Potential sources of polyunsaturated fatty acids

All-Union Scientific-Research Institute of the Technology of Blood Substitute and Hormone Preparations, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 4, p. 592, July–August, 1988.     

A simplified method for analysis of polyunsaturated fatty acids

Background  

Analysis of fatty acid composition of biological materials is a common task in lipid research. Conventionally, preparation of samples for fatty acid analysis by gas chromatography involves two separate procedures: lipid extraction and methylation. This conventional method is complicated, tedious and time consuming. Development of a rapid and simple method for lipid analysis is warranted.     

Some aspects of the stereochemistry and nomenclature of polyunsaturated hydroxy fatty acids

When the D, L (but not the R, S) nomenclature is used, general laws are observed in the stereochemistry of lipoxygenase oxidation reactions and in the formation of epoxides from hydroperoxides of polysaturated hydroxy fatty acids. In both cases the formation of a C-O bond is coupled with the stereoselective elimination of a hydrogen atom, and the chiral and prochiral carbon atoms have identical configurations. The use of the D, L nomenclature in the polyenic hydroxy fatty acid series appears preferable to that of the R, S nomenclature.     

Some aspects of the stereochemistry and nomenclature of polyunsaturated hydroxy fatty acids

When the D, L (but not the R, S) nomenclature is used, general laws are observed in the stereochemistry of lipoxygenase oxidation reactions and in the formation of epoxides from hydroperoxides of polysaturated hydroxy fatty acids. In both cases the formation of a C-O bond is coupled with the stereoselective elimination of a hydrogen atom, and the chiral and prochiral carbon atoms have identical configurations. The use of the D, L nomenclature in the polyenic hydroxy fatty acid series appears preferable to that of the R, S nomenclature.A. L. Mndzhoyan Institute of Fine Organic Chemistry, Academy of Sciences of the Armenian SSR, Erevan. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 622–623, September–October, 1985.     

Dicranenones — A new class of C18 polyunsaturated fatty acids

In this review paper we consider questions of the occurrence in nature and the biosynthesis and total chemical synthesis of the dicranenones — new cyclopentanoid C₁₈ polyunsaturated fatty acids. A critical evaluation of the stereochemical assignments in this series of compounds is given. Institute of Bioorganic Chemistry, Belorussian Academy of Sciences, Minsk. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 607–622, November–December, 1992.     

尿素包合法分离蚕蛹油中多不饱和脂肪酸

蚕蛹是缫丝副产品,我国每年副产近20万吨干蛹[1].蚕蛹中油脂含量相当丰富,约占蚕蛹干基的25%～29%,且油脂总量的71.0%为不饱和脂肪酸,这些不饱和脂肪酸在人体内可合成二十碳五烯酸及二十二碳六烯酸,与鱼油中的EPA,DHA具有相似的抗衰老、健脑益智的功能,能维持正常的肾脏功能,治腰背疼痛、肌肉无力,预防动脉硬化、血脂升高等血栓疾病[2].     

Identification of novel n-4 series polyunsaturated fatty acids in a deep-sea clam, Calyptogena phaseoliformis

Novel fatty acids originated from the cold-seep clam Calyptogena phaseoliformis, collected from hydrothermal vents in the Japan Trench at a depth of 6354-6367 m, were determined by using gas chromatography-mass spectrometry analysis of the 4,4-dimethyloxazoline derivatives. The major fatty acids present in the C. phaseoliformis lipids belong to the n-4 family non-methylene interrupted polyunsaturated fatty acids (NMI-PUFA): 20:3n-4,7,15, 20:4n-1,4,7,15, and 21:3n-4,7,16, with significant levels of 20:2n-7,15 and 21:2n-7,16 as non-methylene interrupted n-7 dienes. Compared with the lipids of shallow-water clam Mactra chinensis, which contains photosynthetic n-3 PUFA, such as docosahexaenoic acid and icosapentaenoic acid, C. phaseoliformis might have an intrinsic mechanism in vivo so as to maintain the fluidity of the high-melting fatty acids in the membrane lipids by exogenous n-4 family PUFA adaptation as substitutes. Such special kinds of fatty acids are assimilated by the symbiotic chemosynthetic bacteria, which use geothermal energy and minerals from the cold-seep vents. Its unique fatty acid composition corresponding to the novel n-4 family NMI-PUFA markedly differs from those of the reported lipid compositions of other marine animals, which depend on the marine grazing food chain originating from phytoplankton. Thus, the present findings confirm a perfect and closed novel food chain in the cold-seep bivalve and in its symbionts, which is independent from the photosynthetic food chain.     

Analysis of polyunsaturated fatty acids in blood serum after fish oil administration.

Free and total fatty acids in the blood serum of patients with hyperlipoproteinemia have been analysed as their methyl esters by capillary gas chromatography using an FFAP column. In one-step reactions the free fatty acids in serum react with methanol-acetyl chloride (50:1, v/v) at 25 degrees C, the total fatty acids (free plus esterified) are transesterified with methanol-toluene-acetyl chloride (8:2:1, v/v) at 100 degrees C. The quantification of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is based on an internal standard (13,16,19-docosatrienoic acid) and on calibration standards. Under normal diet the concentrations of EPA and DHA are as follows (mean +/- S.D., n = 27): free EPA, 0.2 +/- 0.1 mg/dl; free DHA, 0.6 +/- 0.2 mg/dl; total EPA, 3.6 +/- 2.1 mg/dl; total DHA 11.4 +/- 3.1 mg/dl. Under a fish oil intake of 9 g per day, free and total EPA concentrations rise by ca. five- to six-fold, and free and total DHA concentrations by ca. two-fold.     

Chemical synthesis of deuterium-labeled and unlabeled very long chain polyunsaturated fatty acids

First syntheses of a deuterium-labeled very long C34-containing polyunsaturated fatty acid, 34:5n5, and three other unlabeled very long chain C30-32 containing polyunsaturated fatty acids are reported. These syntheses were achieved by coupling chemically modified C22- and C20-containing polyunsaturated fatty acids with carbanions derived from arylalkyl sulfones, followed by sodium amalgam-mediated desulfonylation.     

Enzymatic hydrolysis of anchovy oil: Production of glycerides enriched in polyunsaturated fatty acids

In an attempt to produce the polyunsaturated fatty acid (PUFA)enriched glycerides, commercially available Turkish anchovy oil (PUFA content of 27%), was hydrolyzed with 1,3-specificRhizomucor miehei lipase. After the hydrolysis, the triglyceride (TG), diglyceride (DG), monoglyceride (MG), and free fatty acid (FFA) composition of the reaction mixture was determined, and fatty acid components of these fractions were analyzed.R. miehei lipase released PUFA extremely slowly, resulting in their accumulation in the TG and DG fractions, especially in TG. The PUFA content in the glyceride mixture (including TG, DG, and MG) increased as hydrolysis progressed. The effects of operational parameters (pH, temperature, time, and enzyme concentration) on the extent of hydrolysis were investigated. Based on these results, optimal reaction conditions were established. At optimal conditions (pH 4.0, 35°C, 3 h, and enzyme concentration of 500 U/g oil), the level of PUFA in the glyceride mixture was raised to 40%. The individual TG and DG fractions contained 45 and 30% PUFA, respectively. Less than 2% of the total PUFA was lost in the FFA fraction.     

Syntheses of some polyunsaturated sulfur- and oxygen-containing fatty acids related to eicosapentaenoic and docosahexaenoic acids.

With the aim of enhancing selectively the beneficial biological effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) a number of polyunsaturated fatty acids containing sulfur or oxygen atoms in the chain has been synthesized starting from EPA and DHA, respectively. Oxidative degradation of these acids led to the corresponding aldehydes all-(Z)-3,6,9,12-pentadecatetraenal and all-(Z)-3,6,9,12,15-octadecapentaenal. Reactions with DBU converted these aldehydes quantitatively into the conjugated isomers (2E,6Z,9Z,12Z)-pentadecatetraenal and (2E,6Z,9Z,12Z,15Z)-octadecapentaenal, respectively. The four aldehydes were transformed by a sequence of reactions comprising reduction to the alcohols, halogenation and substitution with mercapto esters into the corresponding sulfur containing polyunsaturated fatty acid esters. The oxygen containing esters were prepared from the respective alcohol by boron trifluoride catalysed reaction with ethyl diazoacetate.     

Impact on lipid membrane organization by free branched-chain fatty acids

Here, we exploit the non-invasive techniques of solid-state NMR (nuclear magnetic resonance) and differential scanning calorimetry (DSC) to study the effect of free iso and ante-iso branched chain fatty acids (BCFAs) on the physicochemical properties of lipid membranes. Free fatty acids are present in biological membranes at low abundance, but can influence the cellular function by modulating the membrane organization. Solid state NMR spectra of dimyristoylphosphatidylcholine (DMPC) lipid membranes containing either free 12-methyltetradecanoic acid (a15:0) or free 13-methyltetradecanoic acid (i15:0), show significant differences in their impact on the lipid bilayer. Chain order profiles obtained by deuterium NMR on fully deuterated DMPC-d(67) bilayers revealed an ordering effect induced by both fatty acids on the hydrophobic membrane core. This behavior was also visible in the corresponding DSC thermograms where the main phase transition of DMPC bilayers-indicative of the hydrophobic membrane region-was shifted to higher temperatures, with the iso isomer triggering more pronounced changes as compared to the ante-iso isomer. This is probably due to a higher packing density in the core of the lipid bilayer, which causes reduced diffusion across membranes. By utilizing the naturally occurring spin reporters nitrogen-14 and phosphorus-31 present in the hydrophilic DMPC headgroup region, even fatty acid induced changes at the membrane interface could be detected, an observation reflecting changes in the lipid headgroup dynamics.     

Measurement of polyunsaturated fatty acids of myocardial lipids by high performance liquid chromatography

Summary This report describes a modified method for the separation and analysis of polyunsaturated fatty acids such as 20:4, 20:5, and 22:6, using HPLC. The results show that these fatty acids are well separated from the saturated acids. Since the unsaturated fatty acids elute earlier than saturated acids, and this method does not require the fractionation of free fatty acids using thin layer chromatography, a necessary step for the gas chromatographic analysis, the recoveries of polyunsaturated fatty acids were significantly higher as compared to those from gas chromatography. Furthermore, HPLC and gas chromatographic methods gave identical results for the acyl chain composition of phosphatidylserine. The advantages of using HPLC over gas chromatography in determining the acyl chain composition of free fatty acids and phospholipids are also discussed.     

Marine macroalgae analyzed by mass spectrometry are rich sources of polyunsaturated fatty acids

Algae from cold water (Canada) and warm water (China) were analyzed for their total lipid content, and for their fatty acid (FA) composition and content. The major findings are that FA from Canadian algae are generally richer in polyunsaturated FA (PUFA), with a higher n-3/n-6 FA ratio, and a higher degree of total unsaturation. The 18 C, 4 double bonds FA (18 : 4 stearidonic acid, morotic acid as synonym) was detected in greater amounts in cold water samples. The high levels of total PUFA, and especially of n-3 FA in Canadian algae, suggests their possible utilizations for nutritional purposes.     

溶剂量子化学特性对鱼油多不饱和脂酰甘油酯非水相酶促合成作用的影响

鱼油多不饱和脂酰甘油酯非水相酶促合成率与底物摩尔比例、反应温度、溶剂分子性质及溶剂系统中的最初水分含量有密切关系。溶剂分子的量子化学特性对非水相酶促酯化反应具有极为重要的影响。酯化率依溶剂分子最高占有轨道能量的增高及前沿轨道能差的减少而增加。溶剂分子电荷密度、静电势及前沿轨道系数对酯化率无显著影响。说明溶剂分子内不存在作用中心，溶剂分子主要是为非水相酶促酯化反应提供易于形成酶一底物电荷转移复合物的诱导场环境。