Stearidonic acid (18:4n‐3): Metabolism,nutritional importance,medical uses and natural sources

Stearidonic acid (SA, 18:4n‐3) is a polyunsaturated fatty acid (PUFA) that constitutes the first metabolite of α‐linolenic acid (ALA, 18:3n‐3) in the metabolic pathway leading to C_20–22 PUFA, such as eicosapentaenoic acid (EPA, 20:5n‐3), and docosahexaenoic acid (DHA, 22:6n‐3), which recently have received much attention because of their various physiological functions in the human body. Recently, several studies indicated that dietary SA increased EPA more efficiently than ALA. Thus, vegetable oils containing SA may become a dietary source of n‐3 fatty acids that is more effective in increasing tissue n‐3 PUFA concentrations than the current ALA‐containing vegetable oils. Nevertheless, few SA sources occur in nature, although there are still a large number of species untested to date. SA has been detected in variable amounts in several species of algae, fungi and animals tissues, but the seeds of some plant families seem to be better sources of SA, especially Echium (Boraginaceae) species. This work reviews the nutritional significance, medical uses and natural occurrence of SA.     

Maternal High‐Fat‐Diet Programs Rat Offspring Liver Fatty Acid Metabolism

In offspring exposed in utero to a maternal diet high in fat (HF), we have previously demonstrated that despite similar birth weights, HF adult offspring at 6 months of age had significantly higher body weights, greater adiposity, and increased triacylglycerol (TAG) levels as compared to controls. We hypothesized that a maternal HF diet predisposes to offspring adiposity via a programmed increase in the synthesis of monounsaturated fatty acids in the liver and hence increased substrate availability for liver TAG synthesis. We further hypothesized that programmed changes in offspring liver fatty acid metabolism are associated with increased liver expression of the lipogenic enzyme stearoyl‐CoA desaturase‐1 (SCD‐1). Female rats were maintained on a HF diet rich in monounsaturated fatty acids (MUFA) prior to and throughout pregnancy and lactation. After birth, newborns were nursed by the same dam, and all offspring were weaned to control diet. Plasma and liver fatty acid compositions were determined using gas chromatography/mass spectrometry. Fatty acid C16 desaturation indices of palmitoleic/palmitic and (vaccenic + palmitoleic)/palmitic and the C18 desaturation index of oleic/stearic were calculated. Liver protein abundance of SCD‐1 was analyzed in newborns and adult offspring. Plasma and liver C16 desaturation indices were decreased in HF newborns, but increased in the adult offspring. Liver SCD‐1 expression was increased in the HF adult offspring. These data show that the maternal HF diet during pregnancy and lactation increases offspring liver SCD‐1 protein abundance and alters the liver C16 desaturase pathway.     

“Click Chemistry” for the Simple Determination of Fatty‐Acid Uptake and Degradation: Revising the Role of Fatty‐Acid Transporters

Fatty acids (FAs) have numerous functions in all living organisms, ranging from structural roles and energy production to the biosynthesis of secondary metabolites. Because of the high energy content of exogenous FAs, their acquisition is central of metabolism, and several biological systems are known, although their precise roles are not yet entirely clear. We investigated the roles of FadD (CoA ligase) and FadL (FA transporter) in different bacterial strains by using an improved version of click‐chemistry‐assisted labelling of azido‐FAs. The high sensitivity of this method allows a direct and precise assessment of FA metabolism, and is thus far better suited than growth experiments. Our results show that although FA activation is indeed essential for FA degradation, their transport can be independent of transporters like FadL.     

Lipid‐derived monomer and corresponding bio‐based nanocomposites

Fatty acid based monomer and corresponding hybrid polymer layered silicate nanocomposites have successfully been prepared by using in situ polymerizations. The hybrid materials were prepared by adding different ratios of nanoclay during free radical homopolymerization of 2‐(acryloyloxy)ethyl stearate (AOES) monomer and copolymerization of AOES with styrene. AOES monomer was synthesized by treating stearic acid with 2‐hydroxyethyl acrylate. The formation of AOES monomer, homopolymer and copolymer was confirmed by ¹H NMR spectroscopic analysis. Further analysis and characterization of the nanocomposites were carried out by XRD, transmission electron microscopy, AFM and attenuated total reflectance Fourier transform infrared spectroscopy. TGA of the polymer nanocomposites was also carried out to evaluate their thermal stability, while flammability tests were conducted to investigate the effect of layered silicate on flame retardancy. Nanofiller addition into the polymer matrix substantially improved the thermal properties and fire retardancy of the composites. © 2016 Society of Chemical Industry     

Thermoplastic Polyurethane Elastomers with Aliphatic Hard Segments Based on Plant‐Oil‐Derived Long‐Chain Diisocyanates

Novel plant‐oil‐derived long‐chain (C₁₉ and C₂₃) α,ω‐diisocyanates, optionally in combination with the corresponding long‐chain diols, provide entirely aliphatic hard segments in segmented thermoplastic polyurethane elastomers (TPUs), with carbohydrate‐based poly(trimethylene glycol) soft segments. Compared to materials based on a mid‐chain monomer analog, phase separation is higher due to an increased flexibility of the aliphatic segments. Although melting points are slightly lower than for HDPE, the long‐chain TPU's solid‐state structure is still dominated by hydrogen‐bonding.     

Synthesis of regioisomerically pure triacylglycerols containing n‐3 very long‐chain polyunsaturated fatty acids

There is growing scientific evidence that consumption of n‐3 very long‐chain polyunsaturated fatty acids (n‐3 VLC‐PUFA) helps in brain and eye development, and protects against a range of common degenerative diseases. This has provided the impetus to the scientists to develop new and renewable sources for these important fatty acids so that the food industry is able to produce and market products fortified with n‐3 VLC‐PUFA. The bioactive efficacy and stability of food products containing n‐3 VLC‐PUFA may be determined not only by the amount of n‐3 VLC‐PUFA present but also by the positional distribution of these acids within the triacylglycerol (TAG) molecules (regiopurity). Studies of the effects of positional distribution on the functionality of n‐3 VLC‐PUFA containing oils have been hampered by a general lack of pure TAG regioisomers for experimentation. This paper reviews methods that have been used for the synthesis of TAG regioisomers containing n‐3 VLC‐PUFA, with special reference to those in which one n‐3 VLC‐PUFA occurs in combination with two long‐chain saturated acids.     

Thraustochytrids as an alternative source of omega‐3 fatty acids,carotenoids and enzymes

Currently the most common microalgae used for commercial production of omega‐3 fatty acids are marine derived, particularly from family members of Thraustochytriaceae and Crypthecodiniaceae. Thraustochytrids are marine heterotrophic fungi like microorganisms known to produce several commercially interesting biotechnological compounds including omega‐3 fatty acids such as docosahexaenoic acid (DHA), docosapentaenoic acid (DPA) and eicosapentaenoic acid (EPA), carotenoids, sterols, exopolysaccharides and enzymes. Therefore, exploring the potential of thraustochytrids has much to offer to the commercial production of bioactive compounds. In response to growing demand for omega‐3 fatty acids, various isolation, fermentation and lipid recovery strategies have been developed in recent years.     

Fully renewable limonene‐derived polycarbonate as a high‐performance alkyd resin

Limonene‐derived polycarbonate‐based alkyd resins (ARs) have been prepared by copolymerization of limonene dioxide with CO₂, catalysed by a β‐diiminate zinc–bis(trimethylsilyl)amido complex, and subsequent chemical modification with soybean oil fatty acids using triphenylethylphosphonium bromide as the catalyst. This quantitative partial modification was realized via epoxy–carboxylic acid chemistry, affording ARs with higher oil lengths, lower polydispersities and higher glass transition temperatures (T_g) in comparison to a conventional polyester AR based on phthalic acid, multifunctional polyol pentaerythritol and soybean fatty acid. The novel limonene polycarbonate AR and the conventional polyester AR were evaluated as coatings and both the physical drying (without the presence of the oxidative drying accelerator Borchi® Oxy Coat) and chemical curing (with Borchi® Oxy Coat) processes of these coatings were monitored by measuring the König hardness and complex modulus development with time. A better performance was obtained for the alkyd paint containing polycarbonates modified with fatty acids (FA‐PCs), which showed a faster chemical drying, a higher König hardness and a higher T_g in coating evaluation, demonstrating that the fully renewable FA‐PCs are promising resins for alkyd paint applications. © 2019 Society of Chemical Industry     

Dietary saturated and omega‐3 fatty acids affect growth and fatty acid profiles of Malaysian mahseer

The current study was conducted to determine optimal levels of dietary saturated fatty acids (SFA), n‐3 PUFA and to study potential n‐3 sparing effect of dietary SFA for Malaysian mahseer Tor tambroides. Juvenile T. tambroides were fed four trial diets with similar basal composition but different oil mixtures in a 2 × 2 factorial experimental design for 10 weeks. The two factors were the levels of dietary SFA and the levels of dietary n‐3 PUFAs. Growth performance and fatty acid profile of tissues were analyzed at the end of the experiment. Significant differences in growth performance were observed among treatments, and fish fed the diet low in n‐3 and high in SFA showed the best growth performance. T. tambroides fed the high n‐3 diets showed a significantly higher (p<0.05) muscle total n‐3 PUFA content compared to fish fed the low n‐3 diets. The highest 22:6 n‐3 and total n‐3 PUFA content of the liver were also observed in fish fed the low n‐3 and high SFA diet. However, the significant interaction (p<0.05) between dietary SFA and n‐3 PUFA levels was observed for the total n‐3 PUFA content of both muscle and liver tissues, suggesting an n‐3 sparing action by dietary SFA. The results of this study suggest that 2.5% n‐3 PUFA in the diet of T. tambroides, with an SFA to n‐3 ratio of 15.3, is sufficient to provide the best growth performance and to retain the n‐3 content of tissues. Practical applications: The continuous increase of world population and growth of aquaculture industry put severe pressure on the marine resources such as fish oil and fishmeal. Here we show that fish oil can be substituted with palm oil, a cheaper and more available source of oil in tropical countries, in the diet of Malaysian mahseer without a reduction of growth. Moreover, palm oil as a source of SFA may spare omega‐3 in the fish tissues. Omega‐3 is an essential fatty acid for humans as final consumer of edible fish.     

Phase‐Changeable Fatty Acid Available for Temperature‐Regulated Drug Release

This paper describes a mixture of fatty acids that is available for temperature‐controlled release of drugs. The mixture consists of two fatty acids with different melting points. At a specific composition, the mixture represents a single melting point of 38–40 °C which is slightly above the normal human body temperature. To demonstrate its use in the temperature‐regulated release, this study fabricates fatty acid‐incorporated polymer fibers containing dye‐loaded polymer particles in their core. Below the melting point of the mixture, it will be in a solid state to restrict the passing of dye loaded in the core whereas the dye can be released instantly through the generated pores at a temperature slightly higher than the melting point. The release profiles of the dye can be further manipulated by varying the amount of the mixture contained in the fibers and the composition of the mixture.

     

Zeolite‐catalyzed isomerization of oleic acid to branched‐chain isomers

Branched‐chain (bc) saturated fatty acids (SFA) have potential as oleochemical intermediates since they have better oxidative stability than linear unsaturated fatty acids (UFA) and have better low‐temperature properties than linear SFA. Previous studies in converting UFA to bc‐FA using clay catalysts have resulted in only modest yields and conversions. Recent reports, however, have suggested that certain zeolites can be effective catalysts for converting UFA to bc‐FA in higher yields and conversions. In this work, we examined the scope and potential of the zeolite‐catalyzed synthesis of bc‐FA starting from readily available monounsaturated linear FA. Our results show that common UFA such as oleic acid can be converted to bc‐isomers using modified Ferrierite zeolite catalysts with high conversions (98%) and high selectivity (85%) and that the zeolite catalysts are reusable for at least three cycles. The positions of branching (methyl) on the FA chain were determined from the GC‐MS spectra of the picolinyl esters of the bc‐FA.     

Fatty fish intake,n‐3 fatty acids and self‐rated health in middle‐aged adults

Background – Since n‐3 fatty acids, abundant in fatty fish, may improve health, we raised the question whether self‐reported intake frequency of fatty fish (FF) might be related to the percentage of n‐3 fatty acids in serum phospholipids (PL‐n‐3), and also to self‐rated health (H). Design – The study followed a cross‐sectional design. Methods – In the cross‐sectional Oslo Health Study, PL‐n‐3 were determined in 121 middle‐aged ethnic Norwegians and 102 immigrants from the Indian subcontinent and correlated with FF and H. Logistic regression was used to study the relationship between PL‐n‐3 and H (dichotomized, i.e. Poor vs. Good health). Results – FF correlated positively with PL20:5n‐3 (PL‐EPA, r = 0.467, p <0.001) and PL22:6n‐3 (PL‐DHA, r = 0.499, p <0.001), and negatively with PL20:4n‐6 (PL‐AA, r = –0.350, p = 0.001). H was positively associated with PL‐EPA (r = 0.321, p <0.001) and PL‐DHA (r = 0.275; p <0.001), but negatively with PL‐AA (r = –0.220, p = 0.001). The odds ratio for reporting Poor vs. Good health was significantly higher in subjects with low levels of PL‐EPA (OR = 1.49; 95% confidence interval = 1.17–1.89, p = 0.001), persisting after adjusting for sex, physical activity, ethnicity and length of education. Conclusion – The intake frequency of fatty fish is related to n‐3 fatty acids in the serum phospholipids, and to self‐rated health.     

Transition‐metal trifluoromethane‐sulphonates‐recyclable catalysts for the synthesis of branched fatty derivatives by Diels‐Alder reactions at unsaturated fatty esters

Diels‐Alder reactions of conjugated linoleic acid ethyl ester (1) with different quinones and with a variety of α/βunsaturated aldehydes and ketones are described in this paper. Using Sc(OTf)₃ or Cu(OTf)₂ as catalysts the reactions can be carried out at 25—40 °C with good yields. For the first time in oleochemistry it is possible to prepare Diels‐Alder cycloadditions with catalyst concentrations of 10 mol‐% instead of stoichiometric amounts of Lewis acids. Furthermore, the reaction time was partly shortened drastically. The catalyst Sc(OTf)₃ can be removed by a simple extraction of the organic layer with water. After evaporation of the aqueous phase to dryness the catalyst can be reused without loss of yield.     

Fatty acid and 3‐hydroxy fatty acid composition of two Hypericum species from Turkey

The fatty acid compositions of flowering tops of Hypericum perforatum L. and Hypericum retusum Aucher (Guttiferae) were analyzed by gas chromatography and gas chromatography‐mass spectrometry. The major components were C16:0 (24.87%), C18:3 n‐3 (21.94%), 3‐OH‐C18:0 (18.46%) and 3‐OH‐C14:0 (14.22%) for H. perforatumL. and 3‐OH‐C14:0 (28.29%), C18:0 (16.47%) and C16:0 (14.17%) for H. retusum Aucher. Besides widespread plant fatty acids, 3‐hydroxy fatty acids, namely 3‐hydroxytetradecanoic acid (3‐OH‐C14:0) and 3‐hydroxyoctadecanoic acid (3‐OH‐C18:0) were also obtained.     

ω‐Imidazolyl‐ and ω‐Tetrazolylalkylcarbamates as Inhibitors of Fatty Acid Amide Hydrolase: Biological Activity and in vitro Metabolic Stability

Fatty acid amide hydrolase (FAAH) is a serine hydrolase that terminates the analgesic and anti‐inflammatory effects of endocannabinoids such as anandamide. Herein, structure–activity relationship studies on a new series of aryl N‐(ω‐imidazolyl‐ and ω‐tetrazolylalkyl)carbamate inhibitors of FAAH were investigated. As one result, a pronounced increase in inhibitory potency was observed if a phenyl residue attached to the carbamate oxygen atom was replaced by a pyridin‐3‐yl moiety. The most active compounds exhibited IC₅₀ values in the low nanomolar range. In addition, investigations on the metabolic properties of these inhibitors were performed. In rat liver homogenate and in porcine plasma, the extent of their degradation was shown to be strongly dependent on the kind of aryl residue bound to the carbamate as well as on the length and type of the alkyl spacer connecting the carbamate group with the heterocyclic system. With the aid of esterase inhibitors it was shown that in porcine plasma, carboxylesterase‐like enzymes and paraoxonase are involved in carbamate cleavage. Moreover, it was found that highly active pyridin‐3‐yl carbamates reacted with albumin, which led to covalent albumin adducts.     

Characterization of Trimethylolpropane‐Based Biolubricant

The oxidative stability index (OSI) of fatty acid methyl esters (FAME) and trimethylolpropane (TMP) esters or TMPE produced from five vegetable oils (Brassica rapa L., Linum usitatissimum L., Zea mays L., Brassica napus L., Camelina sativa L.) are compared. The highest stability is observed in vegetable oils while the processed products are less stable. The major causes in loss of OSI are attributed to excess FAME in the crude product and the loss of natural antioxidants due to refinement with silica and celite. The low‐temperature flow properties of TMPE produced from four different vegetable oils (B. juncea L., L. usitatissimum L., B. rapa L., and C. sativa L.) are investigated by proton nuclear magnetic resonance (¹H‐NMR). The T2 relaxations of different TMPE are measured to observe how the mobility of oil changed as temperature decreased. Increased oil mobility (represented by T2) is correlated with rising temperature. The Gaussian widths of the singlet in ¹H‐NMR spectra of each oil demonstrated increased molecular mobility as temperature increased. Extrapolation of the relation of T2 signals of these four oils indicates that T2 approached zero between 232 K and 239 K, suggesting the molecular motion leading to a T2 relaxation has largely ceased. Practical Applications: The OSI is determined for four vegetable oils as well as the product FAME and TMPE. The vegetable oils are more stable than their products. The loss of natural antioxidants during purification of FAME and TMPE contributes to the lower OSI compared to vegetable oil. The low‐temperature flow behavior of TMP‐based biolubricants is determined between 238 K and 298 K using T2 relaxation. As temperature decreases, a singlet resonance in ¹H‐NMR spectra attributed to TMP protons broadens until it disappears. The results suggest that the log of the spin‐spin relaxation time is linearly correlated with rising temperature and oil mobility.