Lipase-catalyzed Transesterification Research Articles

Effect of Reaction Parameters on the Lipase-Catalyzed Kinetic Resolution of (RS )-Metoprolol

Racemic metoprolol is a selective ß1-blocker, which is used in cardiovascular disease treatment. It has been found that (S)-metoprolol has a higher affinity to bind the ß-adrenergic receptor compared to (R)-metoprolol. Moreover, the regulatory authorities’ high market demand and guidelines have increased the preference for single enantiomer drugs. In this work, the lipase-catalyzed kinetic resolution of racemic metoprolol was performed to obtain the desired enantiomer. The type of lipase, acyl donor, and solvent were screened out. This was achieved by Candida antarctica B lipase-catalyzed transesterification of racemic metoprolol in hexane and vinyl acetate as the solvent and an acyl donor, which gave maximum conversion of (S)-metoprolol (XS) of 52%, enantiomeric excess of substrate, (ees) of 92% and product (eeP) of 90% with enantiomeric ratio (E) of 62. This method can be considered as green chemistry, which can be applied to produce other enantiopure beta-blockers.

Continuous Production of 2-Phenylethyl Acetate in a Solvent-Free System Using a Packed-Bed Reactor with Novozym® 435

2-Phenylethyl acetate (2-PEAc), a highly valued natural volatile ester, with a rose-like odor, is widely added in cosmetics, soaps, foods, and drinks to strengthen scent or flavour. Nowadays, 2-PEAc are commonly produced by chemical synthesis or extraction. Alternatively, biocatalysis is a potential method to replace chemical synthesis or extraction for the production of natural flavour. Continuous synthesis of 2-PEAc in a solvent-free system using a packed bed bioreactor through immobilized lipase-catalyzed transesterification of ethyl acetate (EA) with 2-phenethyl alcohol was studied. A Box–Behnken experimental design with three-level-three-factor, including 2-phenethyl alcohol (2-PE) concentration (100–500 mM), flow rate (1–5 mL min−1) and reaction temperature (45–65 °C), was selected to investigate their influence on the molar conversion of 2-PEAc. Then, response surface methodology and ridge max analysis were used to discuss in detail the optimal reaction conditions for the synthesis of 2-PEAc. The results indicated both 2-PE concentration and flow rate are significant factors in the molar conversion of 2-PEAc. Based on the ridge max analysis, the maximum molar conversion was 99.01 ± 0.09% under optimal conditions at a 2-PE concentration of 62.07 mM, a flow rate of 2.75 mL min−1, and a temperature of 54.03 °C, respectively. The continuous packed bed bioreactor showed good stability for 2-PEAc production, enabling operation for at least 72 h without a significant decrease of conversion.

Desirability function approach for optimization of enzymatic transesterification catalyzed by lipase immobilized on mesoporous magnetic nanoparticles

Abstract Lipase-catalyzed transesterification for biodiesel production is clean, effective and water tolerance compare with conventional chemical or physical biodiesel synthesis methods. Therefore, in the present research, Burkholderia cepacia lipase was immobilized onto mesoporous silica/iron oxide magnetic core-shell nanoparticles for canola waste cooking oil (WCO) conversion to biodiesel. Response Surface Methodology (RSM) with Central Composite Design (CCD) was used to optimize the transesterification parameters. A quadratic polynomial equation was obtained for biodiesel yield by multiple regression analysis. Desirability function approach gave the optimal transesterification condition as: immobilized lipase concentration of 36%, reaction time of 25 h, methanol to WCO molar ratio of 6.2 and reaction temperature of 34 °C. The predicted biodiesel yield was 92% at the optimal condition. Transesterification catalyzed by the immobilized lipase carried out three times repeatedly, by losing just 11% of lipase activity in the third cycle of the transesterification.

Amphiphilic dextran-vinyl laurate-based nanoparticles: formation, characterization, encapsulation, and cytotoxicity on human intestinal cell line.

Dextran has been the model material for the therapeutic applications owing to its biodegradable and biocompatible properties, and the ability to be functionalized in variety of ways. In this study, the amphiphilic dextran was successfully synthesized through lipase-catalyzed transesterification between dextran and vinyl laurate. In aqueous solution, the produced dextran ester could self-assemble into spherical nanoparticles ("Dex-L NPs") with approximately 200-nm diameter, and could incorporate porcine placenta hydrolysate with 60% encapsulation efficiency. Furthermore, Dex-L NPs exhibited low cytotoxic effects on human intestinal cell line and, thus, were potentially safe for oral administration. Taken together, the findings illustrate the potential of the newly developed nanoparticles to serve as an efficient and safe drug delivery system.

Synthesis of Lipase-Immobilized CeO2 Nanorods as Heterogeneous Nano-Biocatalyst for Optimized Biodiesel Production from Eruca sativa Seed Oil

Biodiesel has emerged as one of the most attractive alternative energy sources to meet the growing needs of energy. Many approaches have been adopted for biodiesel synthesis. In the present work, biodiesel was produced from non-edible Eruca sativa oil using nano-biocatalyst-catalysed transesterification. Nano-biocatalyst (CeO2@PDA@A. terreus Lipase) was developed via the immobilization of lipase on polydopamine coated ceria nanorods, and CeO2 nanorods were developed via a hydrothermal process. The mean diameter of nanorods were measured to be 50–60 nm, while their mean length was 150–200 nm. Lipase activity before and after immobilization was measured to be 18.32 and 16.90 U/mg/min, respectively. The immobilized lipase depicted high stability at high temperature and pH. CeO2@PDA@A. terreus Lipase-catalysed transesterification resulted in 89.3% yield of the product. Process optimization through response surface methodology was also executed, and it was depicted that the optimum/maximum E. sativa oil-based biodiesel yield was procured at conditions of 10% CeO2@PDA@A. terreus Lipase, 6:1 methanol/oil ratio, 0.6% water content, 35 °C reaction temperature, and 30 h reaction time. The fuel compatibility of synthesized biodiesel was confirmed via the estimation of fuel properties that were in agreement with the ASTM D standard. The nanorods and dopamine-modified nanorods were characterized by FTIR spectroscopy, SEM, and energy dispersive X-ray (EDX), while conversion of E. sativa oil to biodiesel was confirmed by GC/MS and FTIR spectroscopy. Conclusively, it was revealed that CeO2@PDA@A. terreus Lipase has potential to be employed as an emphatic nano-biocatalyst.

Enzymatically derived oil-based L-ascorbyl esters: Synthesis, antioxidant properties and controlled release from cosmetic formulations

Lipase-catalyzed transesterification of vitamin C by natural triglycerides is promising approach for cost-efficient synthesis of liposoluble food and cosmetic antioxidants. Nevertheless, application of these alternative acyl donors is insufficiently explored, despite of their low price, wide abundance and possibility for obtaining versatile products. Within current study, fatty acid ascorbyl esters were synthesized from vitamin C and natural triglycerides (lard, sunflower, coconut and linseed oil) in a process catalyzed by immobilized lipase Novozym® 435 and their controlled release was examined. High conversions were achieved at optimized conditions, even at high substrate concentrations, thus high concentrations of acsorbyl-ester were synthesized using these natural lipids. All ester mixtures exhibited very high capacity for scavenging of DPPH radicals, among which linseed oil derived esters, with ascorbyl linolenate as prevailing compound, were the most efficient (IC50 0.663 μM), while coconut oil derived ester mixture (IC50 0.739 μM), composed predominantly of molecules with medium side chains, was second best. Coconut oil derived esters were successfully incorporated in typical cosmetic formulations for controlled release of bioactive compounds - O/W emulsion and gel-emulsion. Franz cell diffusion study demonstrated that esters release from mixture and two carrier systems was formulation dependent and revealed decrease of effective diffusivities with ester side acyl chain length increase. According to calculated effective diffusivity coefficients, faster trans-membrane delivery of the same molecule was achieved from gel-emulsion comparing to O/W emulsion. Applied approach enabled highly efficient cost-saving production of fatty acid ascorbyl esters, which could find direct application in various lipophilic products.

Optimization of Enzymatic Synthesis of Neryl Acetate in a Solvent Free System

Synthesis of valuable flavour and fragrance compounds is one of the intense applications of lipase-catalysed transesterification. This paper demonstrated application of Novozyme 435 to the synthesis of neryl acetate in a solvent free system. Response surface methodology (RSM) complemented by central com-posite design (CCD) was used to evaluate the effect of various process param-eters on reaction conversion. The results showed that 91.6% conversion of nerol with 100% selectivity to neryl acetate was obtained under the conditions of 1:12.6 mole ratio of nerol to ethyl acetate, 2.6% (w/w) Novozyme 435 at 52.7?C for 2 h. From the kinetic study, it was verified that the reaction followed a ternary complex mechanism with inhibition by ethyl acetate. The process was green, clean and useful to the perfume and flavour industries.

Biodiesel-mediated biodiesel production: A recombinant Fusarium heterosporum lipase-catalyzed transesterification of crude plant oils

Production of biodiesel from unrefined plant-derived oils has been considerably investigated but, to date, there appears to be a limit by phospholine gums and other contaminants in its conversion to biodiesel. The presence of such contaminants increases the melting point of the oils, thereby, making it unfavorable for lipase-catalyzed reactions at mild temperatures. Here, to circumvent this limiting effect, we explore the potential of biodiesel as a replacement for conventional organic solvents in solubilizing gum-formation contaminants in crude palm oil (CPO). A strategy of 1:1 CPO/biodiesel molar amount consolidates degumming and trans/esterification into one-step using immobilized Aspergillus oryzae expressing Fusarium heterosporum lipase. The innocuous biodiesel solvent not only ensured a 98.8 wt% biodiesel yield but also improved the catalytic activity of the whole-cell lipase. This allowed repeated use of the recombinant lipase in nine consecutive batches. At room temperature, biodiesel as a solvent saves on post-separation and reduces environmental footprints of the biodiesel production process.

Regioselective Acylation of Levoglucosan Catalyzed by Candida Antarctica (CaLB) Lipase Immobilized on Epoxy Resin

Every year, a large amount of residual agroindustrial waste has been generated and only around 10% is in fact reused. The development of new strategies for biomass valorization is important to add value to these commodities, since biomass is an excellent alternative feedstock to obtain chemicals of interest from renewable resources. The major compound of pyrolytic treatment of lignocellulosic biomass is levoglucosan (1,6-anhydroglucopyranose), an anhydro-sugar that can be transformed into glucose and is greatly valued in the most diverse industrial sectors as a surfactant, emulsifier, or even a lubricant. In this work, levoglucosan was acylated by lipase-catalyzed transesterification in acetonitrile with great conversions and selectivities with different acyl donors such as ethyl esters of lauric, palmitic, stearic, and oleic acids prepared in situ in an integrated strategy mediated by commercial lipases Novozym435 (N435), PSIM, and the home-made biocatalyst CaLB_epoxy. As a result, all biocatalyst generated mostly monoesters, with N435 being more selective to produce lauric esters (99% at 50°C) and PSIM to produce oleic esters (97% at 55 °C) while CaLB_epoxy was more selective to produce oleic esters of levoglucosan (83% at 55°C). This is the first report in the literature on the production of high selectivity levoglucosan esters.

Preparation of water-in-oil microemulsion-based lacquer wax isopropyl ester and its UVA and UVB protection characteristics

Lacquer wax represents a significant resource derived from the berries of Toxicodendron vernicifluum in China. The main chemical component of lacquer wax is fatty acid. The fatty acid isopropyl ester prepared from this acid has played a role in enhancing skin penetration and spreading properties, which makes it suitable for use as an important material in washing, cosmetics, and pharmaceuticals. In this study, the isopropyl ester of lacquer wax was synthesized by lipase-catalyzed transesterification for the first time ever. In addition, microemulsion of lacquer wax-based isopropyl ester (LW-IPE) was prepared by adding surfactant, co-surfactant, and water to solve the flocculation phenomenon of LW-IPE. The microemulsion was characterized by its stability, conductivity, viscosity, and particle size, which confirmed the formula of water-in-oil (W/O) microemulsion. The W/O microemulsion demonstrated an excellent thermodynamic stability in the temperature range between 20 °C and 40 °C and was stabilized with the addition of NaCl. In vitro evaluation of protection against ultraviolet light (UVA and UVB) demonstrated that arbutin in W/O microemulsion is capable to protect against UVA. This study is believed as providing valuable information on the performance of microemulsion systems suitable for use in the cosmetics and pharmaceuticals industries.

Insight into the Modification of Phosphatidylcholine with n-3 Polyunsaturated Fatty Acids-Rich Ethyl Esters by Immobilized MAS1 Lipase.

This study reported the modification of phosphatidylcholine (PC) with n-3 polyunsaturated fatty acids (PUFA)-rich ethyl esters (EE) by immobilized MAS1 lipase-catalyzed transesterification in the solvent-free system. Effects of n-3 PUFA-rich EE/PC mass ratio, enzyme loading, reaction temperature, and water dosage on the incorporation of n-3 PUFA into PC were investigated, respectively. The results indicate that the maximum incorporation of n-3 PUFA into PC reached 33.5% (24 h) under the following conditions: n-3 PUFA-rich EE/PC mass ratio of 6:1, enzyme loading of 20%, reaction temperature of 55 °C, and water dosage of 1.0%. After 72 h of reaction, the incorporation of n-3 PUFA into PC was 43.55% and the composition of the reaction mixture was analyzed by 31P nuclear magnetic resonance (NMR). The results show that the reaction product consisted of 32.68% PC, 28.76% 1-diacyl-sn-glycero-3-lysophosphatidylcholine (sn-1 LPC), 4.90% 2-diacyl-sn-glycero-3-lysophosphatidylcholine (sn-2 LPC), and 33.60% sn-glycero-3-phosphatidylcholine (GPC). This study offers insight into the phospholipase activity of immobilized MAS1 lipase and suggests the extended applications of immobilized MAS1 lipase in the modification of phospholipids for industrial purpose.

Kinetic model of resolution of 4-methoxymandelic acid enantiomers by lipase-catalyzed transesterification reaction

This paper reports the kinetics resolution of (R,S)-4-methoxymandelic acid (4-MMA) by lipase AK-catalyzed transesterification reaction, using vinyl acetate (VA) as acyl donor in methyl tert-butyl ether (MTBE). Considering the Ping-Pong bi-bi mechanism with 4-methoxymandelic acid inhibition, the kinetic model was established. Kinetic parameters were obtained by fitting time-concentration curves for different initial 4-methoxymandelic acid concentrations. The average relative error below 3.0% indicated that the model predictions were in good agreement with the experimental data. Furthermore, the kinetic model was employed to predict the effects of enzyme loading, initial vinyl acetate concentration and reaction time on enantiomeric excess (ees) and conversion of substrate (c), and to optimize the conditions. The excellent results with high conversion of 4-MMA (50.2%) and large enantiomeric excess of substrate (98.6%) were achieved under the optimal conditions.

A Density Functional Theory (DFT) Study of the Acyl Migration Occurring during Lipase-Catalyzed Transesterifications.

Acyl migration (AM) is the main side reaction in the large-scale, regio-specific lipase catalyzed production of structural triglycerides (STs). A detailed understanding of the mechanism of AM was obtained during the process of lipase-catalyzed schemes (LCSs), which play a vital role in improving the quality and total yield of STs. However, currently, the mechanism of AM remains controversial. Herein, the two mechanisms (non-catalyzed (NCM) and lipase-catalyzed (LCM)) of AM have been analyzed in detail by the density functional theory (DFT) at the molecular level. Based on the computational results, we concluded that the energy barrier of the rate-limiting step in the LCM was 18.8 kcal/mol, which is more in agreement with the available experimental value (17.8 kcal/mol), indicating that LCM could significantly accelerate the rate of AM, because it has an energy barrier ~2 times lower than that of the NCM. Interestingly, we also found that the catalytic triad (Asp-His-Ser) of the lipase and water could effectively drop the reaction barrier, which served as the general acid or base, or shuttle of the proton.

Green Synthesis of Decaglycerol Laurates by Lipase-Catalyzed Transesterification of Methyl Laurate with Decaglycerol

Decaglycerol laurates have been widely used as emulsifiers in food, medicine, and cosmetic industries for many years. Currently, they are synthesized using alkaline catalysts under stringent conditions. Here, decaglycerol laurates were prepared through a green lipase-catalyzed process, employing the transesterification of methyl laurate with decaglycerol by the immobilized lipase (Novozym 435). Single-factor experiments and orthogonal test were used for reaction optimization. The optimum conditions were obtained as follows: reaction temperature of 65°C, a laurate/decaglycerol molar ratio of 2 : 1, an oscillating speed of 180 rpm, an enzyme dosage (based on amount of methyl laurate) of 8 wt.%, initial water content (based on the total substrate mass) of 5.0 wt.%, and reaction time of 4.5 h with 84.4% conversion of methyl laurate. The transesterification products were identified by electrospray ionization mass spectrometer. In addition, the surface activity of decaglycerol laurates was also characterized, and the surface tension of water was reduced to 33 mN·m−1 at a concentration magnitude of 10−5 g/mL.

Preparation of Renewable Epoxy-Amine Resins With Tunable Thermo-Mechanical Properties, Wettability and Degradation Abilities From Lignocellulose- and Plant Oils-Derived Components.

One-hundred percent renewable triphenol—GTF—(glycerol trihydroferulate) and novel bisphenols—GDFx–(glycerol dihydroferulate) were prepared from lignocellulose-derived ferulic acid and vegetal oil components (fatty acids and glycerol) using highly selective lipase-catalyzed transesterifications. Estrogenic activity tests revealed no endocrine disruption for GDFx bisphenols. Triethyl-benzyl-ammonium chloride (TEBAC) mediated glycidylation of all bis/triphenols, afforded innocuous bio-based epoxy precursors GDFxEPO and GTF-EPO. GDFxEPO were then cured with conventional and renewable diamines, and some of them in presence of GTF-EPO. Thermo-mechanical analyses (TGA, DSC, and DMA) and degradation studies in acidic aqueous solutions of the resulting epoxy-amine resins showed excellent thermal stabilities (Td5% = 282–310°C), glass transition temperatures (Tg) ranging from 3 to 62°C, tunable tan α, and tunable degradability, respectively. It has been shown that the thermo-mechanical properties, wettability, and degradability of these epoxy-amine resins, can be finely tailored by judiciously selecting the diamine nature, the GTF-EPO content, and the fatty acid chain length.

Biodiesel Production (FAEEs) by Heterogeneous Combi-Lipase Biocatalysts Using Wet Extracted Lipids from Microalgae

The production of fatty acids ethyl esters (FAEEs) to be used as biodiesel from oleaginous microalgae shows great opportunities as an attractive source for the production of renewable fuels without competing with human food. To ensure the economic viability and environmental sustainability of the microbial biomass as a raw material, the integration of its production and transformation into the biorefinery concept is required. In the present work, lipids from wet Isochrysis galbana microalga were extracted with ethyl acetate with and without drying the microalgal biomass (dry and wet extraction method, respectively). Then, FAEEs were produced by lipase-catalyzed transesterification and esterification of the extracted lipids with ethanol using lipase B from Candida antarctica (CALB) and Pseudomonas cepacia (PC) lipase supported on SBA-15 mesoporous silica functionalized with amino groups. The conversion to FAEEs with CALB (97 and 85.5 mol% for dry and wet extraction, respectively) and PC (91 and 87 mol%) biocatalysts reached higher values than those obtained with commercial Novozym 435 (75 and 69.5 mol%). Due to the heterogeneous nature of the composition of microalgae lipids, mixtures with different CALB:PC biocatalyst ratio were used to improve conversion of wet-extracted lipids. The results showed that a 25:75 combi-lipase produced a significantly higher conversion to FAEEs (97.2 mol%) than those produced by each biocatalyst independently from wet-extracted lipids and similar ones than those obtained by each lipase from the dry extraction method. Therefore, that optimized combi-lipase biocatalyst, along with achieving the highest conversion to FAEEs, would allow improving viability of a biorefinery since biodiesel production could be performed without the energy-intensive step of biomass drying.

Reuse of immobilized lipases in the transesterification of waste fish oil for the production of biodiesel

This work deals with the optimization and enzyme reuse of lipase-catalyzed transesterification of low quality fish oil, as an environmentally friendly alternative for the biodiesel production. Three commercial immobilized enzymes, Lipozyme RM IM, Lipozyme TL IM and Novozym 435, which possess different specificity and resistance to alcohol inhibition, were employed using ethanol as acyl acceptor. For any of the lipases, the maximum yield was around 75 wt% after 8 h of reaction and 50 wt% of enzyme loading, but different ethanol to oil ratio were required. The response surface models obtained explained more than the 92% of the data, and were employed to reach optimal conditions. Maximum FAEE yield (82.91 wt%) was obtained using Novozym 435 and an excess of EtOH (1.82 g per g of oil). The reusability of the immobilized lipases was evaluated under the optimal conditions. It was found that Novozym 435 can be used for 10 consecutive cycles, with a maximum loss of activity of 16%, whereas Lipozyme RM IM and Lipozyme TL IM experienced more significant losses. An exponential model to predict and compare lipase behaviors towards several reusing cycles was proposed and validated towards the experimental data, thus simplifying the scaling up of processes.

Direct biocatalysed synthesis of first sulfur-, selenium- and tellurium- containing l-ascorbyl hybrid derivatives with radical trapping and GPx-like properties.

6-O-l-Ascorbyl selenoesters, thioesters and telluroesters can be efficiently and directly prepared from l-ascorbic acid and suitable functionalised chalcogenoesters through lipase-catalysed transesterification reactions. Novel synthesised l-ascorbyl derivatives exhibited remarkable chain breaking and glutathione peroxidase-like activities.

Dihydrogen-bonding deep eutectic solvents as reaction media for lipase-catalyzed transesterification

Choline chloride (ChCl)-based deep eutectic solvents (DESs) were successfully used as reaction media for the Candida antarctica lipase B-catalyzed transesterification. The activity of lipase in the DESs was highly influenced by the water activity of the DESs, with optimal lipase activity at a water activity of 0.1. Seventeen DESs containing one or two hydrogen bond donors (HBDs) were used for lipase-catalyzed transesterification at a selected water activity. The highest lipase activity was obtained in ChCl:urea:formamide (molar ratio of 1:1:1), whereas the highest lipase stability was achieved in ChCl:glycerol:ethylene glycol (1:1:1). In general, higher lipase activity was achieved in DESs containing amide HBDs, whereas higher lipase stability was obtained in DESs containing hydroxyl HBDs. The effects of the DESs on the activity and stability of the lipase were evaluated by determining the solvatochromic parameters. Correlation of the solvent parameters of the DESs with the lipase stability showed that the lipase stability increased with an increase in polarity based on Reichardt's dye and the hydrogen bond acidity of the DESs.

Optimization of parameters for the production of biodiesel from rubber seed oil using onsite lipase by response surface methodology.

In the present study, we demonstrate the properties of rubber seed oil (RSO) and its potential application for producing biodiesel by lipase-catalyzed transesterification. Rubber seed contains 39.45% of oil on a dry weight basis. Lipase was secreted from novel bacterial isolate of Pseudomonas aeruginosa strain BUP2. Response Surface Methodology (RSM) cum Box-Behnken Design (BBD) was employed to optimize the combined effect of different independent parameters namely oil-methanol ratio, enzyme unit, reaction temperature and reaction time. Biodiesel yield of 99.52% was obtained in the validation experiments at the optimal level of lipase (750 U), methanol ratio (1:10), temperature (45°C) and time (4h). The fuel properties of biodiesel obtained under the validation condition met the specifications as mentioned in ASTM D6751 and EN 14214 standards. Biodiesel aliquots were characterized using thin-layer chromatography (TLC), gas chromatography (GC), fourier transform infra-red spectroscopy (FTIR) and elemental analysis. The present study demonstrates an important application of a potential substitute for fossil fuel from raw feedstocks with high economic value.