• Journal of Life Science
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• v.27 no.8
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• pp.965-973
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• 2017

Conjugated linoleic acid (CLA) is a group of positional and geometric isomers of linoleic acid with conjugated double bonds at C9,C11 and C10,C12 positions. Of possible CLA isomers, a naturally occurring CLA isomer is c9,t11-CLA which is produced from linoleic acid by linoleate isomerase from various rumen and lactic bacteria, and mushroom mycelia. Meanwhile, synthetically prepared CLA contained an equal amount of c9,t11-CLA and t10,c12-CLA isomers, and other isomers as minor constituents. CLA was firstly mentioned in 1939 during the elaidinization reaction of linoleic acid. Thereafter, CLA was not an attractant to scientists because it was not scientifically interested any more. However, since the anticarcinogenic action was driven from 7,12-dimethylbenz[a]anthracene (DMBA)-induced mouse skin carcinogenesis in 1987, CLA-related researches were drastically elevated, resulting in approximately 6,100 research papers in literature, so far. CLA exhibited the significant biological activities: anticarcinogenic, antidiabetic, antihypertensive, antiatherosclerotic, body-fat reducing, antioxidative, antiinflammatory, testosterone producing and other activities. Interestingly, two major CLA isomers, c9,t11-CLA and t10,c12-CLA, exhibited different biological activities. Meanwhile, t,t-CLA isomers which is minor constituent of chemically synthesized CLA from linoleic acid exhibited more potent anticarcinogenic activity in carcinogen-induced animal models and cancer cell lines than other CLA isomrs. In the present review, the significant biological activities of CLA were discussed along with historical studies of CLA since 1939.

• Journal of Veterinary Clinics
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• v.21 no.4
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• pp.336-342
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• 2004

The immunoenhancing effect of CLA isomers (CLA mixture, 10t-12c CLA, 9c-11c CLA, 9c-11c CLA, and 9t-11t CLA) on phagocytic activity of porcine peripheral blood leukocytes was examined. The phagocytic activities of peripheral blood mononuclear cells (PBMC) and polymorphonuclear cells (PMN) were analyzed by a flow cytometry system. The direct treatments of CLA isomers have no effect on phagocytosis of PMN as well as PBMC composed of approximately 10% monocytes and 90% lymphocytes. However, the phagocytic activities of PMN and monocyterich fraction from PBMC were remarkably enhanced by culture supernatant from PBMC treated with CLA mixture, 10t-12c CLA and 9c-11t CLA but not 9c-11c CLA and 9t-11t CLA. The phagocytic activity of PBMC was not enhanced by culture supernatant from PBMC treated with all CLA isomers. These results indicated that CLA isomers such as CLA mixture, l0t -12c CLA and 9c-11t CLA have an enhancing effect on phagocytosis of PMN and monocytes, which may be mediated through active humoral substances produced by CLA-stimulated PBMC. This study suggested that CLA stimulates PBMC to elaborate soluble factor(s), which may be an important mechanism for the enhancement of phagocytosis in non-specific immunity.

• Food Science of Animal Resources
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• v.21 no.1
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• pp.71-79
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• 2001

Emulsion-type sausages were manufactured to investigate the effects of CLA-vegetable oils and CLA-lard on quality of emulsion-type sausage. Each treatments replaced pork back fat with CLA-sesame oil (CLA-SO), CLA-lard (CLA-LD) and CLA-safflower seed oil (CLA-SSO) were stored during 1, 7, 14, 21 and 28 days at 4$^{\circ}C$. The changes in physico-chemical properties, thiobarbituric acid reactive substances(TBARS) and fatty acid composition of each treatments were measured during 1, 7, 14, 21 and 28 days at 4$^{\circ}C$. The pH values of all treatments significantly(p<0.05) decreased as storage time increased. Sausage products containing CLA-vegetable oils showed higher pH value than that of CLA-lard among the treatments. Color a*-value of CLA-SSO was higher than that of other treatments. During storage, TBARS values of treatments were significantly (p<0.05) increased, sausage products containing CLA-vegetable oils showed lower (p<0.05) TBARS value than CLA-lard, and TBARS of sausage products containing CLA-SSO was the lowest. This result indicated that CLA concentration in emulsion-type sausage did affect the lipid oxidation stability. Fatty acids composition was changed by addition of CLA-vegetable oils and CLA-lard. All kinds of fatty acids content decreased whereas CLA content extremely increased by replacement of CLA-vegetable oils and CLA-lard. The level of CLA content in CLA-vegetable oils was higher than CLA-lard. It may be concluded that emulsion-type sausage could be manufactured using CLA-vegetable oils as a pork fat substitutor without any negative effects on general components or physico-chemical properties.

• Journal of the Korean Society of Food Science and Nutrition
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• v.29 no.3
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• pp.389-394
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• 2000

CLA의 glycerol 유도체를 화학적으로 합성하였다. CLA-Cl(1.79 mmole), glycerol(0.6 mmole)과 pyridine (1.3mL)를 25C에서 8시간 반응시켰다. 이 반응물을 SGCC와 TLC를 이용하여 CLA의 glycerol 유도체를 분리하고 1H-NMR, 13C-NMR, IR, MS를 이용하여 분리된 유도체를 동정하였다. 이 실험조건하에서 사용된 CLA의 59.4%가 CLA의 glycerol 유도체(CLA-TG, CLA-DG, CLA-MG)로 전환되었다. CLA의 glycerol 유도체 중 CLA-TG는 52.1%, CLA-DG는 17.0%, CLA-MG는 30.9%였다.

• Journal of Animal Science and Technology
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• v.44 no.4
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• pp.427-442
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• 2002

Conjugated linoleic acid(CLA) is a collective term for a group of positional (c8, c10; c9, c11; c10, c12, and c11, c13) and geometric(cis,cis; cis,trans; trans,cis; and trans,trans) isomers of octadecadienoic acid (linoleic acid) with conjugated double bond system. CLA has been shown to have a variety of biological effects. Major effects of CLA on health, such as anti-cancer, anti-oxidation, anti-atherosclerosis and improving immuno-responses, might be derived or partially derived from the alternated lipid metabolism after CLA feeding. Most of studies on the effect of CLA on fat metabolism are concentrated on rats, mice, pigs and other mammals. The CLA inhibited carcinogen-induced neoplasia in several animal models and inhibited the proliferation of human malignant melanoma, colorectal and breast cancer cells and CLA reduced the atherosclerosis. Several studies have determined the antioxidant property of CLA; however, the property still remains controversial. Some of the studies have shown that CLA acted as an antioxidant, whereas some other studies have demonstrated that CLA might be a prooxidant. Several studies suggested that CLA could reduce fat accumulation in mammals. CLA was suggested to promote muscle growth and reduce fat deposition in mouse, and improve feed efficiency in rats. CLA has been shown to inhibit the activity of stearoyl-CoA reductase. CLA also reduced the content of arachidonic acid. Since arachidonic acid, and eicosapentaenoic acid (EPA) and docosahexenoic acid (DHA) are synthesized by different pathways, reducing the synthesis of arachidonic acid may not mean reducing that of EPA and DHA. Many sutdies have been shown biological effects of CLA. Therefore, further research is needed to answer the following questions: 1) how to synthesize the new CLA by new methods, 2) why CLA has shown biological effects, 3) how to increase CLA effects in animal products.

• Journal of Animal Science and Technology
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• v.45 no.6
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• pp.1047-1060
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• 2003

To investigate the effects of conjugated linoleic acid added diet feeding on CLA accumulation and quality characteristics of pork meat. The CLA used to add in diet was chemically synthesized by alkaline isomerization method with corn oil. Pigs were divided into 5 treatment groups(4 pigs/group) and subjected to one of five treatment diets(0, 1.25% CLA for 2 weeks, 2.5% CLA for 2 weeks, 1.25% CLA for 4 weeks and 2.5% CLA for 4 weeks, CLA diets; total fed diets) before slaughter. Pork loin were collected from the animals(110 kg body weight) slaughtering at the commercial slaughter house. Pork loin meat were aerobic packaged and then stored during 2, 5, 8, 11 and 14 days at 4$^{\circ}C$. Samples were analyzed for shear force value, texture, TBARS, fatty acid composition, cholesterol and CLA content. CLA treatment groups showed significantly(p〈0.05) higher shear force value compared to those of control group at 11, 14 days of cold storage. All treatments were decreased significantly as the storage period passed. There was a not significantly difference in texture between control and CLA treatment groups. All CLA treatment groups showed significantly(p〈0.05) lower TBARS value than the control. TBARS value was increased significantly during storage in all treatment. CLA treatment groups showed significantly(p〈0.05) lower cholesterol content compared to those of control group. As dietary CLA was increased in feed, the content of CLA was increased, but the control was almost not detected. The contents of CLA were not significantly changed during chilled storage for 14 days. In the change of fatty acid composition, the contents of oleic, linoleic and arachidonic were decreased by dietary CLA-supplementation, whereas the increase level of CLA-supplementation resulted in the higher palmitic and stearic acid. In all results, CLA could be accumulated in pork meat and its antioxidant capability has been indicated. It was suggested that dietary CLA-supplementation could be produced high quality pork.

• Preventive Nutrition and Food Science
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• v.5 no.2
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• pp.70-74
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• 2000

Most fatty acids in food matrices are triglyceride(TG) forms. Conjugated linoleic acid(CLA) produced from linoleic acid by microorganisms or chemicals is a free form. To apply the CLA to food systems, the TG containing CLA(designate CLA-TG) was synthesized by Lipozyme-catalyzed esterification method. An optimum reaction con-dition for the esterification of free CLA(FCLA) to glycerol by Lipozyme was determined as follows; Lipozyme(50mg) effectively catalyzed the esterification of CLA(500mg) to glycerol(1150mg) dissolved in isooctane (3ml) in a shaking incubator (200 rpm, 5$0^{\circ}C$) for 48 hr. Under the reaction condition, the resultant contained 52.4% CLA-TG as well as 31.1% Di-CLA-glycerol(CLA-DG), 7.6% mono-CLA-glycerol(CLA-MG), and 9.0% other CLA(un-reacted FCLA plus CLA dimer). These results suggest that the Lipozyme could be a useful enzyme for the production of CLA-TG to be employed in foods.

• Journal of Animal Science and Technology
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• v.45 no.2
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• pp.283-296
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• 2003

Emulsion-type sausages were manufactured to investigate the effects of CLA-vegetable oils and CLA-lard on quality characteristics of emulsion-type sausage. Each treatments replaced pork back fat with CLA-corn oil (CLA-CO), CLA-safflower seed oil (CLA-SSO) and CLA-lard (CLA-LD) were stored during 1, 7, 14, 21 and 28 days at 4$^{\circ}C$. The changes in physico-chemical properties, texture, thiobarbituric acid reactive substances (TBARS), fatty acid composition and CLA content of each treatments were measured during 1, 7, 14, 21 and 28 days at 4$^{\circ}C$. During storage, pH of control showed higher pH value than that of CLA-vegetable and CLA-lard treatments. The pH values of all treatments was significantly low at storage 14 days (p<0.05). The color L* and a*-value of all the treatments was not significantly changed with the storage periods. Color b*-value of CLA-treatments was higher than that of control during the storage period. Fatty acids composition was changed by addition of CLA-vegetable oils and CLA-lard. All kinds of fatty acids composition were decreased with CLA replacements than that of the control. Whereas linolenic acid content extremely increased by replacement of CLA-vegetable. CLA content of CLA-treatments was extremely increased than that of the control. The cohesiveness, springness, gumminess and brittleness of CLA-LD treatment was significantly higher (P<0.05) than that of the other treatments. The TBARS value of all treatments were significantly increased (P<0.05) as the storage period was passed. TBARS of sausage products containing CLA-CO was the lowest. Summing up the a forementioned results, emulsion-type sausage manufacturing with CLA-vegetable oil and CLA-lard was not affected in physico-chemical properties and texture characteristics. Also, it may be assumed that the high quality sausage can be manufactured with the extent of storage period and CLA accumulation.

• Preventive Nutrition and Food Science
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• v.5 no.2
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• pp.86-92
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• 2000

Conjugated linoleic acid(CLA) refers to a collective term of positional and geometric isomers of linoleic acid, which are different in their biological activities. The predominant isomer of CLA in animal tissues is cis-9, trans-11; smaller amounts of trans-10, cis-12 CLA isomers, CLA methyl ester (CLA-ME) was chemically syn-thesized from linoleic acid by the alkaline isomerization method. The synthetic CLA-ME, mainly composed of cis-9, trans-11 CLA and trans-10, cis-12 CLA, was dissolved in acetone, stored at 68$^{\circ}C$ for 1 day, and the supernatant(cis-9, trans-11 CLA-Me) was separated from the precipitate (trans-10, cis-12 CLA-Me). After the processes were repeated three times at -68$^{\circ}C$, the whole processes were repeated three times at -71$^{\circ}C$ in order to increase the purity of these two isomers. The cis-9, trans-11 CLA-Me and trans-10, cis-12 CLA isomers were further purified by the urea adduct. Purities of the cis-9, trans-11 CLA-Me and trans-10, cis-12 CLA-Me were 90.3 and 99.9%, respec-tively. This method could be employed for the preparation of a large quantity of highly purified cis-9, trans-11 CLA-Me or trans-10, cis-12 CLA-Me from synthetic CLA-Me.

• Journal of Veterinary Clinics
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• v.20 no.1
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• pp.1-6
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• 2003

Immunoenhancing effects of conjugated linoleic acid (CLA) isomers (l0t-l2c CLA, 9c-11t CLA, CLA mixture, 9c-11c CLA and 9t-11t CLA) on chemotactic activity of porcine peripheral blood polymorphonuclear cells (PMN) were examined. The chemotactic activity of PMN was evaluated by a modified Boyden chamber assay. CLA isomers at higher concentration of 50 to 200$\mu$M exhibited a low viability of cells by trypan blue exclusion. CLA isomers were used at concentration of 20uM showing no cytotoxic effect and high cell viability. CLA isomers themselves were not active or slight chemotactic for PMN. But culture supernatant from mononuclear cells (MNC) treated with 10t-12c CLA, 9c-11t CLA and CLA mixture except for 9c-11c. CLA and 9t-11t CLA enhanced remarkably chemotactic activity or porcine PMN PMN migration by culture supernatant from MNC treated with CLA mixture was found to be true chemotaxis by checkboard assay. This migration was also induced by porcine recombinant interleukin (rIL)-8. PMN chemotaxis caused both culture supernatant from MNC treated with CLA mixture and porcine rIL-8 was inhibited in a dose-dependent manner by addition of anti-porcine IL-8 polyclonal antibody. Therefore, these results strongly suggested that CLA (10t-12c CLA, 9c-11t CLA and CLA mixture) could stimulate porcine MNC to release and IL-8 like chemotactic activity.