Fatty Acid Chain Length Research Articles

The effects of fatty acids chain length on the techno-functional properties of basil seed gum-based edible films

In this study, the effects of various fatty (including caprylic, lauric, and palmitic) acids on physicochemical, mechanical, and barrier properties of basil seed gum (BSG)-based edible films were investigated. The introduction of fatty acids (FAs) into the BSG-based matrix was confirmed by FT-IR. Increasing the FA chain length resulted in an increase in the thickness and opacity of FA-modified BSG films, while water solubility decreased. The water vapor permeability (WVP) of FA-modified films was significantly (P < 0.05) lower than that of control film. The mechanical properties and color attributes of edible films were improved after incorporating caprylic and lauric acids. SEM micrographs revealed a more homogenous microstructure with a higher surface density in the films incorporated with caprylic acid, while a higher roughness and insoluble particles were observed in those incorporated with lauric, and palmitic acids. Our findings showed that lauric acid is a good candidate for improving the barrier and textural characteristics of BSG-based edible films.

Modified electrospun chitosan membranes for controlled release of simvastatin.

Chitosan nanofibrous membranes have immense potential in tissue engineering and drug delivery applications because of their increased surface area, high degree of biocompatibility, and their ability to mimic the extracellular matrix. However, their use is often limited due to their extreme hydrophilic nature causing them to lose their nanofibrous structure in vivo. In the present study, chitosan membranes were modified either by acylation reactions using fatty acids of different chain lengths or tert-butyloxycarbonyl (tBOC) protecting groups to increase the hydrophobicity of the membranes and protect the nanofibrous structure. The modified membranes were characterized using scanning electron microscopy, attenuated total reflectance Fourier transform infrared spectroscopy, water contact angle and elemental analysis to confirm the addition of the modification groups. These membranes were then evaluated to control the release of a hydrophobic osteogenic drug-simvastatin (SMV). The interaction between SMV and the polymer was determined using molecular modeling. Pure SMV and SMV loaded membranes were examined for their in vitro cytotoxicity and osteogenic potential using preosteoblast mouse bone marrow stromal cells. From results, it was evident that as the fatty acid chain length increased from two to six methylene groups, the hydrophobicity of the membranes increased (59.2±8.2° to 94.3±8.5° water contact angle). The amount of drug released from the membranes could be controlled by changing the amount of initial drug loaded and/or the type of modifications. After 4 weeks, for a 500μg loading, the short chain fatty acid modified membranes released 17.8±3.2% of the drug whereas a long chain fatty acid released only 4.8±0.8%. Similarly, for a 50μg loading, short chain modified membranes released more (73.3±33.3%) of the loaded drug as compared to the long chain membranes (43.0±3.5%). The long chain fatty acid membranes released SMV for extended time periods of up to 90days. This data was further supported by molecular modeling, which revealed that SMV was more compatible with more hydrophobic membranes. Cell studies showed that pure SMV from 75 to 600ng/ml range possessed osteogenic potential in a dose dependent manner and the amount of SMV released from the most hydrophobic FA treated membranes was not cytotoxic and supported osteogenic differentiation. Therefore, this study demonstrates our ability to control the release of a hydrophobic drug from modified chitosan membranes as per the clinical need.

Fatty acid chain length impacts nanonizing capacity of albumin-fatty acid nanomicelles: Enhanced physicochemical property and cellular delivery of poorly water-soluble drug

This study aimed to design the ideal nanonizing vehicle for poorly water-soluble model curcumin (CCM) using fattigation-platform nanotechnology, and to investigate the effects of fatty acid salts chain length on nanonizing CCM and its efficient delivery to different cancer cells. HSA-fatty acid conjugates were synthesized by EDC/NHS coupling. Fattigation-platform nanomicelles (NMs), prepared by film hydration, exhibited uniform and spherical morphology, although, each NM varied in particle size, zeta potential, and critical micelle concentration according to the types of fatty acid. Preliminary solubility studies of albumin conjugates with 5 types of fatty acid salts of different chain lengths revealed that C14 exhibited the highest solubilization of CCM. CCM-loaded HSA-C14 NMs demonstrated the highest drug content (5.35 ± 0.48%) and loading efficiency (95.93 ± 1.87%) compared to other NMs. It exhibited enhanced drug release rate and reduced micelle size in biorelevant dissolution medium. Interestingly, this solubilization approach was well applied in poorly water-soluble docetaxel trihydrate (DTX). Preliminary solubility results of DTX was also corresponded to the stable nanonization phenomenon in biorelevant dissolution medium. Compared to the CCM EtOH solution, HSA-C14 NMs showed higher internalization in cancer cell lines A549 and MCF-7, and consequently, exhibited significantly increased cytotoxicity against both cell lines. Therefore, this study provides a new solubilization approach for poorly water-soluble drugs using fatty acid salts of different chain lengths and their micellar formations via nanonization, which could be a promising tool for targeted cancer therapy using poorly water-soluble drugs.

A mechanistic study of emulsion flooding for mobility control in the presence of fatty acids: Effect of chain length

Emulsion flooding is a promising method for enhanced oil recovery (EOR). The static and dynamic behavior of the emulsions is greatly influenced by the nature of the applied surfactant. In this work, the effect of fatty acids, as natural surface-active agents, and their chain length on the emulsion behavior was investigated in both bulk and porous media. A panel of the fatty acids with different chain lengths (6 < C < 18) was applied at constant concentration and pH. Upon the static stability tests, emulsion stability at the optimum value of chain length (C14) was increased by two orders of magnitude. Under the optimal condition, the hydrogen bonding between dissociated and undissociated fatty acids and the tail-to-tail adsorption of fatty acids enhanced the interface coverage. Moreover, interfacial tension was minimum in this case (35.8 mN/m). Additionally, a series of rheological measurements were conducted to examine the dynamic behavior of the emulsion. Two distinct regions were distinguished based on the shear rate. At the low shear rates, a linear relationship was observed between shear rate and shear stress, indicating a solid-like behavior of the emulsions. The effect of the fatty acid chain length on the hydrodynamic interactions was more evident at higher shear rates. Finally, the flooding experiments revealed that there is an excellent consistency between static and dynamic tests. Based on these results, a four-fold increment was recorded in the apparent viscosity of the emulsion in the optimum condition.

One-pot biocatalytic synthesis and antioxidant activities of highly lipophilic naringin derivatives by using bi-functional whole-cells

Citrus peel wastes are an important renewable resource and rich in naringin, a flavonoid compound with multiple bioactivities. To cope with the low bioavailability of naringin, a new bienzyme whole-cell system was developed for bioconversion of naringin into two lipophilic derivatives. A series of naringin esters with different fatty acid chain length were successfully synthesized via cell-bound lipase catalyzed acylation, and another lipophilic product naringenin was simultaneously yielded via intracellular naringinase-catalyzed hydrolysis. The naringin esters obtained showed higher log P values and free radical-scavenging capacities against DPPH and ABTS than naringin itself. These esters also showed markedly enhanced permeability across the human intestinal Caco-2 cells. The whole-cell mediated conversion of naringin offers a two-fold advantage: naringin esters are produced as new high-valued derivatives with high lipophilicity and antioxidant activity; and the tasteless product naringenin was obtained simultaneously, which can reduce the bitterness of the total product and benefited its industrial applications.

Importance of the fatty acid chain length on in vitro and in vivo anticancer activity of fattigation-platform albumin nanoparticles in human colorectal cancer xenograft mice model

The aims of this study were to design different chain length fatty acid-conjugated albumin nanoparticles (ANPs) and evaluate their anticancer activity in the HCT116 human colorectal cancer xenograft mouse model. Doxorubicin hydrochloride (DOX·HCl) was chosen as a model drug. The different chain lengths of fatty acids (butyric acid; C4, and stearic acid; C18) in albumin conjugates exhibited different physicochemical properties and anticancer activity. Fatty acid-conjugated albumin aided the formation of self-assembled structures with an average size of approximately 200 nm and a negative charge when incubated with excess DOX in an aqueous solution. DOX-loaded long-chain C18-conjugated ANPs allowed efficient encapsulation of hydrophobic DOX into the core of the self-assembled structure, enabling higher drug loading, enhanced colloidal stability and controlled release behavior in PBS pH 7.4 medium as compared with free DOX·HCl or non-fatty acid conjugated ANPs. Furthermore, DOX-loaded fatty acid-conjugated ANPs showed an increased cellular uptake intensity and cytotoxic effects in vitro. In vivo, HCT116 xenograft model experiments confirmed that DOX-loaded C18-conjugated ANPs showed improved anticancer activity and reduced side effects compared with the DOX-treated groups. The long-chain fatty acid-conjugated ANPs synergistically activated the interaction with the free-fatty acid receptor (FFAR) on HCT116 colorectal cancer cells as compared with short-chain C4 or other non-conjugated ANPs. Specifically, DOX-loaded C18-conjugated NPs exhibited significant performance to overexpressed FFAR4 on HCT116 colorectal cancer cells. The fatty acid chain length in the fattigation-platform system could be a promising molecular moiety to improve targeting efficiency and drug accumulation in various cancer therapy.

Improved Production of Two Anti-Candida Lipopeptide Homologues Co- Produced by the Wild-Type Bacillus subtilis RLID 12.1 under Optimized Conditions.

Antifungal cyclic lipopeptides, bioactive metabolites produced by many species of the genus Bacillus, are promising alternatives to synthetic fungicides and antibiotics for the biocontrol of human pathogenic fungi. In a previous study, the co- production of five antifungal lipopeptides homologues (designated as AF1, AF2, AF3, AF4 and AF5) by the producer strain Bacillus subtilis RLID 12.1 using unoptimized medium was reported; though the two homologues AF3 and AF5 differed by 14 Da and in fatty acid chain length were found effective in antifungal action, the production/ yield rate of these two lipopeptides determined by High-Performance Liquid Chromatography was less in the unoptimized media. In this study, the production/yield enhancement of the two compounds AF3 and AF5 was specifically targeted. Following the statistical optimization (Plackett-Burman and Box-Behnken designs) of media formulation, temperature and growth conditions, the production of AF3 and AF5 was improved by about 25.8- and 7.4-folds, respectively under static conditions. To boost the production of these two homologous lipopeptides in the optimized media, heat-inactivated Candida albicans cells were used as a supplement resulting in 34- and 14-fold increase of AF3 and AF5, respectively. Four clinical Candida auris isolates had AF3 and AF5 MICs (100 % inhibition) ranging between 4 and 16 μg/ml indicating the lipopeptide's clinical potential. To determine the in vitro pharmacodynamic potential of AF3 and AF5, time-kill assays were conducted which showed that AF3 (at 4X and 8X concentrations) at 48h exhibited mean log reductions of 2.31 and 3.14 CFU/ml of C. albicans SC 5314, respectively whereas AF5 at 8X concentration showed a mean log reduction of 2.14 CFU/ml. With the increasing threat of multidrug-resistant yeasts and fungi, these antifungal lipopeptides produced by optimized method promise to aid in the development of novel antifungal that targets disease-causing fungi with improved efficacy.

Complementary approach for analysis of phospholipids by liquid chromatography hyphenated to elemental and molecular mass spectrometry.

Phospholipids are one of the most important lipid categories with multiple functions in biological systems. Their analysis can contribute to a better understanding of metabolomic and kinetic processes in living cells. Comprehensive methods based on liquid chromatography coupled to mass spectrometry are available for phospholipid identification and quantification. However, quantification of phospholipids using electrospray ionization-mass spectrometry with internal standards is still challenging due to several reasons. In particular, the detector response of phospholipid species differs with variation of the head group as well as the fatty acid chain length and double bond number. Inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS) provides an alternative approach for their absolute quantification with universal detector response for phosphorus independent of its chemical form and proportional to its quantity. Therefore, a quantification method based on compound-independent calibration using hydrophilic interaction liquid chromatography (HILIC) coupled to ICP-MS/MS was developed. An inverse gradient system was implemented for constant mobile phase composition after HILIC separation, which provides steady plasma ionization conditions. Isobaric phosphorus interferences were decreased by using the oxygen reaction mode of the triple quadrupole based ICP-MS/MS instrument. Complementary molecular information was obtained by ESI-high-resolution MS and MS/MS. The applicability of this approach was demonstrated in a proof of concept by complementary analysis of a total lipid extract of baker's yeast.

Skin surface lipidomics revealed the correlation between lipidomic profile and grade in adolescent acne.

Acne is a multifactorial skin disorder frequently observed during adolescence with different grades of severity. The crucial factors of acne are the increase of lipids secretion and the change of composition on the skin surface lipid (SSL). However, there are no studies on the changes of lipid composition and content between different grades of adolescent acne in lesional skin and nonlesionsal skin. This study was to investigate correlation in the composition of SSL and different grades in order to understand the tendency of SSL alterations in this disease for successful acne management and prevention. A powerful analytical technique, UPLC-QTOF-MS, and multivariate data analysis were used to investigate SSL variations of lipid main classes, subclasses, and species. The results indicated that sphinganine, triradylglycerols (TG), and phytosphingosine were important in adolescent acne development. The average fatty acids (FAs) chain length in patients with acne showed significantly shortened trend from mild to moderate adolescent acne. Additionally, the relative average content of TG, diglyceride (DG), FA, ceramides (Cers), and the level of unsaturated FAs significantly increased from mild to moderate adolescent acne. Interestingly, our results demonstrated that the phytosphingosine and sphinganine showed an increasing trend in mild acne groups, but decreasing trend in lesional skin of moderate group. Lipidomics analysis suggested that the variation of TG, phytosphingosine, and sphinganine was closely related to the occurrence severity of acne in adolescent.

Unique Aspects of Lipid Metabolism in the Human Gut Microbiome

Fatty acids are abundant nutrients in the gut, and this work identified the biochemical pathway for fatty acid utilization in the prominent anaerobic, Gram‐negative inhabitants of the gut microbiome, the phylum Bacteroidetes. Alistipes finegoldii is a representative Bacteroidetes resident of the human gut. This organism has not been well studied until recently developed culture conditions enabled growth of the organism in the laboratory setting. This study identifies two unique aspects of lipid metabolism in A. finegoldii.The glycerolipid phosphatidylethanolamine (PE) synthesis is initiated by the PlsX/PlsY/PlsC pathway, whereas the sphingolipid sulfonolipid (SL) pathway is predicted to be related to sphingolipid biosynthesis. Neither phosphatidylglycerol nor cardiolipin were present. A. finegoldii incorporates medium‐chain fatty acids (£ 14 carbons) into PE or the SL after their elongation, whereas long‐chain fatty acids (³ 16 carbons) are not elongated. Acyl‐ACP &gt;16 carbons were only incorporated into the 2‐position due to the selectivity of PlsC, the only biosynthetic enzyme that efficiently utilizes long‐chain unsaturated acyl‐ACP. This ability to assimilate a broad‐spectrum of fatty acid chain lengths is due to the expression of two acyl‐acyl carrier protein (ACP) synthetases. Biochemical characterization of these enzymes showed that acyl‐ACP synthetase 1 had a substrate preference for medium‐chain fatty acids and synthetase 2 had a substrate preference for long‐chain fatty acids. This unique combination of synthetases allows A. finegoldii to efficiently utilize both medium‐and long‐chain fatty acid nutrients available in the gut environment to assemble its membrane lipids.Bioinformatics analysis of A. finegoldii suggests the genes involved in the central fatty acid elongation cycle are present. Enoyl‐acyl carrier protein reductase (FabI) catalyzes a FASII rate‐controlling step. We studied A. finegoldii FabI (AfFabI) because phylogenetic analysis places enzymes from phylum Bacteroidetes in a distinct, uncharacterized 4th FabI clade. AfFabI displays typical FabI cooperative kinetics and uses NADH as a substrate, and has the prototypical α‐helix β‐sheet dimerization and antiparallel four‐helical bundle tetramerization domains that link adjoining protomers that characterize FabI enzymes.The distinct features of AfFabI are a coiled coil domain that links the carboxy termini of adjacent protomers of the homotetramer. The AfFabI•NADH crystal structure shows each coiled coil undergoes a conformational change to form part of the NADH binding site of the adjacent protomer. Residues throughout the coiled coil contact the base of the adjacent protomer’s “flipping loop” to stabilize the open substrate‐free and closed NADH‐bound conformations. Deletion of the coiled coil causes a 20‐fold NADH Km defect, showing the coiled coils are required for high affinity NADH binding. 4th clade enzymes are distinguished by a unique coiled coil domain involved in cooperative NADH binding and a unique active site that explains why FabI compounds in the clinic don’t affect the gut microbiome.Support or Funding InformationNIH grant GM34496, American Lebanese Syrian Associated CharitiesPhylogenetic analysis places enzymes from phylum Bacteroidetes in a distinct, uncharacterized 4th FabI cladeFigure 1

Deletion and Randomization of Structurally Variable Regions in B. subtilis Lipase A (BSLA) Alter Its Stability and Hydrolytic Performance Against Long Chain Fatty Acid Esters.

The continuous search for novel enzyme backbones and the engineering of already well studied enzymes for biotechnological applications has become an increasing challenge, especially by the increasing potential diversity space provided by directed enzyme evolution approaches and the demands of experimental data generated by rational design of enzymes. In this work, we propose a semi-rational mutational strategy focused on introducing diversity in structurally variable regions in enzymes. The identified sequences are subjected to a progressive deletion of two amino acids and the joining residues are subjected to saturation mutagenesis using NNK degenerate codons. This strategy offers a novel library diversity approach while simultaneously decreasing enzyme size in the variable regions. In this way, we intend to identify and reduce variable regions found in enzymes, probably resulting from neutral drift evolution, and simultaneously studying the functional effect of said regions. This strategy was applied to Bacillus. subtilis lipase A (BSLA), by selecting and deleting six variable enzyme regions (named regions 1 to 6) by the deletion of two amino acids and additionally randomizing the joining amino acid residues. After screening, no active variants were found in libraries 1% and 4%, 15% active variants were found in libraries 2% and 3%, and 25% for libraries 5 and 6 (n = 3000 per library, activity detected using tributyrin agar plates). Active variants were assessed for activity in microtiter plate assay (pNP-butyrate), thermal stability, substrate preference (pNP-butyrate, -palmitate), and compared to wildtype BSLA. From these analyses, variant P5F3 (F41L-ΔW42-ΔD43-K44P), from library 3 was identified, showing increased activity towards longer chain p-nitrophenyl fatty acid esters, when compared to BSLA. This study allowed to propose the targeted region 3 (positions 40–46) as a potential modulator for substrate specificity (fatty acid chain length) in BSLA, which can be further studied to increase its substrate spectrum and selectivity. Additionally, this variant showed a decreased thermal resistance but interestingly, higher isopropanol and Triton X-100 resistance. This deletion-randomization strategy could help to expand and explore sequence diversity, even in already well studied and characterized enzyme backbones such as BSLA. In addition, this strategy can contribute to investigate and identify important non-conserved regions in classic and novel enzymes, as well as generating novel biocatalysts with increased performance in specific processes, such as enzyme immobilization.

The effect of medium chain and long chain triglycerides incorporated in self-nano emulsifying drug delivery systems on oral absorption of cannabinoids in rats.

The aim of this research was to investigate the effect of the lipid component in self-emulsifying drug delivery systems on the oral absorption of major cannabinoids Δ9-tetrahydrocannabinol (THC) and Cannabidiol (CBD). The investigated lipids were either long chain triglycerides (LCT) or medium chain triglycerides (MCT) with different composition, fatty acid chain length, degree of saturation and their absorption pathway to the systemic circulation. Formulations were developed with the purpose of creating thermodynamically stable oil-in-water nano emulsions/suspensions with particle size of 50nm or less which carry the lipophilic drug and increase water solubility. Following a methodic screening of suitable excipients in-vitro, leading formulations based on sesame oil or MIGLYOL® 812N (Type I LCT/MCT SNEDDS) and cocoa butter or tricaprin (Type II LCT/MCT SNEDDS) were investigated in the freely moving rat model. Results in rat model demonstrated that the effect of each type of lipid on bioavailability of cannabinoids is not straightforwardly anticipated. The differences in the effect of LCT and MCT on absorption was not substantial for Type I formulations, however, more prominent for Type II formulations. This unpredictable behavior in-vivo demonstrates the importance of investigating each vehicle pre-clinically, following the in-vitro development.

Dietary Factors and Eating Behaviors Affecting Diet-Induced Thermogenesis in Obese Individuals: A Systematic Review.

Obese individuals are considered to have lower energy expenditure (EE) rates than non-obese individuals. We aimed to investigate the effects of various factors related to food intake on diet-induced thermogenesis (DIT) in the EE of obese individuals. Using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, we reviewed relevant literature from PubMed, Embase, and Medline databases from study inception till the end of July 2019. Studies on dietary factors affecting DIT in obese individuals were included. Fifteen studies were included; these studies assessed macronutrient, single-nutrient, or supplement meal compositions, as well as dietary patterns and behaviors. The effect of obesity on DIT was not constant in each study. Differences in DIT pertained to the protein ratio being higher than the fat ratio or the carbohydrate ratio being higher than the fat ratio. High intake of calcium and vitamin D as well as high-oleic peanut supplements increased DIT in obese people. In addition, ascorbic acid intake, fatty acid saturation, and the chain length of various fatty acids had no effects on DIT. In conclusion, the findings suggest that in obese individuals, DIT is associated with various factors related to meal, nutrient, and dietary habits. However, because of the complexity of the relationship between DIT and obesity, it is difficult to determine the critical element underlying this association.

Abomasally infused SFA with varying chain length differently affect milk production and composition and alter hepatic and mammary gene expression in lactating cows.

The aim of the present study was to compare the effects of post-ruminally infused fat supplements, varying in fatty acid (FA) chain length, on animal performance, metabolism and milk FA. Eleven multiparous Holstein dairy cows were used in a replicated incomplete 3 × 3 Latin square design with 7-d periods, separated by 7-d washouts. Treatments were administered as abomasal infusions of enrichments providing 280 g/d of FA: (1) palmitic acid (98·4 % 16 : 0; PA), (2) caprylic and capric acids (56·2 % 8 : 0, 43·8 % 10 : 0; medium-chain TAG (MCT)) and (3) stearic acid (99·0 % 18 : 0; SA). Relative to PA, SA decreased the efficiency of fat-corrected milk production, which was associated with a tendency for higher DM intake and lower FA absorption with SA, whereas MCT was not different from PA for these variables. Milk fat concentration and yield were increased by PA relative to SA, but only fat yield tended to be greater relative to MCT. Relative to PA, MCT increased milk fat concentration of FA < 16 C, whereas SA increased FA > 16 C. Expression of mammary stearoyl-coA desaturase 1 was lower with SA than with PA. Relative to PA, liver expression of adenosine monophosphate-activated protein kinase-1 and pyruvate kinase was increased with MCT, whereas expression of these genes tended to be increased by SA. The mechanism of increased fat secretion with PA does not seem to be related to a modulation of the expression of lipogenesis-related genes, but rather to increased substrate availability as reflected by milk FA profile.

Quantifying the Effect of Fatty Acids on the Elasticity of Model Membranes

Dietary fatty acids function in many processes that impact cardiovascular health. Specifically, polyunsaturated fatty acids (PUFAs), are expected to improve cardiovascular function through the alteration of membrane properties of diverse cell types. Global membrane properties have increasingly been shown to impact the activity of distinct mechanosensitive membrane proteins. However, the mechanism by which these properties affect mechanosensitive channel activity remains unclear. PUFAs are hypothesized to alter bilayer mechanical properties but monoacyl fatty acids have been studied sparingly in phospholipid bilayers. Moreover, the effect of monoacyl fatty acid chain length, unsaturation, and location of unsaturation on membrane mechanical properties have not yet been determined. With these questions in mind, we incorporated monoacyl PUFAs of different chain lengths and degrees of unsaturation into phospholipid bilayers. Using micropipette aspiration and fluorescence anisotropy, we measured the effect of various PUFAs on the membrane area expansion modulus and fluidity, respectively, of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) vesicle membranes. By systematically altering the identity of fatty acids, we observed that long-chain omega-3 fatty acids—but not monounsaturated fatty acids—reduce the membrane area expansion modulus and increase the fluidity of DOPC vesicle membranes. In addition, we observe that two major omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), impact the area expansion modulus and fluidity of DOPC membranes containing cholesterol domains in different ways. These results provide insight into how EPA and DHA may have distinct effects on the bilayer properties of mammalian cells, despite being chemically similar. Our results demonstrate several ways in which dietary monoacyl fatty acids impact the mechanical properties of phospholipid bilayers and present a potential route through which fatty acid uptake into cell membranes may influence the activity of membrane proteins.

Electrocatalytic methyl esterification of fatty acid using boron-doped-diamond electrodes

Methyl esterification of free fatty acids with reduced energy intensity under ambient conditions is challenging. This paper presents an environmental friendly electrochemical approach for the methyl esterification of free fatty acids to fatty acid methyl esters with a cell voltage at 1.52 V over boron-doped diamond. The effects of supporting electrolyte and alkyl chain length of free fatty acids on the performances of the electrocatalytic methyl esterification are investigated by cyclic voltammetry, gas chromatography, gas chromatography-mass spectrometer, and high-performance liquid chromatography. A reasonable mechanism of the electrocatalytic methyl esterification method has also been proposed. Moreover, using the as-developed method, free fatty acids mixture of microalgae (Schizochytrium limacinum) oil is transformed into their corresponding fatty acid methyl esters. Fatty acid methyl esters are obtained at near-quantitative liquid selectivity at 1.52 V V for 1 h with the addition of 16.7 wt.% KOH. This work not only provides an alternative low-cost strategy for methyl esterification, but also an approach to transfer intermittent renewable sourced electricity energy and biomass into valuable chemicals and fuels.

Design of nanoemulsion-based delivery systems to enhance intestinal lymphatic transport of lipophilic food bioactives: Influence of oil type

The impact of nanoemulsions containing triglycerides with different fatty acid chain lengths on the bioavailability of a highly lipophilic bioactive: 5-demethylnobiletin (5-DN) was investigated. 5-DN was encapsulated in nanoemulsions fabricated using either medium-chain triglycerides (MCT) or long-chain triglycerides (LCT). They were then subjected to in vitro digestion, and the resulting mixed micelles was applied to a Caco-2 cell model. Higher 5-DN bioaccessibility was found for the MCT-nanoemulsion (13%) than for the LCT-nanoemulsion (7%). However, only 30% 5-DN in MCT crossed the Caco-2 monolayer and 50% was metabolized, while 60% 5-DN in LCT crossed the monolayer and only 10% was metabolized. More lipid droplets and chylomicrons were also formed for the LCT nanoemulsions, indicating greater 5-DN transported through lymph. Although MCT gave a higher 5-DN bioaccessibility, the final amount of 5-DN absorbed and transported to the lymph was inferior to that of the LCT formulation.

Self-Assembly of Exendin-4-Derived Dual Peptide Agonists is Mediated by Acylation and Correlated to the Length of Conjugated Fatty Acyl Chains

Dual glucagon-like peptide-1/glucagon receptor agonists have emerged as promising candidates for the treatment of diabetes and obesity. Issues of degradation sensitivity and rapid renal clearance are addressed, for example, by the conjugation of peptides to fatty acid chains, promoting reversible albumin binding. We use combined dynamic and static light scattering to directly measure the self-assembly of a set of dual peptide agonists based on the exendin-4 structure with varying fatty acid chain lengths in terms of apparent molecular mass and hydrodynamic radius (RS). We use NMR spectroscopy to gain an insight into the molecular architecture of the assembly. We investigate conformational changes of the monomeric subunits resulting from peptide self-assembly and assembly stability as a function of the fatty acid chain length using circular dichroism and fluorescence spectroscopy. Our results demonstrate that self-assembly of the exendin-4-derived dual agonist peptides is essentially driven by hydrophobic interactions involving the conjugated acyl chains. The fatty acid chain length affects assembly equilibria and the assembly stability, although the peptide subunits in the assembly retain a dynamic secondary structure. The assembly architecture is characterized by juxtaposition of the fatty acyl side chains and a hydrophobic cluster of the peptide moiety. This cluster experiences local conformational changes in the assembly compared to the monomeric unit leading to a reduction in solvent exposure. The N-terminal half of the peptide and a C-terminal loop are not in contact with neighboring peptide subunits in the assemblies. Altogether, our study contributes to a thorough understanding of the association characteristics and the tendency toward self-assembly in response to lipidation. This is important not only to achieve the desired bioavailability but also with respect to the physical stability of peptide solutions.

Novel approach for overcoming the stability challenges of lipid-based excipients. Part 1: Screening of solid-state and physical properties of polyglycerol esters of fatty acids as advanced pharmaceutical excipients

The major challenge of conventional lipid-based excipients (LBE) for drug delivery is their unstable solid state, affecting the stability of pharmaceutical product. Polyglycerol esters of fatty acids (PGFAs) are oligomeric hydroxyethers of glycerol fully or partially esterified with fatty acids. Tuning the number of polyglycerol moieties, fatty acids chain length and free hydroxyl groups per molecule results in diverse physicochemical properties, e.g. HLB, melting point, and wettability, which makes these molecules attractive candidates as novel LBE for different pharmaceutical applications. In this first part of our studies the solid state of PGFAs and the stability thereof were profiled on molecular, nano, and microstructural level and the resulting properties as LBE. DSC analysis confirmed the single phase system of PGFAs without phase separation. WAXS patterns revealed the absence of polymorphism and the direct crystallization into a stable α-form; without transition to more dense configurations. SAXS patterns exposed the lamellar arrangement. The lamellae stacks were characterized by the crystallite thickness and growth. The nano, microstructure and physicochemical properties of PGFAs remained stable during storage. The stable solid state and the broad functionality of PGFAs offer a novel approach to overcome the challenges faced by conventional LBE for advanced pharmaceutical applications. Examples for such applications are presented in the next parts of this study.

Acid-base-governed deep eutectic solvent-based microextraction combined with magnetic solid-phase extraction for determination of phenolic compounds.

A sensitive method based on the use ofgreen deep eutectic solvents (DESs) was designed for the determination of bisphenol-A, bisphenol-AF, tetrabromobisphenol-A and 4-tert.-octylphenol followed by HPLC. This method takes advantage of magnetic solid-phase extraction purification and acid-base induced DES liquid-liquid microextraction. The Mg(II)-Al(III) layered double hydroxide-coated magnetic nanoparticles were selected to purify samples. The DESs were systematically prepared by a range of medium-chain saturated fatty acids (C8-C12) and D,L-menthol. The melting point and the extraction efficiency of phenolic compounds were adjusted by changing the carbon chain length of fatty acid in suitable proportions. Acid-base induction significantly improves the extraction efficiency. The method has lower limits of detection ranging from 6 to 11ngL-1, good linearity (0.05-500μgL-1) and high enrichment factors (86-91). The method was successfully applied for the determination of four phenolic compounds in beverage samples. The recoveries ranged from 84.4 to 101.3%. Graphical abstract Schematic representation of the extraction of four phenolic compounds by medium chain (C8-C12) fatty acid-based eutectic solvent (DES) through acid-base-induction.