• Applied Biological Chemistry
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• v.41 no.6
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• pp.414-420
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• 1998

We studied the difference effects of dietary ${\alpha}-linolenic\;acid\;({\alpha}-LA,\;18:3\;n-3)$, eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3) on the lowering of triacylglycerol in the liver and serum on lipid metabolism in rats. Rats were fed semipurified diets containing 10% fat with constant polyunsaturated/monounsaturated/saturated fatty acids (1:1:1) and n-6/n-3 ratio (1:2). EPA (98%) and DHA (98%) were added in diets as the ethyl esters. The concentration of liver triacylglycerol was significantly lower in rats fed both EPA and DHA than in those fed ${\alpha}-LA$. The concentration of liver phospholipid was significantly higher in rats fed DHA than in those fed ${\alpha}-LA$ and EPA. Both EPA and DHA reduced serum triacylglycerol concentration compared with ${\alpha}-LA$, but this effect was more pronounced in the EPA diet. The activity of phophatidate phosphohydrolase in the liver microsome was significantly lower in rats fed both EPA and DHA than in those fed ${\alpha}-LA$. but, there was no significant difference on the activities of diacylglycerol acyltransferase among the three groups. The concentration of liver triacylglycerol were correlated with changes in the microsomal phosphatidate phosphohydrolase activity (r=0.84). Hepatic NADPH generating enzyme, glucose-6-phosphate dehydrogenase was more effective to reduce the activity in rats fed both EPA and DHA than in those fed ${\alpha}-LA$. In conclusion, EPA or DHA reduced the hepatic triacylglycerol concentration by inhibiting microsomal phosphatidate phosphohydrolase, thereby inhibiting synthesis of triacylglycerol in the liver.

• 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.

• Journal of Microbiology and Biotechnology
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• v.6 no.5
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• pp.358-360
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• 1996

Solvent extraction, soxhlet method, and supercritical fluid extracion were considered, respectively, as the method of choice for the recovery of DHA from lyophilized Thraustochitrium sp., and the results of corresponding extraction were compared. Supercritical fluid extraction seems to be the most appropriate process with respect to time, process simplicity, and extractant intoxicity.

• Fisheries and Aquatic Sciences
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• v.17 no.1
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• pp.95-103
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• 2014

This study was carried out to investigate the influences of dietary levels, ratios and sources of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the growth and fatty acid compositions of juvenile olive flounder Paralichthys olivaceus. Sixteen diets containing five levels of EPA (0.5%, 1.0%, 1.5%, 2.0%, and 4.0%), five levels of DHA (0.5%, 1.0%, 1.5%, 2.0% and 4.0%), three ratios of EPA/DHA (75/25, 50/50 and 25/75), two levels of squid liver oil (5% and 10%) and a control diet containing 5% soybean oil were hand-fed to triplicate groups of fish (average weight, $9.7{\pm}0.3g$) for 8 weeks. Survival, specific growth rate, feed efficiency and protein efficiency ratio of fish were not affected by dietary EPA and DHA levels or ratios. Also, the dietary treatment had no significant effect on the lipid and protein contents of muscle and whole body of fish. A corresponding increase in the EPA and DHA contents of fish occurred with increasing EPA and DHA levels in their diets. Our results suggest that juvenile olive flounder require a dietary EPA level of approximately 0.32% in the presence of 0.74% DHA for suitable survival and growth, and that EPA and DHA levels in fish muscle can increase to as much as 32% and 53%, respectively, of the total fatty acid content.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.2
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• pp.351-354
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• 2002

The objective of this study was to analyze fatty acid composition in lipids extracted from bullfrogs (Rana catesbeiana Shaw) inhabiting in Korea. Lipid contents in bullfrog legs and bodies were less than 1% (w/w, wet basis) and seasonal variation of the lipid contents was not observed. Lipids in bullfrog legs consisted of 26~31% (w/w) saturated fatty acids, 16~24% monounsaturated fatty acids, and 30~40% polyunsaturated fatty acids. Lipids in bullfrog bodies consisted of 23~28% saturated fatty acids, 29~44% monounsaturated fatty acids, and 16~30% polyunsaturated fatty acids. The major fatty acids in lipids extracted from bullfrogs were palmitic acid, oleic acid, and linoleic acid. Lipids in leg muscles contained 3~8% eicosapentaenoic acid (EPA) and 6~10% docosahexaenoic acid (DHA). Lipids in bodies had 1~3% EPA and 1~3% DHA.

• 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.

• Journal of Cancer Prevention
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• v.22 no.1
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• pp.1-5
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• 2017

Pancreatic cancer is a highly aggressive malignant tumor of the digestive system and radical resection, which is available to very few patients, might be the only possibility for cure. Since therapeutic choices are limited at the advanced stage, prevention is more important for reducing incidence in high-risk individuals with family history of pancreatic cancer. Epidemiological studies have shown that a high consumption of fish oil or ${\omega}3-polyunsaturated$ fatty acids reduces the risk of pancreatic cancers. Dietary fish oil supplementation has shown to suppress pancreatic cancer development in animal models. Previous experimental studies revealed that several hallmarks of cancer involved in the pathogenesis of pancreatic cancer, such as the resistance to apoptosis, hyper-proliferation with abnormal $Wnt/{\beta}-catenin$ signaling, expression of pro-angiogenic growth factors, and invasion. Docosahexaenoic acid (DHA) is a ${\omega}3-polyunsaturated$ fatty acid and rich in cold oceanic fish oil. DHA shows anti-cancer activity by inducing oxidative stress and apoptosis, inhibiting $Wnt/{\beta}-catenin$ signaling, and decreasing extracellular matrix degradation and expression of pro-angiogenic factors in pancreatic cancer cells. This review will summarize anti-cancer mechanism of DHA in pancreatic carcinogenesis based on the recent studies.

• Korean Journal of Community Nutrition
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• v.29 no.2
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• pp.144-155
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• 2024

Objectives: This study evaluated dietary intake and food sources of essential fatty acids in Korean adolescents. Methods: This study was comprised of 3,932 adolescents (9-18 years) who participated in the 2016-2021 Korea National Health and Nutrition Examination Surveys. Dietary intake and food sources of essential fatty acids, including alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and linoleic acid (LA) were evaluated using data obtained from one-day 24-hour dietary recall. The proportions of adolescents consuming ALA, EPA + DHA, and LA above or below the adequate intake (AI) of the 2020 Dietary Reference Intakes for Koreans were calculated. All statistical analyses accounted for the complex sampling design effect and appropriate sample weights. Results: The mean intakes of ALA, EPA, DHA, and LA among Korean adolescents were 1.29 g/day, 69.6 mg/day, 166.0 mg/day, and 11.1 g/day, respectively. Boys had higher intakes of all essential fatty acids compared to girls. By age group, adolescents aged 15-18 years showed lower intakes of EPA and DHA compared to adolescents in younger age groups. The 9-11-year-old adolescents had lower intakes of ALA and LA than older adolescents. The proportions of adolescents who consumed more than AI were 35.7% for ALA, 30.4% for EPA + DHA, and 41.5% for LA. Adherence to the AI for ALA did not differ by sex or age group, although boys showed a lower adherence to the AI for EPA + DHA than girls. Major food sources for ALA and LA were plant-based oils, mayonnaise, pork, and eggs. Mackerel was the most significant contributor to EPA and DHA intake (EPA, 22.6%; DHA, 22.2%), followed by laver, squid, and anchovy. Conclusions: The proportion of Korean adolescents who consumed EPA + DHA more than AI was low. Our findings highlight that nutrition education emphasizing an intake of essential fatty acids from healthy food sources is needed among Korean adolescents.

• ALGAE
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• v.32 no.1
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• pp.67-74
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• 2017

The heterotrophic dinoflagellate Oxyrrhis marina is known to produce high levels of docosahexaenoic acid (DHA) when fed on diverse algal prey. However, large-scale culturing of algal prey species is not easy and requires a large amount of budget, and thus more easily cultivable and low-cost prey is required. Dried yeast was selected as a strong candidate for an alternative prey in our preliminary tests. Thus, we explored the fatty acid composition and DHA production of O. marina fed on dried yeast and compared these results to those of O. marina fed on two algal prey species: the phototrophic dinoflagellate Amphidinium carterae and chlorophyte Chlorella sp. powder. O. marina fed on dried yeast, which does not contain DHA, produced the same high level of DHA as those fed on DHA-containing A. carterae. This indicates that O. marina is likely to produce DHA by itself regardless of prey items. Furthermore, the DHA content (and portion of total fatty acid methyl esters) of O. marina satiated with dried yeast, 52.40 pg per cell(and 25.9%), was considerably greater than that of O. marina fed on A. carterae (26.91 pg per cell; 15.7%) or powder of Chlorella sp. powder (21.24 pg per cell; 16.7%). The cost of dried yeast (approximately 10 US dollars for 1 kg dried yeast) was much lower than that of obtaining the algal prey (approximately 160 US dollars for 1 kg A. carterae). Therefore, compared to conventional algal prey, dried yeast is a more easily obtainable and lower-cost prey for use in the production of DHA by O. marina.

• Journal of Nutrition and Health
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• v.29 no.3
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• pp.267-277
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• 1996

Effect of DHA-rich fish oil on brain development and learning ability has been studied in Sprague Dawley rats. Female rats were fed experimental diets containing either corn oil fish oil at 10%(w/w) level throughout the gestation and lactation. Corn oil was added in fish oil diet to supply essential fatty acid at 2.3% of the calories. All male pups were weaned to the same diets of dams at 21-days after birth. Plasma fatty acid composition was analyzed for dams and pups at 21-days, 28-days and 22-weeks after birth. The analysis of DNA and fatty acid profile in the brain were undertaken at birth, 3, 7, 14, 21, 28 days and 22 weeks after birth and learning ability was tested at 18-20 weeks of age. Regardless of dietary fats, arachidonic acid(AA) and docosahexaenoic acid(DHA) were the principal polyunsaturated fatty acids in the brain. Rats fed CO diet showed a continouus increase of AA content in the brain from 10.9%(at birth) to maximum 15.3% level (14-days old), while the rars fed FO diet showed 78-79% of CO group throughout the period. Rats fed FO diet showed higher incorparation of DHA from 15.2% at birth to a maximum level of 18.5% at 140days, while the rats fed CO diet showed only 7.0% incorporation of DHA at birth and a maximum level of 11.1% at 21-days. Compared to CO group, FO group showed lower ratio of chol/PL and higher content of DHA in brain microsomal membrane, resulting in better membrane fluidity. Total amount of DNA per gram of brain was reached maximum level at 21 days in both groups. This would be a period of the cell proliferation during brain development. Overall, the rats fed fish oil diet showed a higher incorporation of DHA and membrane fluidity in the brain and better learning performances (p<0.05).