Optimization of Synthetic Conditions for the Preparation of Dihomo-γ-Linolenic Acid from γ-Linolenic Acid

Orthogonal experiments were employed to optimize the correlated parameters of reduction, sulfonation, substitution and hydrolysis. These reactions were used to convert γ-linolenic acids into dihomo-γ-linolenic acids (DGLA). For the reduction, the best reaction conditions were at 35 °C for 4.5 h with LiAlH₄ and γ-linolenic acid (in the ratio of 40 g:100 g); for the sulfonation, reaction at 29 °C for 3.5 h with 150 g γ-linolenic alcohol and 65 mL mesyl chloride, then the water phase being extracted with dichloromethane (3 × 100 mL); for the substitution, the reaction at 80 °C for 2.5 h with metallic sodium and sulfonate (at a ratio of 8 g:100 g); and for the hydrolysis, reaction at 80 °C for 2.5 h with NaOH and dihomo dioate (at a ratio of 50 g:100 g). The four reactions gave yields that exceeded 90% for each step. Finally, crystallization and decarboxylation provided DGLA in an overall yield of 60% and >95% purity.     

Maintenance of Arachidonic Acid and Evidence of Δ5 Desaturation in Cats Fed γ-Linolenic and Linoleic Acid Enriched Diets

Cats have limited Δ6 desaturase activity. However, γ-linolenate (GLA) feeding may by-pass the Δ6 desaturase step allowing arachidonate (ARA) accumulation via Δ5-desaturation. Alternatively, high dietary linoleate (LNA) may induce limited Δ6 desaturase also resulting in ARA accumulation. Fatty acid profiles were determined after feeding high LNA, high GLA, or adequate LNA diets. Adult female cats (n = 29) were assigned to one of three groups and fed for 8 weeks. Plasma samples were collected at weeks 0, 2, 4 and 8 for plasma triacylglycerol (TAG), total cholesterol (TC), lipoprotein (LP), and plasma and red blood cell membrane phospholipid fatty acid determinations. Time, but no diet, effects were observed for TAG, TC, and LP fractions at weeks 2 and 4 with significant increases likely due to increased dietary fat. However, all values were within feline normal limits. The GLA diet resulted in increased dihomo-γ-linolenic acid (DGLA) and ARA as early as week 2, supporting a ∆5 desaturase. Further evidence of Δ5 desaturase was found at high dietary LNA with the appearance of a novel fatty acid, 20:3 ∆7, 11, 14, apparently formed via ∆5 desaturation and chain elongation of LNA. However, Δ6 desaturase induction at high dietary LNA concentration was not observed. Cats are able to maintain plasma and red blood cell ARA when fed a practical diet containing GLA using what appears to be an active Δ5 desaturase enzyme.     

Synergism of α-Linolenic Acid, Conjugated Linoleic Acid and Calcium in Decreasing Adipocyte and Increasing Osteoblast Cell Growth

Whole fat milk and dairy products (although providing more energy compared to low- or non-fat products), are good sources of α-linolenic acid (ALA), conjugated linoleic acid (CLA) and calcium, which may be favorable in modulating bone and adipose tissue metabolism. We examined individual and/or synergistic effects of ALA, CLA and calcium (at levels similar to those in whole milk/dairy products) in regulating bone and adipose cell growth. ST2 stromal, MC3T3-L1 adipocyte-like and MC3T3-E1 osteoblast-like cells were treated with: (a) linoleic acid (LNA):ALA ratios = 1–5:1; (b) individual/combined 80–90 % c9, t11 (9,11) and 5–10 % t10, c12 (10,12) CLA isomers; (c) 0.5–3.0 mM calcium; (d) combinations of (a), (b), (c); and (e) control. Local mediators, including eicosanoids and growth factors, were measured. (a) The optimal effect was found at the 4:1 LNA:ALA ratio where insulin-like growth factor-1 (IGF-1) and IGF binding protein-3 (IGFBP-3) production was the lowest in MC3T3-L1 cells. (b) All CLA isomer blends decreased MC3T3-L1 and increased MC3T3-E1 cell differentiation. (c) 1.5–2.5 mM calcium increased ST2 and MC3T3-E1, and decreased MC3T3-L1 cell proliferation. (d) Combination of 4:1 LNA:ALA + 90:10 % CLA + 2.0 mM calcium lowered MC3T3-L1 and increased MC3T3-E1 cell differentiation. Overall, the optimal LNA:ALA ratio to enhance osteoblastogenesis and inhibit adipogenesis was 4:1. This effect was enhanced by 90:10 % CLA + 2.0 mM calcium, indicating possible synergism of these dietary factors in promoting osteoblast and inhibiting adipocyte differentiation in cell cultures.     

The Health Promoting Properties of the Conjugated Isomers of α-Linolenic Acid

The bioactive properties of the conjugated linoleic acid (CLA) isomers have long been recognised and are the subject of a number of excellent reviews. However, despite this prominence the CLA isomers are not the only group of naturally occurring dietary conjugated fatty acids which have shown potent bioactivity. In a large number of in vitro and in vivo studies, conjugated α-linolenic acid (CLNA) isomers have displayed potent anti-inflammatory, immunomodulatory, anti-obese and anti-carcinogenic activity, along with the ability to improve biomarkers of cardio-vascular health. CLNA isomers are naturally present in high concentrations in a large variety of seed oils but can also be produced in vitro by strains of lactobacilli and bifidobactena through the activity of the enzyme linoleic acid isomerase on α-linolenic acid. In this review, we will address the possible therapeutic roles that CLNA may play in a number of conditions afflicting Western society and the mechanisms through which this activity is mediated.     

Physicochemical Properties of Lipase-Catalyzed Interesterified Fat Containing α-Linolenic Acid

Two substrate blends (8:6:6 and 6:6:9, by weight) of anhydrous butterfat (ABF), palm stearin (PS), and flaxseed oil (FSO) were interesterified by immobilized lipases. The reaction was carried out in the absence of solvent at 60 °C for 24 h in a 1-L tank stirred-batch type reactor. In terms of equivalent carbon number (ECN) of triacylglycerol (TAG), the areas of ECN 36-38 (from FSO) and ECN 48-50 (from PS) decreased during the interesterification while ECN 42–46 increased with increasing reaction time. As interesterification time increased, the decreased enthalpy (?H), peak temperature (T _P) and transition range were observed. After short path distillation, interesterified fat (IF) was produced in which α-linolenic acid contents (ALn, mol%) of the 8:6:6 and 6:6:9 IF were 15.7 and 21.7%, respectively. Tocopherol, cholesterol and phytosterol contents in each IF were significantly reduced after short path distillation. In this study, hardness of 6:6:9 IF and 8:6:6 IF were 217 and 800 g/cm², respectively. After interesterification, short spacing at 4.6 Å disappeared or weakened, indicating that the predominant polymorphic form had changed from the β form to the desirable crystalline structure of the β′ form.     

17β-Estradiol Increases Liver and Serum Docosahexaenoic Acid in Mice Fed Varying Levels of α-Linolenic Acid

Docosahexaenoic acid (DHA) is considered to be important for cardiac and brain function, and 17β-estradiol (E2) appears to increase the conversion of α-linolenic acid (ALA) into DHA. However, the effect of varying ALA intake on the positive effect of E2 on DHA synthesis is not known. Therefore, the objective of this study was to investigate the effects of E2 supplementation on tissue and serum fatty acids in mice fed a low-ALA corn oil-based diet (CO, providing 0.6 % fatty acids as ALA) or a high ALA flaxseed meal-based diet (FS, providing 11.2 % ALA). Ovariectomized mice were implanted with a slow-release E2 pellet at 3 weeks of age and half the mice had the pellet removed at 7 weeks of age. Mice were then randomized onto either the CO or FS diet. After 4 weeks, the DHA concentration was measured in serum, liver and brain. A significant main effect of E2 was found for liver and serum DHA, corresponding to 25 and 15 % higher DHA in livers of CO and FS rats, respectively, and 19 and 13 % in serum of CO and FS rats, respectively, compared to unsupplemented mice. There was no effect of E2 on brain DHA. E2 results in higher DHA in serum and liver, at both levels of dietary ALA investigated presently, suggesting that higher ALA intake may result in higher DHA in individuals with higher E2 status.     

Lymphatic Transport of α-Linolenic Acid and Its Conversion to Long Chain n-3 Fatty Acids in Rats Fed Microemulsions of Linseed Oil

In the present study we evaluated the uptake of ALA and its conversion to EPA + DHA in rats given linseed oil (LSO) in native form or as a microemulsion in whey protein or in lipoid. In a single oral dose study in which rats maintained on rodent pellets deficient in ω-3 fatty acids were intubated with 0.35 g LSO in lipoid, the amount of ALA present in lymph was increased reaching a maximum concentration of 16.23 mg/ml at 2.5 h. The amount of ALA present in lymph was increased to a maximum level of 10.95 mg/ml at 4 h in rats given LSO as a microemulsion in whey protein. When LSO was given without emulsification, the amount of ALA present in lymph was found to reach a maximum level of 7.08 mg/ml at 6 h. A similar result was observed when weaning rats were intubated with 0.15 g of LSO per day for a period of 60 days. Higher levels of ALA by 41 and 103 % were observed in lymph lipids of rats given microemulsions of LSO in whey protein and in lipoid respectively as compared to rats given LSO without pre-emulsification. Very little conversion of ALA to EPA and DHA was observed in lymph lipids but higher amounts of EPA + DHA was observed in liver and serum of rats given LSO in microemulsion form. This study indicated that ALA concentration in lymph lipids was increased when LSO was given in microemulsion form in lipoid and further conversion to EPA and DHA was facilitated in liver and serum.     

Oral Administration of Dihomo-γ-Linolenic Acid Prevents Development of Atopic Dermatitis in NC/Nga Mice

Disorders of the metabolism of essential fatty acids (EFAs) are related to atopic dermatitis (AD). Concentrations of dihomo-γ-linolenic acid (DGLA), an EFA, in the serum of AD patients are lower than those in healthy volunteers. Recently we developed a fermented DGLA oil, and examined whether oral administration of DGLA prevents development of dermatitis in NC/Nga mice, which spontaneously develop human AD-like skin lesions. NC/Nga mice were fed a diet either containing or not containing DGLA for 8 weeks under in air-uncontrolled conventional circumstances. Clinical skin severity scores were significantly lower in mice fed DGLA than in mice not fed it. Scratching behavior and plasma total IgE levels were also reduced in the DGLA group, in association with histological improvement. DGLA suppressed clinical severity of skin lesions dose-dependently, with an increase in DGLA contents in phospholipids of skin, spleen, and plasma. Discontinuation of DGLA administration resulted in the onset of dermatitis and a decrease in DGLA contents in skin, spleen, and plasma. These findings indicate that oral administration of DGLA effectively prevents the development of AD in NC/Nga mice, and that DGLA in phospholipids is a compound of key importance in the development and prevention of dermatitis.     

Lipase-Catalysed Enrichment of γ-Linolenic Acid from Evening Primrose Oil in a Solvent-Free System

The enrichment of γ-linolenic acid (GLA) was carried out in a solvent-free system by lipase-catalysed esterification of free fatty acids from evening primrose oil (EPO-FA) and 1-butanol (BtOH). The lipase employed to conduct this study was a free preparation of Candida rugosa. Variables evaluated were: substrate molar ratio (1:4, 1:6, 1:8, 1:10 and 1:12, EPO-FA:BtOH), temperature (10, 20, 30, 40, 50 and 60 °C), and enzyme loading (5, 10, 15 and 20 %, based on the total weight of substrates). GLA was highly enriched in the non-esterified fatty acid fraction since C. rugosa showed very low selectivity for this fatty acid. We were able to increase the content of GLA to ca. 70 wt.% under the following optimal conditions: 30 °C, 10 % enzyme loading and a 1:10 molar ratio (EPO-FA:BtOH), after 24 h. An additional set of experiments was conducted whereby the amount of water was controlled by addition of molecular sieves to the reaction mixture. The latter experiments produced a higher GLA concentrate (83.74 wt.%), under the optimal conditions described above and by adding 10 % molecular sieves (based on the total weight of substrates) after 36 h.     

γ-Linolenic acid from caryophyllaceae seed oil

Seeds from 50 species belonging to the family Caryophyllaceae, subfamilies Alsinoideae, Silenoideae, and Spergulaceae, were surveyed in a search for new sources of γ-linolenic acid (GLA) having low levels of other interfering PUFA and therefore appropriate for GLA purification. It was detected mainly in Alsinoideae species, with a maximum of 15.6% of total FA in Minuartia laricifolia subsp. ophiolitica. Different amounts of stearidonic acid (18∶4n−3) were present in the Alsinoideae species, ranging from undetectable levels in seven species to 3.30% of total FA in Stellaria media. An ANOVA showed a taxonomical correlation between GLA percentages and the genus/subfamily within this family.     

Inhibitory Effect of Conjugated α-Linolenic Acid from Bifidobacteria of Intestinal Origin on SW480 Cancer Cells

In this study, we assessed the ability of six strains of bifidobacteria (previously shown by us to possess the ability to convert linoleic acid to c9, t11-conjugated linoleic acid (CLA) to grow in the presence of α-linolenic acid and to generate conjugated isomers of the fatty acid substrate during fermentation for 42 h. The six strains of bifidobacteria were grown in modified MRS (mMRS) containing α-linolenic acid for 42 h at 37 °C, after which the fatty acid composition of the growth medium was assessed by gas liquid chromatography (GLC). Indeed, following fermentation of one of the strains, namely Bifidobacterium breve NCIMB 702258, in the presence of 0.41 mg/ml α-linolenic acid, 79.1% was converted to the conjugated isomer, C18:3 c9, t11, c15 conjugated α-linolenic acid (CALA). To examine the inhibitory effect of the fermented oils produced, SW480 colon cancer cells were cultured in the presence of the extracted fermented oil (10–50 μg/ml) for 5 days. The data indicate an inhibitory effect on cell growth (p ≤ 0.001) of CALA, with cell numbers reduced by 85% at a concentration of 180 μM, compared with a reduction of only 50% with α-linolenic acid (p ≤ 0.01).     

Flaxseed Treatments to Reduce Biohydrogenation of α-Linolenic Acid by Rumen Microbes in Cattle

Enrichment of beef muscle with n-3 fatty acids (FA) is one means to introduce these FA into the diet, but ruminal biohydrogenation limits their bioavailability. To address this problem, we evaluated the ability of condensed tannin (quebracho), in the presence or absence of casein, to protect 18:3n-3 in flaxseed from hydrogenation by ruminal microbes in cattle using an in vitro fermentation approach coupled with evaluation in cattle in vivo. Treated and untreated flaxseed was incubated with bovine rumen fluid for 0 and 24 h. With tannin treated flaxseed, hydrogenation of 18:3n-3 was limited to only 13% over 24 h compared to 43% for untreated flaxseed, while addition of casein to the tannin added no additional protection. To determine if a similar level of protection would occur in vivo, we used two groups of five steers fed either a grain-based or forage-based diet. Five steers were given a grain-based diet during the trial and were fed either ground flaxseed or tannin treated flaxseed for 15 days prior to blood collection for plasma lipid fatty acid analysis. The forage fed steers followed the same regimen. Ingestion of tannin-treated flaxseed did not increase 18:3n-3 and 20:5n-3 in plasma neutral lipids as compared to non-treated flaxseed. Thus, we demonstrated that treating ground flaxseed with quebracho tannin is not useful for increasing 18:3n-3 in the neutral lipid of bovine blood plasma, and suggest caution when interpreting results from in vitro trials that test potential treatments for protecting fatty acids from hydrogenation by ruminal microbes.     

Repletion of n-3 Fatty Acid Deficient Dams with α-Linolenic Acid: Effects on Fetal Brain and Liver Fatty Acid Composition

Docosahexaenoic acid (DHA) supply to the fetal brain depends upon the dam’s dietary intake of n-3 fats. In this study, we measured the incorporation of DHA into the fetal brain and liver in n-3 fatty acid deficient (0.1% alpha-linolenate) mice upon switching to an n-3 fatty acid adequate (2.1% alpha-linolenate) diet. Second generation mice raised and maintained on an n-3 deficient diet during mating were switched to an n-3 adequate diet on embryonic day 1 (ED 1) or ED 13. Fatty acid analysis was performed on fetal brains and livers and on maternal serum on ED 13, 15, 17, and 19. Although fetal brain and liver DHA began at a very low level (both exhibited an 85% decline), recovery was nearly complete by ED 15 in the group switched near conception but thereafter diverged. The maternal serum and fetal liver were very similar in their DHA and docosapentaenoic acid time courses. However, when repletion began on ED 13, brain DHA recovery was only about 44%. These results suggest that a nutritional intervention with alpha-linolenic acid can nearly but incompletely rescue the mouse fetal DHA deficiency if began at the time of conception but that the third trimester is too late, thus leaving a large DHA gap.     

Mass Spectrometric Confirmation of γ-Linolenic Acid Ester-Linked Ceramide 1 in the Epidermis of Borage Oil Fed Guinea Pigs

Ceramide 1 (Cer1), a Cer species with eicosasphingenine (d20:1) amide‐linked to two different ω‐hydroxy fatty acids (C30wh:0:C32wh:1), which are, in turn, ester‐linked to linoleic acid (LNA; 18:2n‐6), plays a critical role in maintaining the structural integrity of the epidermal barrier. Prompted by the recovery of a disrupted epidermal barrier with dietary borage oil [BO: 36.5 % LNA and 23.5 % γ‐linolenic acid (GLA; 18:3n‐6)], in essential fatty acid (EFA)‐deficient guinea pigs, we further investigated the effects of BO on the substitution of ester‐linked GLA for LNA in these two epidermal Cer1 species by LC–MS in positive and negative modes. Dietary supplementation of BO for 2 weeks in EFA‐deficient guinea pigs increased LNA ester‐linked to C32wh:1/d20:1 and C30wh:0/d20:1 of Cer1. Moreover, GLA ester‐linked to C32wh:1/d20:1, but not to C30wh:0/d20:1, of Cer1 was detected, which was further confirmed by the product ions of m/z 277.2 for ester‐linked GLA and m/z 802.3 for the deprotonated C32wh:1/d20:1. C20‐Metabolized fatty acids of LNA or GLA were not ester‐linked to these Cer1 species. Dietary BO induced GLA ester‐linked to C32wh:1/d20:1 of epidermal Cer1.     

Investigation of γ-Linolenic Acid and Stearidonic Acid Biosynthesis During a Life Cycle of <Emphasis Type="Italic">Borago officinalis</Emphasis> L.

This study investigated the levels of γ-linolenic (GLA, 18:3n-6) and stearidonic acid (SDA, 18:4n-3) in various parts of the borage plant (Borago officinalis L.) to elucidate Δ6-desaturase activity. Lipid class and fatty acid (FA) composition during germination of the seeds and FA composition of various borage parts were determined as well as FA compositions of neutral lipids (NL), polar lipids (PL), glycolipids (GL) and monogalactosyl diacylglycerols (MGDG) of borage leaves. When seeds were germinated for 12 days in the dark then exposed to light for 8 h, an overall decrease in oil content was seen with a significant increase in PL from 0.2 to 39.1%. An increase in SDA (from 0.2 to 0.6 g/100 g oil) indicated minor FA synthesis during germination and therefore, Δ6-desaturase activity with the most marked increase after light exposure. The FA compositions of developing and mature seeds were similar, suggesting oil/FA synthesis takes place at the initial stage of seed development. Among all the borage parts, the leaves had the highest amounts of α-linolenic acid (ALA, 18:3n-3) (36.2%), indicating Δ15-desaturase activity, and SDA (25.2%), indicating Δ6-desaturase activity. In leaves, the GL and especially, MGDG fractions had the highest amounts of SDA (31.8 and 39.8%, respectively), indicating that Δ6-desaturase is most active in chloroplasts. Leaves and developing seeds appear to be the major sources of Δ6-desaturase in borage, associated with different organelles in the different tissues.     

Serum n-3 Tetracosapentaenoic Acid and Tetracosahexaenoic Acid Increase Following Higher Dietary α-Linolenic Acid but not Docosahexaenoic Acid

n‐3 Tetracosapentaenoic acid (24:5n‐3, TPAn‐3) and tetracosahexaenoic acid (24:6n‐3, THA) are believed to be important intermediates to docosahexaenoic acid (DHA, 22:6n‐3) synthesis. The purpose of this study is to report for the first time serum concentrations of TPAn‐3 and THA and their response to changing dietary α‐linolenic acid (18:3n‐3, ALA) and DHA. The responses will then be used in an attempt to predict the location of these fatty acids in relation to DHA in the biosynthetic pathway. Male Long Evans rats (n = 6 per group) were fed either a low (0.1% of total fatty acids), medium (3%) or high (10%) ALA diet with no added DHA, or a low (0%), medium (0.2%) or high (2%) DHA diet with a background of 2% ALA for 8 weeks post‐weaning. Serum n‐3 and n‐6 polyunsaturated fatty acid (PUFA) concentrations (nmol/mL ± SEM) were determined by gas chromatography–mass spectrometry. Serum THA increases from low (0.3 ± 0.1) to medium (5.8 ± 0.7) but not from medium to high (4.6 ± 0.9) dietary ALA, while serum TPAn‐3 increases with increasing dietary ALA from 0.09 ± 0.04 to 0.70 ± 0.09 to 1.23 ± 0.14 nmol/mL. Following DHA feeding, neither TPAn‐3 or THA change across all dietary DHA intake levels. Serum TPAn‐3 demonstrates a similar response to dietary DHA. In conclusion, this is the first study to demonstrate that increases in dietary ALA but not DHA increase serum TPAn‐3 and THA in rats, suggesting that both fatty acids are precursors to DHA in the biosynthetic pathway.     

Synthesis and Characterization of the Inclusion Complex of β-cyclodextrin and Azomethine

A β-cyclodextrin (β-Cyd) inclusion complex containing azomethine as a guest was prepared by kneading method with aliquot addition of ethanol. The product was characterized by Fourier Transform Infrared (FTIR) spectrometer, ¹H Nuclear Magnetic Resonance (¹H NMR) and Thermogravimetric Analyzer (TGA), which proves the formation of the inclusion complex where the benzyl part of azomethine has been encapsulated by the hydrophobic cavity of β-Cyd. The interaction of β-Cyd and azomethine was also analyzed by means of spectrometry by UV-Vis spectrophotometer to determine the formation constant. The formation constant was calculated by using a modified Benesi-Hildebrand equation at 25 °C. The apparent formation constant obtained was 1.29 × 10⁴ L/mol. Besides that, the stoichiometry ratio was also determined to be 1:1 for the inclusion complex of β-Cyd with azomethine.     

Production and investigation of structure and properties of polyethylene–polylactide composites

Under conditions of shear deformations, low-density polyethylene (LDPE) and polylactide (PLA) composites are obtained in rotor disperser. The production of these composites allows one to use polymers derived from natural raw and to reduce the cost of the materials on their base. The addition of rigid PLA leads to increase in elastic modulus from 200 for LDPE to 1190 for LDPE–PLA (50:50 wt %) composites and in tensile strength from 13.3 for LDPE to 17.8 for LDPE–PLA. By differential scanning calorimetry method, it is shown that LDPE and PLA are incompatible. Using X-ray diffraction analysis, it is found that degree of crystallinity of composites decreases from 46.1 at 50:50 wt % to 36.9 at 80:20 wt % component ratios with the rise in LDPE content. Tests on fungus resistance show that the composites containing 50 wt % PLA are more resistant than the composites containing 30 wt % PLA. First by gel-permeation chromatography method, it is shown that composite degradation after exposure in soil is accompanied by the PLA chain scission and depolymerization with formation of monomers and dimers (M _w of PLA decreases from 118,860 to 80,100). The obtained composites can be applied as packaging materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47598.     

Investigation of Structure and Oxidation Behavior of Pitch and Resin Resultant Carbon

The structure and oxidation behaviors of pitch carbon,resin carbon and their mixture re-sultant carbon have been investigated.The results indicate that the pitch carbon has relative higher true specific gravity,well developed crystalline and better oxidation resistance than resin carbon,With 20%-35% resin added to pitch,the structure of the resultant carbon can be modified and oxidation resistance will be improved significantly.