Synthesis of Sodium (+)-(12S,13R)-Epoxy-cis-9-octadecenyl Sulfonate from Vernonia Oil

A water-soluble, foaming epoxyalkene sulfonate, sodium (+)-(12S,13R)-epoxy-cis-9-octadecenyl sulfonate, was synthesized from vernonia oil (VO) by a series of simple reactions that include transesterification, metal hydride reduction, tosylation, and S_N2 reactions. Conversion of VO into vernonia oil methyl esters (VOME) using sodium methoxide was quantitative. Subsequent reduction of VOME with lithium aluminum hydride yielded (+)-(12S,13R)-epoxy-cis-9-octadecenol (94%), along with minor amounts of hexadecenol, octadecenol, cis-9-octadecenol, and cis-9,12-octadecandienol. The (+)-(12S,13R)-epoxy-cis-9-octadecenol, was tosylated with p-toluenesulfonyl chloride to give (+)-(12S,13R)-epoxy-cis-9-octadecenyl tosylate at 96% yield. Iodination of the tosylate with sodium iodide and subsequent S_N2 reaction with sodium sulfite afforded (+)-(12S,13R)-epoxy-cis-9-octadecenyl sulfonate (63% yield). This study demonstrates the ability to produce an epoxyalkenyl sulfonate, belonging to a class of anionic surfactants, from VO without destroying the epoxy functionality in the (+)-(12S,13R)-epoxy-cis-9-octadecenyl moiety of VO. The critical micelle concentration of the synthesized sulfonate was also determined.     

Determining Ethyl Esters in Fish Oil with Solid Phase Microextraction and GC–MS

The long-chain polyunsaturated fatty acids (PUFA) found in fish oil, specifically eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) play an important part in human health. As a result, fish oil supplements are commonly consumed by people around the world. Supplements in the form of triacylglycerols (TAG) can be sold at a premium price, compared to those in the ethyl ester (EE) forms. Producers of TAG supplements require a simple, rapid method to determine the authenticity of their raw material. Here, we describe a method to quantify EE in fish oil using solid phase microextraction headspace analysis and GCMS. Despite the variation in linear ranges of the calibration curves with volatility of the EE, 30 individual FA were quantified including common saturated FA such as palmitic and stearic acid, as well as longer chain PUFA, such as EPA and DHA. The method was then applied to three commercial fish oils in the TAG form and two of the products were found to contain EE, with one containing EE above 1.5% w/w, indicating that contamination had occurred. With growing consumer interest in fish oil products, the method proposed here will help resolve future issues of authenticity in fish oils.     

Differentiation of Fish Oils According to Species by <Superscript>13</Superscript>C-NMR Regiospecific Analyses of Triacyglycerols

The aim of this study was to use ¹³C-nuclear magnetic resonance (NMR) regiospecific analyses of triacylglycerols to distinguish fish oils from different fish species for authentication purposes. ¹³C-NMR data of muscle lipids from Atlantic salmon (Salmo salar L.), mackerel (Scomber scombrus) and herring (Clupea harengus) were obtained, and the distribution of omega-3 polyunsaturated fatty acids between the sn-1,3 and sn-2 glycerol chains calculated from the carbonyl region. The results show that there were significant differences in the sn-2 position specificity of the fatty acids 22:6n-3, 20:5n-3 and 18:4n-3 among the species investigated. The most pronounced difference was that herring had a higher proportion of its 22:6n-3 in the sn-2 position compared to the two other species. Principal component analysis of data points in the carbonyl-region showed that there were also differences in the level and regiospecific distribution of monounsaturated/saturated fatty acids, which made it possible to distinguish oils of these three species solely from the carbonyl region of ¹³C-NMR spectra.     

Plasma Lipids,Lipoprotein Metabolism and HDL Lipid Transfers are Equally Altered in Metabolic Syndrome and in Type 2 Diabetes

Metabolic syndrome (MetS) refers to states of insulin resistance that predispose to development of cardiovascular disease and type 2 diabetes (T2DM). The aim was to investigate whether plasma lipids and lipid metabolism differ in MetS patients compared to those with T2DM with poor glycemic control (glycated hemoglobin > 7.0). Eighteen patients with T2DM, 18 with MetS and 14 controls, paired for age (40–70 years) and body mass index (BMI), were studied. Plasma lipids and the kinetics of a triacylglycerol-rich emulsion labeled with [³H]-triolein ([³H]-TAG) and [¹⁴C]-cholesteryl esters ([¹⁴C]-CE) injected intravenously followed by one-hour blood sampling were determined. Lipid transfers from an artificial nanoemulsion donor to high-density lipoprotien (HDL) were assayed in vitro. Low-density lipoprotein (LDL) and HDL cholesterol (mg/dl) were not different in T2DM (128 ± 7; 42 ± 7) and MetS (142 ± 6; 39 ± 3), but triacylglycerols were even higher in MetS (215 ± 13) than in T2DM (161 ±11, p < 0.05). Fractional clearance rate (FCR, in min¹) of [³H]-TAG and [¹⁴C]-CE were equal in T2DM (0.008 ± 0.018; 0.005 ± 0.024) and MetS (0.010 ± 0.016; 0.006 ± 0.013), and both were reduced compared to controls. The transfer of non-esterified cholesterol, phospholipids and triacylglycerols to HDL was higher in MetS and T2DM than in controls (p < 0.01). Cholesteryl ester transfer and HDL size were equal in all groups. Results imply that MetS is equal to poorly controlled T2DM concerning the disturbances of plasma lipid metabolism examined here, and suggest that there are different thresholds for the insulin action on glucose and lipids. These findings highlight the magnitude of the lipid disturbances in MetS, and may have implications in the prevention of cardiovascular diseases.     

Lipid characterization of an arachidonic acid-rich oil producing fungus Mortierella alpina

Mortierel a alpina has been considered as the most effective producer of arachidonic acid (ARA)-rich oil. It was found that several methods could improve the percentage of ARA in total lipids successful y, as they activated the desaturation system on the endoplasmic reticulum. Additionally, in M. alpina the ARA exists in several forms, such as triacylglycerol (TAG), and diacylglycerol (DAG). These forms are caused by different acyltransferases and they determine the nutrient value of the microbial oil. However, few works revealed de-tailed fatty acid distribution among lipid classes, which to some extent impeded the accurate regulation in ARA accumulation. Herein, this paper gives information on the accumulation process of main lipid classes and the changes of fatty acid composition in these lipids during ARA accumulation period in M. alpina. The result dem-onstrates that TAG was the dominant component of the total lipids, and it is the main form for ARA storage. The ARA enrichment stage occurred during 168–192 h when the amount of total lipids maintained steady. Further analysis indicated that the newly formed ARA-TAG might come from the incorporation and modification of sat-urated and monounsaturated fatty acids in other lipid classes. This work could be helpful for further optimization of ARA-rich TAG production.     

Triacylglycerol Production in the Snow Algae Chlamydomonas nivalis under Different Nutrient Conditions

Eukaryotic microalgae have been known for high competency in the accumulation of triacylglycerol (TAG), a representative class of storage lipid. The snow algal species, Chlamydomonas nivalis, is a unique green eukaryotic microalga that can grow and survive in a wide range of temperatures. Although a few metabolomic studies of C. nivalis were conducted, no study has reported on TAG accumulation in C. nivalis. Herein, the present work aimed to investigate TAG production in C. nivalis under nutrient-starved conditions at 22 °C. Compared to phosphorus starvation, C. nivalis under nitrogen starvation showed a less severe growth defect, greater capacity for TAG production, and simple acyl composition in TAG enriched with 18:1. These features suggest that C. nivalis may be a significant model species to investigate glycerolipid metabolism for basic and applied research.     

Effects of Lipid Structure Changed by Interesterification on Melting Property and Lipemia

Interesterification or the randomization reaction changes fatty acid positional distribution and solid fat content of fats, which may consequently affect fat absorption and metabolism. It is well established that saturated fatty acids in the sn‐2 position of triacylglycerols (TAG) have better digestibility and lower postprandial chylomicron clearance compared to those in the sn‐1,3 positions in animal experiments. TAG structure is also shown to affect fasting lipid level and atherosclerosis in animals, but fat interesterification it has been shown to not affect fasting lipid level in human adults. However, its effect on postprandial responses is controversial. In this review, the complex results of studies of interesterification and lipemia were briefly discussed. More importantly, the confounding of two factors that are both changed by interesterification, TAG structure and solid fat content as the main limitation on understanding how interesterification affects lipemia is emphasized. Separation of the two factors is possible using paired fats as demonstrated. This paper also discusses some intriguing effects of fats having saturated fatty acids in the sn‐2 position and the need for future research.     

Electron microscopic visualization of fatty acids in tissues

Long-chain fatty acids are important structural and metabolic functions in tissues. Fatty acids are derived from triacylglycerol-rich particles in capillaries (chylomicrons and very-low-density lipoproteins) and from triacylglycerol stored in cells (lipid droplets) by the hydrolytic activity of tissue lipases. The identification and localization of fatty acids in tissues has been considered difficult to obtain by using conventional ultrastructural techniques. However, structural findings from our studies on fatty acid transport in tissue became interpretable due to the use of many overlapping techniques. We present here these ultrastructural techniques developed to study fatty acids in tissues and review data which demonstrate lipase activity and fatty acid production from triacylglycerol in aldehyde-fixed tissue. Accumulations of fatty acid in tissue are present as lamellar structures with periodicity of 40–50 Å in sections of resin-embedded tissue and as hydrated myelin figures in freeze fracture replicas of unfixed and fixed tissue. Finally, a new method, using the ionization properties of fatty acids combined with freeze fracture, locates these amphipathic molecules to leaflets of membrane bilayers.     

Characterization of Wheat Germ Oil in Terms of Volatile Compounds,Lipid Composition,Thermal Behavior,and Structure

In this study, the volatile compounds, lipid composition, thermal behavior, and structure of wheat germ oil were analyzed. Forty-four volatile compounds, mainly alcohols, esters, alkenes, and aldehydes, were isolated by headspace solid phase micro extraction. The major constituents were found to be hexanal (15.97%), 2-methyl-2-butene (10.43%), 2,4-heptadienal (8.53%), and limonene (6.83%). The oil was rich in unsaturated fatty acid (83.45%), especially in linoleic acid (64.82%), and there were 75.49% unsaturated fatty acid distributed in Sn-2 position. The main content of unsaponifiable matters was sterol, especially β-sitosterol (64.64%). The thermogravimetric analysis results showed one major regime of weight loss over a temperature range of 280–500°C and an exothermic behavior was observed by the differential scanning calorimetry data.     

Investigating the effect of starting mode on food fat gel layer formation on cold surfaces

In a previous study, Huang et al. (2012) employed a spinning disc apparatus to study deposition of fats on cooled stainless steel surfaces using model solutions of tripalmitin in non-crystallising paraffin. The apparatus was modified to give more accurate estimation of the test surface temperature, allowing the surface temperature and shear stress to be manipulated independently. The effect of different starting modes, simulating various situations which arise in pipelines, was studied. When fouling is induced by a step change in the test surface temperature, the presence of a subcooled surface promotes the rapid formation, initially, of a gel layer, followed by a period of linear fouling, and eventually falling rate fouling behaviour. When fouling is driven by a change in concentration the initial gel formation step is absent. The linear fouling regime was relatively insensitive to temperature, shear stress and starting mode for the conditions studied here. In the falling rate regime, the rate was determined by the deposit/solution interface temperature, following normal growth kinetics. At low tripalmitin concentrations, of 2.5 wt.%, sigmoidal growth behaviour was observed, which is attributed to the wall shear stress being initially high enough to disrupt the gel. As time proceeded, the gel increased in strength and was able to grow as before.