羟基共轭亚油酸的绿色制备及物化性能研究

采用一步法绿色合成了羟基共轭亚油酸,主要从表面张力、乳化性能、泡沫性能、分散性能和Krafft点5个角度将其与蓖麻酸(RA)、共轭亚油酸(CLA)和亚油酸(LA)的钠盐进行了比较物化性能,并从结构方面分析了产生差别的原因,为其工业应用提供理论指导。     

三种抗坏血酸脂肪酸酯对共轭亚油酸的抗氧化性研究

本实验以葵花籽油为原料制备共轭亚油酸,以L-抗坏血酸、D-异抗坏血酸、棕榈酸和月桂酸为原料合成L-抗坏血酸棕榈酸酯、L-抗坏血酸月桂酸酯和D-异抗坏血酸棕榈酸酯,并研究上述酯对于共轭亚油酸的抗氧化效果。结果表明,添加0.02%、0.04%和0.08%的上述酯对于CLA具有明显且相似的的抗氧化作用,它们可以作为商品CLA的良好、安全的抗氧化剂。     

共轭亚油酸同分异构体对肥胖Zucker大鼠的脂肪肝中的类二十烷酸的影响

目的:检测使用共轭亚油酸(CLA)同分异构体后,Zucker大鼠肝脏中多种类二十烷酸水平以及探测与这些种类二十烷酸合成有关的酶的蛋白表达。方法:17周的雄性Zucker大鼠被随机分为对照组[瘦鼠对照组(lean control),和胖鼠对照组(fa/fa control)n=7]和治疗组[随机抽取的肥胖鼠(fa/fa 9,11CLA、fa/fa 10,12CLA),n=7],分别接受无CLA的对照饮食和加入0.4%(w/w)CLA的治疗饮食。8周后用高效液相质谱仪(HPLC/MS/MS)检测多种类二十烷酸水平;使用免疫印迹法(Westernblotting)探测与这些种类二十烷酸合成有关的酶的蛋白表达。结果:与对照组比较,t10,c12 CLA升高了肝组织中的白三烯4(LTB4)的水平(P<0.01)。然而,免疫印迹实验(Western blotting)显示,t10,c12 CLA(P<0.005)和c9,t11CLA(P<0.005)都抑制环氧合酶(COX2)的表达。与胖鼠对照组比较,瘦鼠对照组有较高的羟二十碳四烯酸(HODE)水平。结论:t10,c12 CLA减少脂肪肝里的总脂肪量,而抑制了COX2的蛋白表达、升高LTB4水平,两者对肝组织的影响,有待于组织学研究证实。胖鼠对照组有较低的13-HODE和9-HODE水平,与脂肪肝的饱和脂肪酸代谢酶的活性降低,引起亚油酸(LA)降低有关,不能反映血循环中的氧化应激状态。     

乳酸菌产共轭亚油酸研究现状

共轭亚油酸(conjugated linoleic acid, CLA)是十八碳二烯酸的异构体。通过食物摄入的CLA不能达到每日推荐摄入量,而CLA又具有减肥、抗癌、抗Ⅱ型糖尿病等多种生理功能,故CLA逐渐成为研究热点。与化学合成CLA相比,微生物合成CLA更具有优势。乳酸菌(lactic acid bacteria, LAB)具有安全性和益生功能,利用乳酸菌合成CLA是一个理想的途径。目前已发现多种产CLA乳酸菌,人们使用乳酸菌发酵油酸、牛乳、植物油合成CLA,并取得了良好的效果。亚油酸异构酶(linoleate isomerase, LAI)对乳酸菌合成CLA起重要作用,但其对乳酸菌合成CLA的作用机理还不明确。一些学者对乳酸菌合成CLA的中间产物进行了研究,发现乳酸菌合成CLA有多种中间产物。乳酸菌合成CLA的代谢机制目前尚不清楚。乳酸菌合成CLA对食品工业有重要意义,也为功能性食品的开发提供了新机遇。本文主要对CLA的生理功能、产CLA乳酸菌、乳酸菌合成CLA的底物、乳酸菌合成CLA的途径进行了概述。     

共轭亚油酸同分异构体对肥胖Zucker大鼠肾脏中的类二十烷酸的影响

目的:观察共轭亚油酸(CLA)的两种同分异构体对17w的肥胖Zucker大鼠的肾组织中的类二十烷酸水平的影响,并探测与这些类二十烷酸合成有关的酶的蛋白表达。方法:17w的雄性Zucker大鼠随机分为对照组[瘦鼠对照组(lean control)和胖鼠对照组(fa/fa control),n=7]和治疗组[随机抽取的肥胖鼠(fa/fa 9,11CLA和fa/fa 10,12 CLA),n=7],分别接受无CLA的对照饮食或加入0.4%(w/w)CLA的饮食。8w后,用高效液相质谱仪(HPLC/MS/MS)检测多种类二十烷酸水平、用免疫印迹法(Westernblotting)检测与这些类二十烷酸合成有关的酶的蛋白表达。结果:t10,c12 CLA增加了环氧合酶COX1的蛋白表达(P<0.05)、升高了内源性的TXB2水平(P<0.05)。COX1的升高与血柱素B2(TXB2)升高呈正相关。t10,c12 CLA降低了外源性的13-HODE和总的HODEs水平(P<0.001)以及外源性的15-HETE(P<0.01)、5-HETE(P<0.01)、8-HETE(P<0.05)和总外源性HETEs(P<0.05)。结论:t10,c12 CLA增加了COX1的蛋白表达,继而升高了TXB2水平,加重了肾组织损伤。t10,c12 CLA降低了外源性的15-HETE、5-HETE和8-HETE水平,由于同时降低了脂氧素,可能参与了对肾脏的损伤。     

共轭亚油酸合成原料的研究进展

共轭亚油酸(Conjugated Linoleic Acid,CLA)具有抗肿瘤、减少脂肪蓄积、调节机体免疫力、抗动脉粥样硬化、调节血糖血压、预防骨质疏松等多种生理活性,已经被广泛应用于医药、食品、保健品、化妆品等领域。由于CLA天然来源较少,以亚油酸为底物人工合成制备CLA成为了人们获取CLA的主要途径。本文系统介绍了游离脂肪酸、烷烃酯、甘油酯等不同形式的亚油酸及来源广泛、价格低廉的天然油脂在CLA生产中的运用,并综述了食品发酵中CLA的合成,为优化CLA原料利用、经济高效地获取CLA提供了参考。     

响应面优化脂肪酶催化酸解合成共轭亚油酸磷脂

采用商业化脂肪酶Lipozyme RM IM作为生物催化剂,催化共轭亚油酸(CLA,80％)和大豆磷脂( PC90)酸解反应合成富含CLA的结构磷脂.利用响应面分析方法研究了在正己烷溶剂体系中,底物摩尔比、酶用量、反应温度和反应时间对产物中CLA含量的影响.通过分析验证得到最佳反应条件为∶CLA与大豆磷脂的摩尔比6∶1,酶用量30％(以底物总质量计),反应温度48℃,反应时间64 h.在最佳反应条件下,产物中CLA的含量为24.18％.     

无溶剂体系酶法催化酸解合成共轭亚油酸甘油酯

采用商业化固定化酶Novozym 435作为生物催化剂,催化共轭亚油酸(CLA)和葵花籽油的酸解反应合成富含CLA的结构脂质(CLA-SL).研究了在无溶剂体系中,底物摩尔比、酶用量、体系含水量、反应温度和反应时间对产物中CLA含量和Sn-2位CLA含量的影响.结果表明,最佳反应条件为:CLA与葵花籽油摩尔比3 :1,酶用量10%,体系含水量1%,反应温度55 ℃,反应时间36 h.在最佳反应条件下,产物中的CLA含量和Sn-2位CLA含量分别为15.7%和2.73%.     

共轭亚油酸生物合成及其对肠道菌群影响的研究进展

共轭亚油酸(CLA)是一种人和动物自身无法合成但又不可缺少的脂肪酸,它具有抗癌、抗肥胖、抗动脉粥样硬化、抗糖尿病等潜在生理功能,被广泛用作食品营养补充剂。由于天然CLA来源较少、化学合成副产物较多,而利用乳酸菌生物合成的CLA结构单一且转化效率高,是一种有前景的合成方法。目前微生物将亚油酸(LA)转化为CLA的机制主要有2种,即以瘤胃微生物为主的生物氢化合成和乳酸菌为代表的多酶系合成。现有研究表明,CLA具有调节肠道菌群的作用,并指出其潜在生理功能可能与其对肠道微生态的影响密切相关。文章总结了CLA生物合成和影响因素,分析了CLA的生物合成机制以及其对肠道菌群的调节作用,为进一步筛选出高产CLA菌株和CLA的产业化应用提供理论依据。     

负载型固体酸催化合成椰子油脂肪酸酯的工艺研究

以新制负载型固体酸Zr(SO_4)_2-Ti(SO_4)_2/SiO_2催化合成椰子油脂肪酸1,6-己二醇酯为探针反应,优化带水剂种类及用量、酸醇物质的量比、催化剂用量、反应时间等椰子油脂肪酸酯的合成工艺条件。然后采用其他5种不同分子结构的醇合成了相应的椰子油脂肪酸酯,并通过FTIR表征以上6种合成产物的酯基结构。实验获得的优化合成工艺条件为:带水剂(甲苯)用量8 m L (相对于0. 02 mol 1,6-己二醇),酸醇物质的量比2. 5∶1,催化剂用量6%(以反应物总质量计),反应时间4. 5 h。在最佳条件下,椰子油脂肪酸1,6-己二醇酯合成反应的酯化率高达98. 6%。该固体酸催化剂催化合成椰子油脂肪酸一元醇酯的活性较高(酯化率99. 1%),但其对四元醇酯的催化活性相对较低(酯化率80. 3%)。随着醇分子中羟基个数的逐渐增加,固体酸的酯化催化活性降低;当醇羟基数相同时,醇分子支链减少或支链碳数减小都有利于提高固体酸的催化活性。     

Use of conjugated linoleic acid (CLA) enrichments to examine the effects of trans-8, cis-10 CLA, and cis-11, trans-13 CLA on milk-fat synthesis

Conjugated linoleic acid (CLA) supplements have typically been comprised of 4 isomers (trans-8, cis-10; cis-9, trans-11; trans-10, cis-12; and cis-11, trans-13 CLA). Abomasal infusion of pure isomers has shown that trans-10, cis-12 CLA is a potent inhibitor of milk-fat synthesis, whereas cis-9, trans-11 CLA has no effect. However, there appear to be additional fatty acids that inhibit milk-fat synthesis, and the objective of this study was to investigate the effects of additional CLA isomers present in CLA supplements. Four rumen fistulated Holstein cows (141+/-8 DIM, mean+/-SE) were randomly assigned in a 4 x 4 Latin square experiment. Treatments were abomasal infusion of (1) skim milk (negative control), (2) trans-10, cis-12 CLA supplement (positive control), (3) trans-8, cis-10 CLA supplement, and (4) cis-11, trans-13 CLA supplement. Treatments 2 through 4 were targeted to provide 4 g/d of the CLA isomer of interest. The trans-8, cis-10 CLA supplement had no effect on milk-fat yield, whereas the trans-10, cis-12 CLA supplement reduced milk-fat yield by 35%. The cis-11, trans-13 CLA supplement contained some trans-10, cis-12 CLA, and when data were compared to the positive control treatment group, it was obvious that cis-11, trans-13 CLA also had no effect on milk-fat synthesis. Milk-fat content of specific CLA isomers was significantly elevated within respective treatment groups. Milk yield, DMI, and milk protein yield were unaffected by treatment. Overall, trans-10, cis-12 CLA reduced milk-fat synthesis, whereas the other major isomers present in CLA supplements (trans-8, cis-10 CLA and cis-11, trans-13 CLA) had no effect.     

不同脂肪酸甲酯化方法对共轭亚油酸分析的影响

共轭亚油酸(CLA)是亚油酸的位置和几何异构体,因其具有多种生物学功能而成为人们关注的焦点。气相色谱法是分析CLA的一种简便而有效的方法,通过分析可以确定CLA的组成和含量。气相色谱法分析CIA先涉及脂肪酸的甲酯化,脂肪酸的甲酯化方法可分为3大类,酸催化、碱催化和三甲基硅重氮甲烷(TMS)法。一般游离型脂肪酸的甲酯化可采用酸催化或TMS法,而三甘油酯型的脂肪酸可采用酸催化或碱催化法。主要探讨3种甲酯化方法在不同结构的CLA气相色谱分析中的异同,通过薄层层析(TLC)和气相色谱(GC)测定,发现甲酯化过程中脂肪酸酯化的程度各不相同,CLA甲酯化后组成发生了异构化。结果表明,CLA经过酸催化法后得脂肪酸含量为73.34%,而TMS法为82.47%;酸催化法后反反CLA(tt-CLA)含量为24.66%。     

The effect of cooking on the fatty acid composition of longissimus muscle from beef heifers fed rations designed to increase the concentration of conjugated linoleic acid in tissue

Longissimus dorsi (LD) muscle from 60 Charolais crossbred heifers, aged for 14 days was used to investigate the effect of cooking on the content of PUFA and CLA fatty acids. Animals were offered a control diet of grass silage and concentrates (CO) or rations designed to enhance the concentration of CLA in tissue, i.e. unsupplemented grazed pasture (G), sunflower-oil supplemented grazing (SFG) or linseed-oil oil supplemented grazing (LSG). The SFG diet was the most effective for increasing the concentration of CLA but also caused the highest n-6/n-3 fatty acid ratio. There were no changes in the relative distribution of fatty acids upon cooking (140°C for 30min) and this procedure can be recommended because it preserves the nutritional value of the meat. It is concluded that irrespective of the change in the fatty acid composition of LD due to alteration in the diet of the cattle, cooking did not cause thermal degradation of PUFA, or thermal degradation or oxidative synthesis of CLA.     

Production and structural analysis of triacylglycerols containing capric acid and conjugated linoleic acid isomers obtained by enzymatic acidolysis

BACKGROUND: Structured lipids containing medium‐chain fatty acids have interesting applications as reduced‐calorie fats; moreover, conjugated linoleic acid (CLA) isomers have shown interesting biological properties. The aim of this study was to synthesize triacylglycerols (TAGs) containing capric acid in the sn‐1‐ and sn‐3‐ positions and CLA isomers in the sn‐2‐ position, using different commercial available lipases. RESULTS: The homogeneous CLA‐TAGs (Tri‐CLA) were chemically synthesized starting from glycerol and CLA isomers, 9‐cis,11‐trans and 10‐trans,12‐cis CLA. The acidolysis reactions of Tri‐CLA with capric acid were carried out at 55 °C for different times in hexane; after 96 h the acidolysis average yield was 65%. The best capric acid incorporation in total TAGs was obtained after 96 h with Lipozyme IM (56.6%). The results of structural analysis carried out on the obtained TAGs showed that both Novozyme 435 and anhydrous Lipozyme IM gave the best incorporation of capric acid in sn‐1(3)‐ positions (61.8%). However, anhydrous Lipozyme IM gave also the highest CLA percent content in sn‐2‐ position (73.2%). CONCLUSION: Anhydrous Lipozyme IM appears to be the more effective enzyme in acidolysis reactions to obtain structured TAGs containing CLA isomers in the central position and capric acid at external positions. Copyright © 2009 Society of Chemical Industry     

共轭亚油酸在凝固型酸乳中的应用研究

在脱脂乳中分别添加了含量为0.05%、0.10%、0.20%、0.30%、0.40%、0.50%的共轭亚油酸(CLA),发酵凝固后,通过测定添加不同含量的CLA的酸奶的特征指标,如酸度、黏度、保水力、口感等的变化,从而确定酸奶中CLA的最适合添加量。结果表明,CLA添加量为0.2%时,酸奶的产黏性特性、产酸特性、保水性以及口感风味较好。     

π-Complex formation of conjugated linoleic acid with iron

Conjugated linoleic acid (CLA) is known to have several beneficial biological effects in animal models, including anticarcinogenic and antiatherosclerotic effects, antiobesity, and antioxidant activity. However, reports of its antioxidant activities have been inconsistent. In this study, we investigated the possible occurrence of π-bonding between CLA and iron. CLA methyl ester was reacted with triiron dodecacarbonyl and confirmed to form π-complexes with iron tricarbonyl. This study may suggest the possible involvement of CLA in oxidation by way of interacting with iron.     

Effects of dietary supplementation of rumen-protected conjugated linoleic acid in dairy cows during established lactation

Short-term studies (< 5 d) involving abomasal infusion of a mixture of CLA isomers or pure trans-10, cis-12 CLA have demonstrated that supplements of conjugated linoleic acids (CLA) reduce milk fat synthesis during established lactation in dairy cows. Our objective was to assess longer term effects of supplementation during established lactation using a dietary supplement of rumen-protected CLA. Thirty Holstein cows were blocked by parity and received a dietary fat supplement of either Ca-salts of palm oil fatty acids (control) or a mixture of Ca-salts of palm oil fatty acids plus Ca-salts of CLA (CLA treatment). Supplements provided about 90 g/d of fatty acids and were topdressed on the TMR. The CLA supplement provided 30.4 g/d of CLA in which the predominant isomers were: trans-8, cis-10 (9.2%), cis-9, trans-11 (25.1%), trans-10, cis-12 (28.9%), and cis-11, trans-13 (16.1%). All cows were pregnant; treatments were initiated on d 79 of pregnancy (approximately 200 d prepartum) and continued for 140 d until dry off. Twenty-three cows completed the study; those receiving CLA supplement had a lower milk fat test (2.90 versus 3.80%) and a 23% reduction in milk fat yield (927 versus 1201 g/d). Intake of DM, milk yield, and the yield and content of true protein and lactose in milk were unaffected by treatment. Milk fat analysis indicated that the CLA supplement reduced the secretion of fatty acids of all chain lengths. However, effects were proportionally greater on short and medium chain fatty acids, thereby causing a shift in the milk fatty acid composition to a greater content of longer-chain fatty acids. Changes in body weight gain, body condition score, and net energy balance were not significant and imply no differences in cows fed the CLA supplement in replenishment of body reserves in late lactation. Likewise, maintenance of pregnancy, gestation length, and calf birth weight were unaffected by treatment. Overall, feeding a dietary supplement of rumen-protected CLA to pregnant cows over the last 140 d of the lactation cycle resulted in a marked reduction in milk fat content and yield, and a shift in milk fatty acid composition, but other milk components, DMI, maintenance of pregnancy, and cow well-being were unaffected.     

影响乳制品中共轭亚油酸(CLA)含量的因素

概述了共轭亚油（CLA）的形成方式、影响乳制品中CLA含量的因素及如何提高乳中CLA含量的方法。动物的种类、饲料的成分、喂养方式、季节等对原料乳产生的影响．以及加工方法、贮存条件、发酵菌种等对乳制品中CLA的含量的影响。     

Growth inhibition of osteosarcoma cell MG-63 by a mixture of trans,trans conjugated linoleic acid isomers: possible mechanistic actions

ABSTRACT:  The growth inhibitory effect of a mixture of t,t conjugated linoleic acid isomers ( t,t CLA) was investigated in the human osteosarcoma cell MG-63, with references to c 9, t 11 and t 10, c 12 CLA isomers. The t,t CLA effectively induced a cytotoxic effect in a time-dependent (0 to 6 d) and concentration-dependent (0 to 40 μM) manner, as compared to the reference and control treatments. The apoptosis and cell cycle related parameters were measured on the cells treated with 40 μM t,t CLA for 4 d. Flow cytometric analysis revealed that the t,t CLA treatment effectively increased the proportion of apoptotic cells with a low DNA content (sub G0/G1) and a marked loss of cells from the G0/G1 phase of the cell cycle, relative to other treatments. The occurrence of the characteristic morphological changes and DNA fragmentation confirmed the apoptosis. The level of Bax protein was increased, whereas the Bcl-2 expression was reduced. In addition, cytochrome c was released from the mitochondria into the cytosol, and the activation of caspase-3 led to the cleavage of poly (ADP-ribose) polymerase (PARP). Moreover, the composition of linoleic and arachidonic acids in membrane was decreased by increase in t,t CLA. These findings suggest that t,t CLA incorporation in membrane activates a mitochondria-mediated apoptosis pathway that can enhance the antiproliferative effect of t,t CLA in the osteosarcoma cells.