA2 was upregulated by dietary DHA enrichment (p<0.05). In a second experiment, feeding 10% DHA oil for 2d significantly increased the expression of SAA2 (compared to the 10% tallow group; p<0.05). The porcine SAA2 full length cDNA sequence was cloned and the sequence was compared to the human and mouse sequences. The homology of the SAA2 amino acid sequence between pig and human was 73% and between pig and mouse was 62%. There was a considerable difference in SAA2 sequences among these species. Of particular note was a deletion of 8 amino acids, in the pig compared to the human. This fragment is a specific characteristic for the SAA subtype that involved in acute inflammation reaction. Similar to human and mouse, porcine SAA2 was highly expressed in the liver of pigs. It was not detectable in the skeletal muscle, heart muscle, spleen, kidney, lung, and adipose tissue. These data suggest that SAA2 may be involved in mediation of the function of dietary DHA in the liver of the pig, however, the mechanism is not yet clear.