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.     

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.     

Evaluation of Physicochemical and Antifungal Properties of Polylactic Acid–Thermoplastic Starch–Chitosan Biocomposites

Biocomposites of polylactic acid, thermoplastic starch, chitosan powder, and chitosan lyophilized powder were prepared using an extrusion process. The color, thermal, structural, mechanical, morphology, and antimicrobial properties were evaluated. The addition of thermoplastic starch and chitosan (chitosan powder and chitosan lyophilized powder) produced significant changes in color and heterogeneous surface morphology of the polylactic acid biocomposites. The thermal, mechanical, and morphometric properties of the material showed changes with the addition of thermoplastic starch and chitosan (chitosan powder and chitosan lyophilized powder). The biocomposites formulated with chitosan powder and chitosan lyophilized powder showed antifungal activity when evaluating this property. The biocomposites produced could be used in packaging applications.     

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.     

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.     

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.     

Decreasing the Linoleic Acid to α-Linolenic Acid Diet Ratio Increases Eicosapentaenoic Acid in Erythrocytes in Adults

The n-6/n-3 fatty acid (FA) ratio has increased in the Western-style diet to ~10–15:1 during the last century, which may have contributed to the rise in cardiovascular disease (CVD). Prior studies have evaluated the effects on CVD risk factors of manipulating the levels of n-6 and n-3 FA using food and supplements or investigated the metabolic fate of linoleic acid (LNA) and α-linolenic acid (ALA) by varying the n-6/n-3 ratios. However, no previous studies have investigated the potential interaction between diet ratios and supplementation with eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3). We used a factorial design approach with adults (n = 24) in a controlled feeding trial to compare the accretion of EPA and DHA into red blood cell membranes (RBC) by adding a direct source (algal oil supplement) of EPA and DHA in a diet with a 10:1 versus 2:1 ratio of n-6/n-3 FA. Subjects were randomized into 8-week crossover diet sequences and each subject consumed three of four diets [10:1, 10:1 plus supplement (10:1 + S), 2:1 and 2:1 + S]. LNA and ALA intakes were 9.4 and 7.7%, and 1.0 and 3.0% during the low and high ALA diets, respectively. Compared to the Western-style 10:1 diet, the 2:1 diet increased EPA by 60% (P < 0.0001) in RBC membranes without the direct EPA source and a 34% increase (P = 0.027) was observed with the 10:1 + S diet; however, DHA levels increased in both diet ratios only with a direct DHA source. Shifting towards a 2:1 diet is a valid alternative to taking EPA-containing supplements.     

Synthesis and Aqueous Solution Properties of α-Dimethyl Oxamino Dodecyl Acid

Starting from α-chloro-lauric acid which was obtained from lauric acid through selectively chlorinating at the α-position with chlorine, a novel surfactant α-dimethyl oxamino dodecyl acid was synthesized with high yield via an economic route. The structure of α-dimethyl oxamino dodecyl acid was confirmed by means of Fourier transform infrared spectroscopy, electrospray ionization mass spectrometry and ¹H nuclear magnetic resonance spectroscopy. Surface tension, foaming properties and emulsifying measurements were performed to study the aqueous solution properties of the synthesized surfactant. The results showed that the behavior of the α-dimethyl oxamino dodecyl acid strongly depend on the pH of aqueous solution: it had high surface activity, excellent foaming properties and emulsion stability for paraffin oil at acid pH while the corresponding properties decrease substantially at alkaline pH.     

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.     

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).     

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.     

Effect of Saturated/Unsaturated Fatty Acid Ratio on Physicochemical Properties of Palm Olein–Olive Oil Blend

Although blending polyunsaturated oil with more saturated or monounsaturated oils has been studied extensively, there is no similar information regarding the partial replacement of palm olein with olive oil (OO). Therefore the main objective of this study was to investigate the effects of OO partial replacement (0, 25, 50, 75, 90 and 100% w/w) on the chemical stability of palm olein oil (POO). The physicochemical properties of oil samples namely iodine value, peroxide value (PV), anisidine value, TOTOX value (total oxidation value, TV), free fatty acid (FFA), cloud point, color and viscosity were considered as response variables. Significant differences among the oil blend properties were determined at the significance level of P < 0.05. Apart from FFA, all the response variables were significantly influenced by type and concentration of oils. The oil blend containing 10% POO and 90% OO showed the highest TV (6.10); whereas the blend containing 90% POO and 10% OO exhibited the least TV (2.41). This study indicated that the chemical stability of oil blend significantly (P < 0.05) increased with increasing the proportion of polyunsaturated/monounsaturated fatty acid.     

β-Cyclodextrin Inclusion Complex to Improve Physicochemical Properties of Pipemidic Acid: Characterization and Bioactivity Evaluation

The aptitude of cyclodextrins (CDs) to form host-guest complexes has prompted an increase in the development of new drug formulations. In this study, the inclusion complexes of pipemidic acid (HPPA), a therapeutic agent for urinary tract infections, with native β-CD were prepared in solid state by kneading method and confirmed by FT-IR and ¹H NMR. The inclusion complex formation was also characterized in aqueous solution at different pH via UV-Vis titration and phase solubility studies obtaining the stability constant. The 1:1 stoichiometry was established by a Job plot and the inclusion mechanism was clarified using docking experiments. Finally, the antibacterial activity of HPPA and its inclusion complex was tested on P. aeruginosa, E. coli and S. aureus to determine the respective EC_50s and EC_90s. The results showed that the antibacterial activity of HPPA:β-CD against E. coli and S. aureus is higher than that of HPPA. Furthermore, HPPA and HPPA:β-CD, tested on human hepatoblastoma HepG2 and MCF-7 cell lines by MTT assay, exhibited, for the first time, antitumor activities, and the complex revealed a higher activity than that of HPPA. The use of β-CD allows an increase in the aqueous solubility of the drug, its bioavailability and then its bioactivity.     

The Production of Conjugated α-Linolenic, γ-Linolenic and Stearidonic Acids by Strains of Bifidobacteria and Propionibacteria

Conjugated fatty acids are regularly found in nature and have a history of biogenic activity in animals and humans. A number of these conjugated fatty acids are microbially produced and have been associated with potent anti-carcinogenic, anti-adipogenic, anti-atherosclerotic and anti-diabetogenic activities. Therefore, the identification of novel conjugated fatty acids is highly desirable. In this study, strains of bifidobacteria and propionibacteria previously shown by us and others to display linoleic acid isomerase activity were assessed for their ability to conjugate a range of other unsaturated fatty acids during fermentation. Only four, linoleic, α-linolenic, γ-linolenic and stearidonic acids, were converted to their respective conjugated isomers, conjugated linoleic acid (CLA), conjugated α-linolenic acid (CLNA), conjugated γ-linolenic acid (CGLA) and conjugated stearidonic acid (CSA), each of which contained a conjugated double bond at the 9,11 position. Of the strains assayed, Bifidobacterium breve DPC6330 proved the most effective conjugated fatty acid producer, bio-converting 70% of the linoleic acid to CLA, 90% of the α-linolenic acid to CLNA, 17% of the γ-linolenic acid to CGLA, and 28% of the stearidonic acid to CSA at a substrate concentration of 0.3 mg mL⁻¹. In conclusion, strains of bifidobacteria and propionibacteria can bio-convert linoleic, α-linolenic, γ-linolenic and stearidonic acids to their conjugated isomers via the activity of the enzyme linoleic acid isomerase. These conjugated fatty acids may offer the combined health promoting properties of conjugated fatty acids such as CLA and CLNA, along with those of the unsaturated fatty acids from which they are formed.     

Designs of Bioreactor Systems for Solvent-Free Lipase-Catalyzed Synthesis of Fructose–Oleic Acid Esters

Fructose–oleic acid esters, biodegradable, biocompatible and biobased surfactants and value-added products were synthesized under solvent-free conditions at 65 °C in stirred-batch mode and using several different bioreactor systems. For a stirred-tank bioreactor (STBR) using fed-batch fructose addition and 5.0 wt.% immobilized Rhizomucor miehei lipase (Lipozyme^® IM, Novozymes, Franklinton, NC), the conversion yield was over 80%, and the initial rate of the reaction was comparable to previously obtained results using tert-butanol during the initial phase. The bioreactor systems contained a packed “desorption” column (DC) containing fructose crystals and silica gel for delivery of saccharide, and either a STBR or packed-bed bioreactor (PBBR). The liquid stream, initially containing oleic acid and a mixture of fructose–oleic acid esters at a ratio of 75/25 w/w, was continuously recirculated throughout the system. The PBBR system yielded the highest conversion (84.4%) and rate of reaction subsequent to the addition of 10 wt.% molecular sieves during the latter stage of reaction; however, the reaction rate was several-fold lower than the batch mode reactions due to the lower fructose concentrations provided by the DC.     

Chemical Properties of 2‐Bromodecanoic Acid

Abstract

Some chemical equilibrium constants for 2‐bromodecanoic acid were investigated. The dimerization constant of 2‐bromodecanoic acid, k₂ =278 M^?1, in tert‐butylbenzene was first derived from IR spectroscopy measurements. Secondly, the distribution coefficient, k _d =799, was found by combining the value of k₂ with distribution data obtained from solvent extraction experiments evaluated with the aid of neutron activation analysis. Finally the dissociation constant, k _a =3.18 ?10^?3 M, was estimated from two‐phase titrations. A theoretical calculation was made based on the obtained constants and this calculation was validated by a second solvent extraction experiment that gave a good correspondence between calculated and experimental values.     

Preparation and Properties of α-Cellulose Short Fiber-Reinforced Poly(lactic Acid) Composites

The objective of this study is to fabricate the PLA/α-cellulose composites and to investigate the effect of α-cellulose short fibers on the toughness improvement of PLA. To homogeneously disperse the polar α-cellulose in the non-polar PLA matrix, the as-received α-cellulose was subjected to surface modification using stearic acid to impart the hydrophobic characteristics to the short fibers. The α-cellulose fibers dispersed more homogeneously in PLA through this modification, and consequently, the fiber pull-out and longer micro-crack length could improve the toughness and damping property of the resulting PLA composites. The inclusion of α-cellulose short fibers considerably decreased the spherulite dimension of the PLA/α-cellulose composites to accommodate larger deformation through grain boundary sliding. The PLA/α-cellulose composite improved its toughness by three times that of the neat PLA with low α-cellulose content (～4 wt.%), and maintained its transparency.     

Physicochemical Properties and Metallurgical Evaluation of Magnesium—Strontium-Containing Limestones

Theoretical Foundations of Chemical Engineering - Magnesium—strontium-containing limestones are overburden and lie together with celestite ore, the extraction of which is economically...     

Combustion and Heat Properties of Lignin–Containing Fuels

Results of studying the combustion process of pellet fuels produced on the basis of obsolete gun powder and lignin are described. The temperatures of diffusion combustion of the flame and coke of pellet fuels and the linear velocities of flame and flame–free stages of combustion are determined. A model is proposed, and calculation results for the radiant component in the overall balance of combustion heat of lignin–containing fuels are presented.