Transition-metal Catalyzed Oxidative Cleavage of Unsaturated Fatty Acids

The oxidative cleavage of the C? C-bond converts unsaturated fatty acids to carboxylic and dicarboxylic acids. The only method currently used in oleochemistry is ozonolysis. The high energy consumption of ozonolysis makes a transition-metal catalyzed alternative with a cheaper secondary oxidant attractive. Here we report new methods for ruthenium-, rhenium- and tungsten-catalyzed oxidations with peracetic acid and hydrogen peroxide. Whereas the direct oxidative cleavage of internal C? C-bonds still lacks selectivity, two-step reactions are feasible. The first possibility is to convert natural, internal unsaturated fatty acids to ω-unsaturated ones. These ω-unsaturated fatty acids can be cleaved by Ru/acac)₃/CH₃COOOH or Re₂O₇/H₂O₂ with yields up to 80 %. In the second two-step procedure the fatty acid first is hydroxylated and the diol is cleaved: the overall yield for this method is 80 %, too.     

尿素包合法分离橡胶籽油中的多价不饱和脂肪酸

用尿素包合法从橡胶籽油混合脂肪酸中分离多价不饱和脂肪酸 ,用正交设计实验法对分离工艺进行研究 ,其最佳分离条件是 :原料配比为m(混合脂肪酸 )∶m(尿素 )∶m(乙醇 ) =1 0 0∶1 5∶1 8,回流时间 12 0min。经一次尿素包合法分离即可得到多价不饱和脂肪酸质量分数大于90 %的产品 ,实验收率大于 35 %     

Distribution of Glycolipid and Unsaturated Fatty Acids in Human Hair

It has been recognized that human hair lipids play crucial roles in the integrity of cells and matrices, while the details of distribution and structure of the minor lipids are hardly known. Here we investigated the lipids at the hair surface, at the interface between cuticle and cortex and in the interior of hair (cortex, medulla and melanin granules). Hair lipids and fatty acids and their metabolites were detected and characterized by using infrared spectroscopy and several mass spectrometry techniques (FTIR, ToF–SIMS, GCMS, and ESI–MS). As a result, it was found that unsaturated fatty acids were present more in the cortex of hair than at the hair surface. At the interface between cuticle and cortex, it is suggested that steryl glycoside‐like lipids containing N‐acetylglucosamine were present, and contributing to the adhesion between the cuticle and cortex of hair. Oxidative metabolites derived from integral fatty acids such as linoleic and alpha‐linolenic acids were found in the hair bulb and melanin granules. Especially the oxidative metabolites of alpha‐linolenic acid were integrated into the lipids non‐covalently and tightly bound to melanin granules (namely, melanin lipids) and suggested as being involved in the biosynthetic processes of melanosome.     

不饱和脂肪酸及其衍生物环氧化研究进展

综述了环氧化不饱和脂肪酸及其衍生物的制备工艺和实验方法,包括过氧酸环氧化法、卤代醇环氧化法、过氧化氢或有机过氧化氢环氧化法、分子氧环氧化法。其中使用过氧酸的方法是工业上使用最为广泛的,可以采用酸或者酶作催化剂;而以过氧化氢为氧化剂的固体催化工艺是目前最有工业化前途的技术。并指出了开发新型、高效、绿色且廉价的催化体系仍是今后的研究方向。     

Hydroxy Sulfonated Fatty Acid Esters as Surface Active Agents II: Surfactants from Individual Saturated and Unsaturated Fatty Acids

Hydroxy sulfonated fatty acid ester surfactants, having the general formula RCOOCH₂CHOHCH₂SO₃M (where M is alkali or other metal) have been synthesized from four saturated (C₁₂ to C₁₈) and four unsaturated (C₁₈?, C₁₈²?, C₁₈³? and ricinoleic) fatty acids. Comparative evaluation of their surface active properties as well as some analytical methods for determining their composition and their identification and separation have been described.     

用分子蒸馏器浓缩不饱和脂肪酸

Pharmaceutical oil is obtained from peanut oil by wiped film short path distiller(SPD).The concentration ofeffective unsaturated fatty acids in the pharmaceutical oil is more than five percentages,the evaporation rate is more than25%.The experiment results indicate that the optimum technology parameters for wiped film SPD are that feed flow rateis 131 mL/h,operation pressure is 0.1 Pa,agitation speed is 140 rmp,temperature of feed is 190℃and the best evapo-ration is 260℃.     

The Percentage of n-3 Highly Unsaturated Fatty Acids in Total HUFA as a Biomarker for Omega-3 Fatty Acid Status in Tissues

A blood biomarker of omega-3 fatty acid intake and tissue status could serve as a modifiable risk factor for cardiovascular disease. The percentage of omega-3 highly unsaturated fatty acid (HUFA ≥ 20 carbons and ≥3 double bonds) in the total HUFA pool (the n-3 HUFA score) was examined as a potential blood biomarker of omega-3 fatty acids in tissues. The fatty acid composition of total lipid extracts (TLE) and phospholipid (PL) fractions were determined for plasma and erythrocytes samples of human subjects (n = 20) and the n-3 HUFA score and the sum of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were compared. Omega-3 fatty acids in blood and tissues of rats (n = 31) and pigs (n = 48) were also determined and the associations were compared. The n-3 HUFA score is more consistent across plasma and erythrocytes, with strong correlations between TLE and PL in plasma (r = 0.93) and erythrocytes (r = 0.94). The n-3 HUFA score was less variable and blood levels correlated strongly with various animal tissues. The n-3 HUFA score is a useful blood biomarker that does not require the isolation of the PL class thereby supporting high throughput analyses. The strength of association between the n-3 HUFA score and disease risk needs to be examined.     

Palmitic Acid Lipotoxicity in Microglia Cells Is Ameliorated by Unsaturated Fatty Acids

Obesity and metabolic syndrome are associated with cognitive decline and dementia. Palmitic acid (PA) is increased in the cerebrospinal fluid of obese patients with cognitive impairment. This study was therefore designed to examine fatty acid (FA) lipotoxicity in BV2 microglia cells. We found that PA induced time- and dose-dependent decrease in cell viability and increase in cell death without affecting the cell cycle profile and that PA lipotoxicity did not depend on cell surface free fatty acid receptors but rather on FA uptake. Treatment with sulfosuccinimidyl oleate (SSO), an irreversible inhibitor of fatty acid translocase CD36, significantly inhibited FA uptake in BSA- and PA-treated cells and blocked PA-induced decrease in cell viability. Inhibition of ER stress or treatment with N-acetylcysteine was not able to rescue PA lipotoxicity. Our study also showed that unsaturated fatty acids (UFAs), such as linoleic acid (LA), oleic acid (OA), α-linolenic acid (ALA), and docosahexaenoic acid (DHA), were not lipotoxic but instead protected microglia against PA-induced decrease in cell viability. Co-treatment of PA with LA, OA, and DHA significantly inhibited FA uptake in PA-treated cells. All UFAs tested induced the incorporation of FAs into and the amount of neutral lipids, while PA did not significantly affect the amount of neutral lipids compared with BSA control.     

鱼油不饱和脂肪酸的自由基氧化规律

从东海小杂鱼鱼油中鉴定出43种脂肪酸,主要16种脂肪酸占总脂肪酸95．01％。测定了鱼油加入自由基后在不同的时间及不同光照条件下的脂肪酸的氧化规律,并进行分析发现无论在光照还是避光条件下所有不饱和脂肪酸都随着时间的推移,含量都有下降的趋势,说明不断的被氧化,特别是EPA、DHA被氧化的更快。在光照条件下鱼油中的脂肪酸氧化比在避光条件下要快。在实验过程中,通过在鱼油加入自由基后再加入不同的抗氧化剂,利用TBA值的测定,筛选出对鱼油中的脂肪酸氧化有较好的抗氧化性的各种抗氧化剂的有效浓度。同时可以发现4-己雷琐辛的抗氧化性最强,由于此实验中用的TBHQ是食品级的,因此BHA的抗氧化性比TBHQ强。并且对鱼油在添加抗氧化剂前后脂肪酸的自由基氧化规律进行比较。     

尿素包合法富集八月瓜籽中不饱和脂肪酸工艺研究

以八月瓜籽为原料,采用索氏法提取八月瓜籽中的籽油,利用尿素包合法对籽油中不饱和脂肪酸进行富集;以碘值为评价指标,采用单因素实验和星点设计响应面法对富集工艺进行优化;通过GC-MS对脂肪酸的成分进行分析,并确定其含量.结果表明:最佳富集工艺条件为尿素与95％乙醇质量体积比2.5:11、包合温度-24℃、包合时间24 h,...     

酶法酯交换过程中不饱和脂肪酸对其酰基位移的影响

酶法制备结构酯的过程中,由于酰基位移的发生而生成了副产品．并影响了产品质量。研究了Lipozyme IM和猪胰脂酶催化橄榄油与硬脂酸甲酯反应,油酸、亚油酸、亚麻酸的相对酰基位移率的比较。结果显示：双键越多酰基位移越小,猪胰脂酶催化时脂肪酸酰基位移程度大于Lipozyme IM。     

One-Step Concentration of Highly Unsaturated Fatty Acids from Tuna Oil by Low-Temperature Crystallization

Highly unsaturated fatty acids (HUFA), including eicosapentaenoic acid (EPA, 20:5n‐3), docosapentaenoic acid (DPA, 22:5n‐3 and 22:5n‐6) and docosahexaenoic acid (DHA, 22:6n‐3), play an important role in human health and nutrition. In this study, concentration of HUFA in free fatty acids (FFA) form by low‐temperature crystallization was investigated. For this purpose, tuna oil (7.1% EPA, 26.8% DHA) was first converted into corresponding FFA. Subsequently, crystallization conditions of various solvent types, the ratio of FFA to acetonitrile, operation temperature and crystallization time were optimized at a small scale of 2 g tuna oil fatty acids. Taking purity and yield into account, the optimum conditions were a 1:10 ratio of FFA to acetonitrile (w/v), ?60 °C, and 1 h. The optimal conditions resulted in concentrations of EPA, DHA and HUFA of 15.1, 58.4 and 79.6%, respectively, with corresponding yields of 61.5, 61.8 and 60.7%, respectively. Crystallization was carried out under the optimal conditions at a large scale of 200 g tuna oil FFA, and a similar concentration result was achieved. After evaporating away the solvent, the residual amount of acetonitrile met the US Pharmacopoeia requirement of <410 ppm. The process for enrichment of HUFA is readily scalable, effective and time‐saving.     

不饱和脂肪酸催化脱氧制备烃类燃料的研究进展

对不饱和脂肪酸催化脱氧制备烷烃燃料的研究进展进行了综述,主要介绍了不饱和脂肪酸的加氢脱氧法、脱羧法和脱羰法,并对各类脱氧反应中所用催化剂进行了归纳和总结。     

Analytical Problems in the Investigation of Unsaturated Acids Conversion II: Determination of Position Isomers,Conjugated Unsaturated Bonds and Composition of Fatty Acids

The paper discusses the methods of determination of the position of unsaturated bonds in a chain of acids, the determination of the sum of conjugated unsaturated bonds and the composition of the fatty acids. The position of unsaturated bonds in acids of modified oils may be determined most quickly by the method of pyrrolidide derivatives and determinations by the GLCMS method. The content of conjugated bonds had been determined by standardized method of UV spectrometry, and the composition of the fatty acids had been determined by gas chromatography.     

决明子中不饱和脂肪酸高效液相色谱重叠峰的解析

利用HPLC-ESI/MS技术及提取离子色谱(EIC)数据处理分析方法,在正离子模式下,决明子脂溶性成分中的不饱和脂肪酸以阳离子加合物[M+solvent+H]+或自身叠加的形式被检出。研究表明该法对未能完全分离的重叠峰进行解析,发现了重叠峰中含有亚麻酸的结构信息,得到了比较满意的结果。     

Membrane Fatty Acids as Pacemakers of Animal Metabolism

The recent discovery that the fatty acid composition of tissue phospholipids varies in a systematic manner among species has lead to the proposal that membrane fatty acid composition is an important determinant of the metabolic rate characteristic for each species. Endotherms (mammals and birds) have a basal metabolic rate (BMR) that is several times that of ectotherms and have more polyunsaturated membranes. In both birds and mammals, as species size increases there is a decrease in mass-specific BMR and a decrease in membrane polyunsaturation. Membrane-associated processes are significant components of BMR and important membrane proteins operate at much faster rates in species with high BMR than in those with low BMR. A series of “species-crossover” experiments show that the rate of this molecular activity is largely due to the nature of the membrane bilayer surrounding these membrane proteins such that polyunsaturated membranes are associated with fast membrane-associated processes. It is suggested that this influence is due to the physical properties that such polyunsaturated membranes possess. This has been called the membrane pacemaker theory of metabolism and provides a framework to understand factors such as the influence of diet on metabolism. It is noted that in the rat membrane fatty acid composition is a regulated parameter being more influenced by the balance between n-3 and n-6 polyunsaturates in the diet than it is by general diet content of saturated, monounsaturated and total polyunsaturated fats.     

Egg Yolk as Means for Providing Essential and Beneficial Fatty Acids

The new American Dietary Guidelines now recommend optimizing the types of fat consumed instead of reducing or eliminating fat from the diet. Chicken eggs are a means to deliver essential and beneficial human dietary fatty acids (FA), and can be staple component of healthy eating behavior. Additionally, polyunsaturated fatty acids can be increased in the avian egg yolk by simply incorporating selected lipid sources into the avian diet. Poultry feed rich in omega‐3 FA (omega‐3) has allowed commercialization of enriched eggs containing up to 600 mg of omega‐3. Conjugated linoleic acid (CLA) has also been used in the research setting to enrich eggs to provide a portion of the 3–4 g CLA day^?1 needed to promote weight loss to combat obesity. However, Americans consume only 50% of the omega‐3 recommended adequate intake, and average CLA consumption is under 600 mg day^?1. While a variety of foods are naturally rich in omega‐3, conventional sources of CLA are limited to bovine milk and meat, which do not provide enough CLA to produce clinical effects in a balanced diet. Since eggs and egg‐based products are common in the Western diet, eggs enriched with both omega‐3 and CLA using dietary additions to poultry feed may promote consumption of the recommended levels of these FA. This article reviews the design of poultry eggs with enhanced lipid profiles through dietary intervention, and discusses the future direction of enriched egg research.     

Metathesis of Unsaturated Fatty Esters

The development of a homogeneous catalyst (WCl₆Sn(CH₃)₄) for the metathesis of unsaturated fatty esters encloses new routes in fat chemistry. By these reactions an exchange of alkylidene moities takes place, thus methyl oleate is converted into 9-octadecene and 9-octadecenedioic dimethyl ester. The metathesis of poly-unsaturated esters leads to a much larger number of products, namely polyenes, mono- and dicarboxylic esters, and cyclopolyenes. Specially the formation of 1,4-cyclohexadiene is of great interest. The metathesis of unsaturated fatty oils and the cometathesis with alkenes are also possible. Reactants of technical purity with a low acid value (< 0.1) can undergo metathesis. The reaction is essentially thermoneutral; the distribution of products is statistical and no completion of the reaction occurs in one way or an other. Thus separation of reaction products and unconverted material is necessary. By the metathesis of mono-unsaturated esters this can be done by fractional crystallization. A review is given of these and other applications on account of the latest research development.