Esterification Rate Research Articles

Enhanced Esterification Performance of Layered SO42−/TiO2‐H3Ti5NbO14 Solid Acid Catalyst

AbstractSO42−/TiO2‐H3Ti5NbOl4 solid acid catalyst was prepared via high‐temperature calcination, proton exchange, pillaring, and impregnation processes. The structures and anchoring model can be confirmed by XRD, SEM, and FT‐IR. The acidic properties and specific surface area were characterized by NH3‐TPD and N2 adsorption‐desorption isotherms. The thermal stability was measured by TG‐DTG. The catalytic performances were evaluated via the esterification reaction of acetic acid and n‐butanol. The results show that SO42−/TiO2‐H3Ti5NbOl4 has stronger acid strength and higher acid content than H3Ti5NbOl4 and TiO2‐H3Ti5NbOl4. The esterification rate of ST‐HTN can be reached at 73.82%. The optimal esterification scheme is as follows: the catalyst dosage is 5 wt%, the molar ratio of alcohol to acid is 1.8:1, the reaction temperature is 127 °C, and reaction time is 5.5 h. Based on the structure‐activity relationship, the esterification properties of the selected catalysts were rationalized, which provided a useful perspective for the development and application of a new generation of esterification catalysts.

Abstract 4138633: Infusion of human apolipoprotein A-I (CSL112) promotes several aspects of reverse cholesterol transport

Background: High-density lipoprotein (HDL)-cholesterol is inversely correlated with cardiovascular risk, but increasing its circulating concentration is insufficient to prevent adverse cardiovascular outcomes. Instead, the emerging paradigm is on increasing the function of HDL and its major protein constituent apolipoprotein A-I (apoA-I), to increase reverse cholesterol transport. Objective: To investigate the effect of apoA-I [human] (CSL112) infusion on HDL protein composition, and provide further insights into the mechanism of action of CSL112 administered post-acute myocardial infarction (AMI). Methods: A mass spectrometry (MS)-based proteomic approach was used to evaluate changes in HDL protein composition in patients (n=50) from the AEGIS-I (ApoA-I Event Reducing in Ischemic Syndromes I) study who received either placebo or CSL112 post AMI. HDL was immuno-isolated from patient plasma using anti-apoA-I antibodies. Cholesterol esterification rate (CER) was measured to determine lecithin-cholesterol acyl transferase (LCAT) activity. Cholesterol efflux capacity (CEC) and hepatocyte uptake were assessed using patient serum in ex vivo cell-based assays. Results: CSL112 induced extensive rearrangement of HDL proteins at 4 hours post-infusion. Levels of apolipoproteins A2, B, C, and E as well as the acute phase proteins serum amyloid A1 and A4 were significantly reduced. By contrast, apoA-I, apoM, and LCAT significantly increased. Elevated apoA-I and LCAT levels on HDL were associated with an increase in CEC, plasma HDL-C levels, and CER in CSL112-treated patients. Furthermore, enhanced CEC strongly correlated with cholesterol uptake by hepatic cells (r=0.95 p<0.001). Conclusion: CSL112 altered HDL composition and increased HDL functionality by promoting multiple steps of the reverse cholesterol transport pathway.

Synthesis of sucrose 6-acetate by immobilized aspergillus Niger lipase imprinted with oleic acid and sorbitol

Biological and interfacial imprinting both were effective methods to improve the catalytic performance of lipase in organic solvent. Bioimprinting combined with interfacial activation of lipase was investigated for obtaining imprinted lipase with excellent catalytic performance. Enzymatic synthesis of sucrose-6-acetate in organic solvents to test the performance of imprinted lipase immobilized by adsorbing on macroporous resin. Lipase imprinted by substrate analog (oleic acid) then immobilization catalyzed the synthesis of sucrose-6-acetate with a 1.7 times increase in sucrose esterification rate compared to unimprinted immobilized lipase and a selectivity toward sucrose-6-acetate of 91.7 %. The sucrose esterification rate of reaction catalyzed by immobilized lipase was increased to 2.0 times with addition of sorbitol after imprinting by oleic acid. Imprinting by oleic acid and interfacial effect generated by oleic acid with sorbitol both induced zymoprotein secondary structure change that were conducive to enhance catalytic activity and stability of lipase in organic solvent.

Influence of pH on the synthesis of carbon spheres and the application of carbon sphere-based solid catalysts in esterification

Abstract Size uniformity is a key challenge in the preparation of hydrothermal carbon spheres and a prerequisite for size effect research and many applications of carbon spheres. To solve the scientific problem of low uniformity due to the slow carbonization in traditional preparation of glucose carbon spheres, we propose to add acid/base catalysts to accelerate nucleation, shorten the nucleation time, and improve the size uniformity of carbon spheres. The carbon spheres prepared under base conditions versus acid conditions have higher uniformity and smaller particle size (particle size = 503 nm). This result is due to the faster accumulation of aromatic clusters, shorter nucleation time, and larger number of carbon spheres in alkaline systems. The NaOH-HCSs-based solid acid catalyst as-prepared exhibits excellent catalytic activity, and the esterification rates of levulinic acid and n-butanol maximize to 96.36%.

Heteropolyacids combined with Y zeolite as superior solid acid catalysts to accelerate lactic acid esterification

AbstractBACKGROUNDEthyl lactate produced via esterification between lactic acid and ethanol can be used in plastics, polymers and food industries and renowned for its biodegradability and low toxicity. However, lactic acid self‐catalyzed esterification presents a slow reaction process, and acid catalysts are needed to improve the catalysis. Homogeneous acid catalysts like H2SO4 are corrosive, as well as being difficult to be seperated from the reaction media; therefore, advanced heterogeneous catalysts are more ideal. In this study, two kinds of heteropolyacid–zeolite catalysts, involving loading silicotungstic acid and phosphotungstic acid onto Y zeolite, were synthesized, characterized using X‐ray diffraction, NH3 temperature‐programmed desorption and scanning electron microscopy and analyzed for their catalytic efficiency in the catalytic esterfication.RESULTSResults showed that the Keggin structures of heteropolyacids were retained during the preparation process and strong acid sites of Y zeolite were enriched, which made the main contribution to the esterification of lactic acid and ethanol. Furthermore, the initial‐stage reaction rate of esterification was significantly enhanced. During the first hour of esterification, the conversion of lactic acid increased from 18% to 65%. Exp Dec1 index model was employed to determine the activation energies of 60HSiW‐Y and 60HPW‐Y, which exhibit values of 29.3 and 28.2 kJ mol−1, respectively.CONCLUSIONThis study indicates that Keggin structures of heteropolyacids play a key role in the esterification and heteropolyacid–zeolite catalysts can effectively catalyze the esterification. Meanwhile, the results of the kinetic experiments can be of reference significance for large‐scale industrial processes involving esterification. © 2024 Society of Chemical Industry (SCI).

Biocatalytic synthesis of L-ascorbyl palmitate using oleic acid imprinted Aspergillus niger lipase immobilized on resin

In order to improve the esterification efficiency of the enzymatic synthesis of l-ascorbic acid palmitate, the substrate analogue imprinting of the Aspergillus niger lipase-catalyzed esterification process was studied. Oleic acid was selected as the imprinting molecule, oleic acid imprinting immobilized lipase was prepared at pH 8.0, 0.1 g oleic acid, 1.5 mL of 95 % ethanol, and 0.1 g Tween-20. Through solubilization and supersaturation of Vitamin C, the reaction concentration of Vitamin C reached 5.00 % (m/v) in dioxane with 93.99 % esterification rate and 110.72 g/L of product concentration. Moreover, the Vitamin C reaction concentration can reach 8.00 % by using staged substrate feeding, and the esterification rate and product concentration of esterification after 28 h was 156.34 g/L and 82.96 %. Besides, the imprinting-induced conformational changes in enzyme proteins was characterized by fluorescence and infrared spectroscopy. This method provides a pathway for enzymatic production of l-ascorbic acid palmitate.

Ethyl Cyanoacetate Reactions

Ethyl cyanoacetate is a chemical intermediate that has been frequently used. The esterification of cyanoacetic acid and absolute ethanol with a mixed catalyst yielded ethyl cyanoacetate (the same proportion of silicotungstic and p-toluene sulfonic acid as catalyst). The influence factors of the amount of catalyst, n (cyanoacetic acid): n (absolute ethanol), reaction time and reaction temperature on the esterification rate was investigated by orthogonal experiment of four factors and three levels. The product was analyzed by gas chromatography to determine the optimum reaction conditions

Cholesterol esterification is hampered in alzheimer’s disease and cholesteryl esters composition is consequently altered

Introduction and Aim: Several epidemiological studies indicate a strong inverse association between the risk of developing Alzheimer’s disease (AD) and plasma HDL-C levels. The mechanism by which plasma HDL influence the pathogenesis and progression of AD is still unsolved and since cholesterol esterification is a crucial step in HDL metabolism it could be involved. The purpose of this study was to evaluate cholesterol esterification and HDL subclasses in plasma and cerebrospinal fluid (CSF) of Alzheimer’s Disease (AD) patients. Methods: The study enrolled 70 AD patients and 74 cognitively-normal controls comparable for age and sex. Lipids and lipoprotein profile, cholesterol esterification, and cholesterol efflux capacity (CEC) were evaluated in plasma and CSF using assays set for measurement in plasma, which were appropriately modified for CSF. Results: AD patients have normal plasma lipids, but significantly reduced unesterified cholesterol and unesterified/total cholesterol ratio. Lecithin:cholesterol acyltransferase (LCAT) activity and cholesterol esterification rate (CER), two measures of the efficiency of the esterification process, were reduced by 29% and 16%, respectively, in plasma of AD patients. Plasma HDL subclass distribution in AD patients was comparable to that of controls, but the content of small discoidal preβ-HDL particles was significantly reduced. In agreement with the reduced preβ-HDL particles, cholesterol efflux capacity mediated by the transporters ABCA1 and ABCG1 was reduced in AD patients’ plasma. The CSF unesterified to total cholesterol ratio was increased in AD patients, and CSF CER and CEC from astrocytes were significantly reduced in AD patients. In the AD group, a significant positive correlation was observed between plasma unesterified cholesterol and unesterified/total cholesterol ratio with Aβ1-42 CSF content. Conclusions: Taken together data indicate that cholesterol esterification is hampered in plasma and CSF of AD patients, and that plasma cholesterol esterification biomarkers (unesterified cholesterol and unesterified/total cholesterol ratio) are significantly associated to disease biomarkers (i.e., CSF Aβ1-42).

Magnetic biocatalytic nanoreactors based on graphene oxide with graded reduction degrees for the enzymatic synthesis of phytosterol esters

As we know, the carriers of enzymatic nanoreactors with different amphipathy have significant influence on the interfacial enzyme activities and its performance. In this study, the magnetic graphene oxide (GO) enzyme carriers were constructed by assembling graphene oxide with different reduction degrees (rGO(x)) and polyethyleneimine (PEI) modified nano-flowery Fe3O4 into composite materials through electrostatic interactions, and x here represents the reduction reaction hours of GO. The SEM, TEM, contact angles and BET tests qualified the ideal enzyme carrier, PEI-Fe3O4-rGO(12), by adsorption-crosslinking method, the Candida rugosa lipase (CRL) was immobilized to obtain the lipase nanoreactor, PEI-Fe3O4-rGO(12)@CRL. The nano-sheet and nano-flower structures provided a larger specific surface area and suitable pore size, and the CRL had higher protein load on the carrier material (163.11 mg/g). In addition, using hydrolyzed p-nitrophenol palmitate as the model, the PEI-Fe3O4-rGO(12)@CRL can still show 76.5 % residual activity after 8 repeated uses. At the same time, the immobilized lipase showed good catalytic performance in the biosynthesis of phytosterol esters. The optimal esterification conditions were determined by single factor experiment (isooctane, sterol concentration 150 μmol/mL, alkyd molar ratio 1:2, enzyme dosage 120 mg, 26 h, 55 °C, the esterification rate was 76.24 %). Therefore, the optimal biocatalyst PEI-Fe3O4-rGO(12)@CRL may has good performance in the biosynthesis of other novel foods.

Enhanced Esterification Activity and Thermostability of Imprinted Poly(Ethylene Glycol)-Lipase Complex

Although the range of applications for enzymatic reactions in organic solvents is <br /> rapidly expanding, this study focused on the enzymatic activity in the esterification of <br /> lauric acid with benzyl alcohol, and thermostability of lipase using poly(ethylene glycol) <br /> (PEG)-lipase complex and molecular imprinting techniques. The catalytic activity was <br /> enhanced through molecular imprinting and the PEG-lipase complex. The imprinting operation was particularly effective for catalytic activity after forming the PEG-lipase complex. The kinetic analysis of the lipase-catalyzed esterification revealed that the increase in esterification rate with imprinted lipases was mainly due to the higher maximum rate achieved by the system. The thermostability of the lipases was significantly improved by imprinting at all temperatures (50~70 °C). After forming a PEG-lipase complex, the imprinted lipase exhibited much higher reactivity and thermostability compared to the native lipase and the imprinted PEG-lipase complex.

Rice bran phytosterol nanoparticles: A promising approach to enhance yogurt quality and nutrition

AbstractThis study aimed to improve the comprehensive utilization value of rice bran by investigating catalysts for the methyl esterification reaction of rice bran oil deodorized distillates and preparing phytosterol nanoparticles for addition to yogurt. Fe2(SO4)3 was found to be an effective catalyst, achieving a methyl esterification rate of 98.07 ± 0.23% under optimal conditions. Then, phytosterol nanoparticles were prepared and added to yogurt, resulting in stable addition with the pH decreased from 4.23 ± 0.01 to 4.02 ± 0.01 and the titratable acidity increased from 106.48 ± 0.85 °T to 117.07 ± 0.82 °T during storage. The addition of phytosterol nanoparticles increased the apparent viscosity from 0.68 ± 0.01 Pa s to 0.72 ± 0.02 Pa s and the G* from 80.01 ± 5.50 Pa to 91.80 ± 1.99 Pa, resulting in thicker and more elastic texture. Phytosterol nanoparticle improves the dispersion and stability of phytosterols in yogurt, thus making it stable to be added to yogurt. Fe2(SO4)3 is a suitable catalyst for the methyl esterification reaction of rice bran oil deodorized distillates, and the addition of rice bran phytosterol nanoparticles to yogurt can enhance its texture and nutritional value, offering a promising strategy for producing high value‐added products from rice bran.

Effect of the water content and the lengthening of fatty acids chain on the iCALB‐catalyzed esterification in deep eutectic solvents

AbstractFour Deep Eutectic Solvents (DES) based on choline chloride (ChCl) and different hydrogen bond donors (1,4‐butanediol, glycerol, isosorbide, and urea) were tested as reaction medium for the immobilized Candida antarctica B (iCALB) lipase‐catalyzed esterification of fatty acids with n‐butanol. Although the strong hydrogen bonds between DES components were expected to lower their reactivity, all except urea, competed in the esterification reaction. To study the effect of acyl group donor and water, different chain length of saturated fatty acids (ranging from 6:0 to 18:0) and water content (ranging from 0, 1, 2 or 3 molar ratio of water/ChCl) were tested in the lipase‐catalyzed esterification with n‐butanol in ChCl:urea (1:2, molar ratio). When the incubation was performed in the absence of water, the shorter the fatty acid chain length, the higher the conversion. Upon water addition, a drastic increase in the esterification rate of all the fatty acids was observed and, conversely to what occurred in the anhydrous media, the longer the fatty acid chain length, the higher the conversion. Results suggest that water concentration in the DES medium possesses a multifactorial effect, as it influences the enzyme activity, the solvent viscosity, the DES structure, and the interaction between DES components, substrates, and enzymes, thus determining the efficiency and yield of the esterification reaction.

Preparation of vacuum-assisted conjugated linoleic acid phospholipids under nitrogen: Mechanism of acyl migration of lysophospholipids

Sn-Glycerol-3-phosphatidylcholine (GPC) was prepared by hydrolysis of phosphatidylcholine (PC) catalyzed by phospholipase A1 (PLA1). Nitrogen flow assisted the esterification of conjugated linoleic acid (CLA) and GPC to produce conjugated linoleic acid lysophosphatidylcholine (LPC − CLA). The effects of different reaction conditions on the PC conversion and acyl migration rates were investigated, and the acyl migration mechanism under acidic and alkaline conditions was studied. In addition, the optimum conditions for the esterification of CLA and GPC were selected. The optimal condition for the hydrolysis of PC was an enzyme loading of 5 %, pH of 5, reaction temperature of 50 ℃, and reaction time of 3 h. The results also showed that the maximum esterification rate reached 82.37 % at an enzyme loading of 15 %, CLA/GPC molar ratio of 50:1, and vacuum pressure of 13.3 kPa. This study not only improved the bioavailability of PC but also effectively increased the content of LPC − CLA.

TRANSMISSION OF POLAR SUBSTITUENT EFFECTS IN 4`-SUBSTITUTED DIPHENYLACETYLENE-4-CARBOXYLIC ACIDS

A series of 4'-substituteddiphenylacetylene-4-carboxylic acids' alkaline hydrolysis rate coefficients were measured in 70%(v/v) dimethyl sulfoxide- water at 30.0 C. Using a solution of 80% (w/w) 2-methoxyethanol - water at 25.0 C, the pKa values of 4'- substituted diphenylacetylene-4-carboxylic acids have been determined. Esterification rate constants of corresponding acids with diazodiphenylmethane have been measured at 300C. For the transmission of dipolar ireversible dipolar substituent effects were seen for 4' - substituted diphenylacetylene-4-carboxylic acids. it was normal substituent effects are observed from 4`-substituted diphenylacetylene-4-carboxylic acids .Therefor it is conceivable to explain clearly the polar of substituent effect of the transmission via path of direct field of electrostatic in this system according to the results shown in tables 8,10 and 12

Apolipoprotein E isoforms differentially affect LCAT-dependent cholesterol esterification

Background and aimsLCAT esterifies cholesterol in both HDL (α-activity) and apoB-containing lipoproteins (β-activity). The main activator of LCAT β-activity is apoE, which in humans exists in 3 main different isoforms (E2, E3 and E4). Here, to gather insights into the potential role of LCAT in apoB-containing lipoprotein metabolism, we investigated the ability of apoE isoforms to promote LCAT-mediated cholesterol esterification. MethodsWe evaluated the plasma cholesterol esterification rate (CER) in 311 individuals who express functional LCAT and either apoE2, apoE3, or apoE4 and in 28 individuals who also carried LCAT mutations causing selective loss of LCAT α-activity (Fish-Eye Disease (FED)-causing mutations). The association of carrier status with CER was determined using an adjusted linear regression model. The kinetic of LCAT activity towards reconstituted HDLs (rHDLs) containing each apoE isoform was determined using the Michaelis-Menten model. ResultsPlasma CER was ∼20% higher in apoE2 carriers compared to apoE3 carriers, and ∼30% higher in apoE2 carriers compared to apoE4 carriers. After adjusting for age, sex, total cholesterol, HDL-C, apoA-I, apoB, chronic kidney disease diagnosis, zygosity, and LCAT concentration, CER remained significantly different among carriers of the three apoE isoforms. The same trend was observed in carriers of FED-causing mutations. rHDLs containing apoE2 were associated with a lower affinity but higher maximal esterification rate, compared to particles containing apoE3 or apoE4. ConclusionThe present results suggest that the apoE2 isoform is associated with a higher LCAT-mediated cholesterol esterification. This observation may contribute to the characterization of the peculiar functional properties of apoE2.

Enhanced esterification performance by SO42−/ZrO2 anchored Nb2O5 nanotube

SO42-/ZrO2 anchored Nb2O5 nanotubes (SO42-/ZrO2@Nb2O5-NT) are prepared via the high temperature calcination, proton exchange, exfoliation, recombination, and impregnation processes. The structures and anchoring model can be confirmed by XRD, HRTEM, and FT-IR technologies. The acidic properties and specific surface area are characterized by NH3-TPD and N2 adsorption–desorption isotherms. The catalytic performances are evaluated via an esterification reaction of acetic acid and n-butanol. The results show that SO42-/ZrO2@Nb2O5-NT have stronger acid strength and higher acid content than that of Nb2O5-NT. The optimal esterification scheme is as follows: catalyst dosage is 11 wt.%, molar ratio of alcohol to acid is 2.7:1, reaction temperature is 118 ℃, and reaction time is 7 h. The esterification rate can be reached up to 92.31% over SO42-/ZrO2@Nb2O5-NT. We have rationalized esterification performance of these selected catalysts in light of structure–property relationships, which gives useful insight for the development and application of next generation esterification catalyst.

Fabrication and characterization of light-curing soybean oil-based epoxy resin applied for LCD additive manufacturing

In this work, we developed a photocurable vegetable oil-based resin with suitable curing properties for use in 3D printing. The acrylated epoxidized soybean oil (AESO), which was synthesized by the catalytic ring-opening reaction of the epoxidized soybean oil (ESO) and acrylic acid (AA), replaced the oligomer in conventional light-curing petroleum-based resins. In order to optimize the various properties of the soybean oil-based epoxy resin, the performance parameters of the resin were analyzed by numerical simulation. It was also combined with the parameters of the printing equipment to better guide the 3D printing process of the resin. The results showed that the esterification rate of acrylic acid (AA) with epoxidized soybean oil (ESO) was higher than that of methacrylic acid (MAA) during the arylation of epoxidized soybean oil (ESO), and AESO had moderate viscosity and was suitable as an oligomer for 3D printing. When the diluent of the oligomer has an ACMO to HDDA ratio of 3:2, the cured parts exhibit the optimum mechanical properties, hydrophobic properties, and thermal stability. All properties of the resins were further improved and giving the formulation the best 3D printing performance when 10% of epoxy resin E44 was added to the soybean oil-based epoxy resin. In addition, the numerical simulations indicate that this soybean oil-based epoxy resin formulation has the highest printing efficiency when the single layer thickness of the cured layer is set to 0.2 mm with the exposure time of 4 s, where the wavelength of UV is 405 nm and the light intensity is 40 W/m2. In conclusion, the light-curing resin developed through the soybean oil-based epoxy resin exhibits excellent performance in all aspects. The optimal printing process was also derived by combining the results obtained from numerical simulations of the resin performance parameters with the device parameters, which significantly improved the efficiency of the 3D printing with the fabricated soybean oil-based epoxy resin, making it has great application potential for the biomedical materials.

Effect of Chemical Pre-Treatment on the Catalytic Performance of Oil Palm EFB Fibre Supported Magnetic Acid Catalyst

The development of heterogenous catalysts using renewable materials has received wide attention. A heterogenous catalyst has been a preferred choice as it evades the disadvantages of homogeneous catalysts, nevertheless, heterogenous catalysts has limited activity and a longer separation process. The current study emphasises the preparation of a new magnetic catalyst using oil palm empty fruit bunch (EFB) fibre as a carbon-based support material. The effect of different alkaline pre-treatments over the methyl ester conversion rate were investigated. The catalyst preparation parameters were studied by using the single factor optimisation approach, including the fibre loading, impregnation time, calcination temperature, and calcination time. Their effects in the esterification of oleic acid were investigated in this study. The optimisation study shows that the Na2CO3-treated(T)-EFBC magnetic catalyst had the highest esterification rate of 93.5% with 7 g EFB fibre loading, a 2 h impregnation time and a calcination temperature of 500 °C for 2 h. The catalyst possessed a good acidity of 3.5 mmol/g with excellent magnetism properties. This study showed that the catalysts are magnetically separable and exhibited good stability with 82.1% after five cycles. The oil palm EFB supported magnetic acid catalyst indicates it as a potential option to the existing solid catalysts that is economical and environmentally friendly for the esterification process.

Synthesis of polyglycerol fatty acid esters catalyzed by lipase and evaluation of its emulsification properties

The present study investigated the physicochemical properties of the newly synthesized polyglycerol fatty acid esters (PGFEs) and their potential application as food emulsifiers. It turned out that the complete removal of glycerol from crude polyglycerol was achieved by optimizing the molecular distillation temperature (120 °C). Moreover, novozym 435 was used to catalyze the synthesis of PGFEs with different aliphatic chain lengths, and the esterification rate of the obtained products was 93%∼98%. The characteristic absorption peak of the ester carbonyl group was displayed at 1738 cm−1, and that of C–O–C on the ether bond was at 1100 cm−1 and 1048 cm−1. Therefore, the synthesis can be determined to be PGFEs. Their hydrophilic lipophilic balance (HLB) values are >7, which can be used as oil-in-water emulsifiers. When curcumin nanoemulsions were constructed by PGFEs with various aliphatic chains as emulsifiers, it was found that all PGFEs in C10∼C18 can form stable curcumin nanoemulsions (encapsulation rate was >95%). PGFEs with longer aliphatic chains can stabilize nanoemulsions more efficiently (larger droplet sizes and lower ζ-electric potential), and showed better storage and UV stability. Whereas, medium-chain PGFEs emulsions, especially PGC, showed the best curcumin release efficiency, which theoretically supported the application of PGFEs to functional emulsion products.

Plasma and cerebrospinal fluid cholesterol esterification is hampered in Alzheimer’s disease

ObjectiveThe purpose of this study was to evaluate cholesterol esterification and HDL subclasses in plasma and cerebrospinal fluid (CSF) of Alzheimer’s disease (AD) patients.MethodsThe study enrolled 70 AD patients and 74 cognitively normal controls comparable for age and sex. Lipoprotein profile, cholesterol esterification, and cholesterol efflux capacity (CEC) were evaluated in plasma and CSF.ResultsAD patients have normal plasma lipids but significantly reduced unesterified cholesterol and unesterified/total cholesterol ratio. Lecithin:cholesterol acyltransferase (LCAT) activity and cholesterol esterification rate (CER), two measures of the efficiency of the esterification process, were reduced by 29% and 16%, respectively, in the plasma of AD patients. Plasma HDL subclass distribution in AD patients was comparable to that of controls but the content of small discoidal preβ-HDL particles was significantly reduced. In agreement with the reduced preβ-HDL particles, cholesterol efflux capacity mediated by the transporters ABCA1 and ABCG1 was reduced in AD patients’ plasma. The CSF unesterified to total cholesterol ratio was increased in AD patients, and CSF CER and CEC from astrocytes were significantly reduced in AD patients. In the AD group, a significant positive correlation was observed between plasma unesterified cholesterol and unesterified/total cholesterol ratio with Aβ1-42 CSF content.ConclusionTaken together our data indicate that cholesterol esterification is hampered in plasma and CSF of AD patients and that plasma cholesterol esterification biomarkers (unesterified cholesterol and unesterified/total cholesterol ratio) are significantly associated to disease biomarkers (i.e., CSF Aβ1-42).