Enzymatic Esterification Research Articles

Biodiesel production with enzymatic technology: progress and perspectives

AbstractRapid changes in the global climate resulting from anthropogenic activities and greenhouse gas emissions from fossil resources are encouraging commercial and academic research to seek out new routes for the production of sustainable fuels. Biodiesel, as a renewable fuel, has long been recognized as one of the solutions to meet energy demand in a climate‐constrained world. Although, several routes have been devised for biodiesel production, the enzymatic route has attracted substantial research interest. Here we discuss enzymatic esterification / transesterification technology and its contribution to the green synthesis of biodiesel. This review provides a comprehensive assessment of the fundamentals of enzymatic reaction, such as the impact of different reaction components (lipase, acyl acceptor, substrate, and reaction media) on the process parameters, along with recent developments in improving enzymatic biodiesel production, such as different lipases, combinations of lipases, and two‐step methods. Kinetics and the mechanism of enzymatic reaction when lipase is used as a catalyst are also explained in greater detail. Finally, the opportunities and challenges for the development of potentially sustainable and eco‐friendly enzymatic biodiesel technology are discussed. © 2021 Society of Industrial Chemistry and John Wiley & Sons Ltd.

A Highly Efficient Three-Liquid-Phase-Based Enzymatic One-Pot Multistep Reaction System with Recoverable Enzymes for the Synthesis of Biodiesel.

A three-liquid-phase system (TLPS) was developed and used as a novel enzymatic one-pot multistep reaction (EOMR) system. In this system, lipase and phospholipase were enriched in a single liquid phase with a high recovery (ca. 98%) and then used for the simultaneous catalysis of mutually inhibiting and interfering reactions (hydrolysis of phospholipids and glyceride in crude oil). A novel emulsion containing the two dispersed droplets (W2/O/W2 and W1/W2 emulsion structures) could be the key reason for this phenomenon because the emulsion system not only provided a new catalytic interface but also relieved the product inhibition. As a result, the content of free fatty acid (main hydrolysate of the glyceride) and the removal of phospholipid from the crude oil could be increased to 96 and 95%, respectively, within 1 h. The product obtained from the EOMR was directly used in the production of biodiesel via enzymatic esterification, and the content of fatty acid methanol ester could be increased to 93% within 2 h. Furthermore, the enzymes in the middle phase could also be reused, at least for eight rounds without significant loss in catalytic efficiency. Therefore, the TLPS could be considered as an ideal catalytic platform for the EOMR.

WITHDRAWN: Study of performance and emissions on VCR diesel engine fuelled with camphor oil and N-octanol as a nano additive

Biodiesel offers the hopeful solution as an ancillary fuel because its bio-degradability, in this investigation enzymatic trans esterification was done using lipase enzyme to produce high quality biodiesel and helps in controlling many problems. Five of samples are prepared with different Camphor oil proportions . At rated brake power conditions, the B25 & B30, followed by B10 blends emit lower level of NO X related to the diesel. At rated load, NOx emissions from B25 and B30 blends are 25% lower than diesel fuel. By analyzing the different outcomes and determining that blend provides the best solution, a conclusion was reached.

Process intensification for the autocatalytic esterification of citronellol using microwave radiation

In this study, kinetic and mechanism of autocatalytic esterification of citronellol using microwave technique was investigated. Effects of acyl donor type, reaction temperature, molar ratio of citronellol to acetic anhydride, and microwave power level on reaction conversion, yield, and selectivity were investigated. Also, autocatalytic esterification of citronellol using microwave technique was compared to those of chemical and enzymatic esterification. By increasing microwave temperature from 313 to 333 K, the reaction conversion was increased from 53.39% to 94.84%. Also, by increasing the citronellol:acetic anhydride molar ratio from 1:1.5 to 1:4.5, the reaction conversion was increased from 78.88% to 94.84%. Chemical and enzymatic catalysts had no significant effect on improving the reaction conversion when acetic anhydride was used as acyl donor. Based on the modeling studies, it can be concluded that the reaction obeys second-order kinetic model. Microwave technique decreased the activation energy by 2.46% compared to magnetic stirrer technique. In microwave technique, frequency factor and entropy were 4.55- and 1.12-folds higher than those of magnetic stirrer technique, respectively. In conclusion, autocatalytic synthesis of citronellyl acetate using microwave radiation is a simple, low-cost, and safe technique which can be propose to apply instead of conventional chemical and enzymatic methods.

PTFE-Carbon Nanotubes and Lipase B from Candida antarctica—Long-Lasting Marriage for Ultra-Fast and Fully Selective Synthesis of Levulinate Esters

An effective method for levulinic acid esters synthesis by the enzymatic Fischer esterification of levulinic acid using a lipase B from Candida antarctica (CALB) immobilized on the advanced material consisting of multi-wall carbon nanotubes (MWCNTs) and a hydrophobic polymer—polytetrafluoroethylene (Teflon, PTFE)—as a heterogeneous biocatalyst, was developed. An active phase of the biocatalyst was obtained by immobilization via interfacial activation on the surface of the hybrid material MWCNTs/PTFE (immobilization yield: 6%, activity of CALB: 5000 U∙L∙kg−1, enzyme loading: 22.5 wt.%). The catalytic activity of the obtained biocatalyst and the effects of the selected reaction parameters, including the agitation speed, the amount of PTFE in the CALB/MWCNT-PTFE biocatalyst, the amount of CALB/MWCNT-PTFE, the type of organic solvent, n-butanol excess, were tested in the esterification of levulinic acid by n-butanol. The results showed that the use of a two-fold excess of levulinic acid to n-butanol, 22.5 wt.% of CALB on MWCNT-PTFE (0.10 wt.%) and cyclohexane as a solvent at 20 °C allowed one to obtain n-butyl levulinate with a high yield (99%) and selectivity (>99%) after 45 min. The catalyst retained its activity and stability after three cycles, and then started to lose activity until dropping to a 69% yield of ester in the sixth reaction run. The presented method has opened the new possibilities for environmentally friendly synthesis of levulinate esters.

Biocatalytic Approach for Direct Esterification of Ibuprofen with Sorbitol in Biphasic Media.

Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) introduced in the 1960s and widely used as an analgesic, anti-inflammatory, and antipyretic. In its acid form, the solubility of 21 mg/L greatly limits its bioavailability. Since the bioavailability of a drug product plays a critical role in the design of oral administration dosage, this study investigated the enzymatic esterification of ibuprofen as a strategy for hydrophilization. This work proposes an enzymatic strategy for the covalent attack of highly hydrophilic molecules using acidic functions of commercially available bioactive compounds. The poorly water-soluble drug ibuprofen was esterified in a hexane/water biphasic system by direct esterification with sorbitol using the cheap biocatalyst porcine pancreas lipase (PPL), which demonstrated itself to be a suitable enzyme for the effective production of the IBU-sorbitol ester. This work reports the optimization of the esterification reaction.

Formation of taste-active pyroglutamyl peptide ethyl esters in sake by rice koji peptidases

Formation of taste-active pyroglutamyl (pGlu) peptide ethyl esters in sake was investigated: 2 enzymes (A and B) responsible for the esterification were purified from a rice koji extract. MADLI-TOF/TOF analysis after deglycosylation identified enzyme (A) as peptidase S28 (GenBank accession number OOO13707.1) and enzyme (B) as serine-type carboxypeptidase (accession number AO090010000534). Both enzymes hydrolyzed pGlu peptides and formed ethyl esters under sake mash conditions: acidic pH (3-4) and in ethanol (5%-20% v/v) aqueous solutions. Enzyme (A) formed pGlu penta-peptide ethyl esters from pGlu undeca-peptides by a prolyl endo-type reaction. Enzyme (B) formed (pGlu) deca-peptide and its ethyl esters from pGlu undeca-peptides in an exo-type reaction. We are the first to report the enzymatic ethyl esterification reaction in the formation of pGlu peptides by rice koji peptidases.

Enzymatic synthesis of bornyl linoleate in a solvent-free system

In this study, bornyl linoleate was synthesized by enzymatic esterification of borneol with linoleic acid in a solvent-free system. The influences of lipase type, reaction temperature, substrate molar ratio, lipase load and reaction time on bornyl linoleate yield were evaluated. The results indicated that the optimal conditions were as follows: 8% AYS lipase as catalyst (w/w, relative to total reactants), reaction temperature of 45 °C, molar ratio of borneol to linoleic acid of 1:2 and 12 h duration. Under the conditions, the yield of bornyl linoleate was up to 92.62%. Afterwards, the crude product was purified by molecular distillation and solvent extraction-alkali neutralization, as well, the structure of the final product was identified by mass spectrometry and nuclear magnetic resonance. The results showed that the product was confirmed to be bornyl linoleate and the purity of which was 99.02%.

Enzymatic esterification of lauric acid to give monolaurin in a microreactor

Monolaurin is a naturally occurring compound widely utilized in food and cosmetics. In this paper, we present a new method for the synthesis of monolaurin by esterification between lauric acid and glycerol catalyzed by Novozym® 435 using a microreactor. The conversion of lauric acid is 87.04% in 20 min, compared with 70.54% via the batch approach in 5 h. Using an optimized solvent system consisting of t-BuOH/ tert-amyl alcohol (1:1, v/v), the selectivity using the microreactor method is enhanced to 90.63% and the space–time yield of the process is 380.91 g/h/L. This newly devised method has the potential for application to other multiphase and enzymatic reactions.

Immobilized Lipase Based on Hollow Mesoporous Silicon Spheres for Efficient Enzymatic Synthesis of Resveratrol Ester Derivatives.

Enzymatic esterification of resveratrol is crucial for its potential application in lipophilic foods and drugs. However, the poor activity of the free enzyme hinders the reaction. In this work, the highly efficient enzymatic synthesis of resveratrol ester derivatives was achieved by immobilized lipase on hydrophobic modified hollow mesoporous silicon spheres (HMSS-C8). We preliminarily explored the use of Candida sp. 99-125 lipase (CSL) for the acylation of resveratrol, with a regioselectivity toward 3-OH- over 4'-OH-acylation. HMSS-C8 provided ideal accommodation for CSL with a loading capacity of up to 652 mg/g. The catalytic efficiency of CSL@HMSS-C8 was 15 times higher than that of free CSL, and the conversion of resveratrol reached 98.7% within only 2 h, which is the fastest value recorded in the current literature. After 10 cycles, the conversion remained up to 86.3%. Benefiting from better lipid solubility, the relative oxidation stability index values of oil containing monoester derivatives were 43.1%-68.8% and 23.9%-33.2% higher than that of refined oil and oil containing resveratrol, respectively. This research provides a new pathway for efficient enzymatic synthesis of resveratrol ester derivatives and demonstrates the potential application of resveratrol monoester derivatives as a group of excellent lipid-soluble antioxidants.

Evaluation of Consortium Enzyme towards Kojic Acid Synthesis

Consortium enzyme is a new approach in enzymatic esterification reaction to solve Kojic acid esters' low production. Combining a non-specific enzyme (Novozym 435) and a specific enzyme (Lipozyme RM IM) led to an improvement of enzymatic activity in the enzymatic routes. The findings proved that a significant percentage conversion of ester (29.2 %) was successfully achieved at the enzyme ratio (1:1) of Lipozyme RMIM and Novozym 435, the temperature at 50 ?C, amount of enzyme 0.12 g and 8 hours of reaction time. Moreover, the enzyme showed high stability against heat at 500C and can be used repeatedly up to the 5th cycle, as demonstrated by the high percentage conversion of kojic acid ester. This finding confirmed that consortium enzymes have significantly improved the reaction performance by promoting better catalytic efficiency due to the synergistic effect between combined enzymes.

Carboxylic Acid Reductase Can Catalyze Ester Synthesis in Aqueous Environments.

Most of the well-known enzymes catalyzing esterification require the minimization of water or activated substrates for activity. This work reports a new reaction catalyzed by carboxylic acid reductase (CAR), an enzyme known to transform a broad spectrum of carboxylic acids into aldehydes, with the use of ATP, Mg2+ , and NADPH as co-substrates. When NADPH was replaced by a nucleophilic alcohol, CAR from Mycobacterium marinum can catalyze esterification under aqueous conditions at room temperature. Addition of imidazole, especially at pH 10.0, significantly enhanced ester production. In comparison to other esterification enzymes such as acyltransferase and lipase, CAR gave higher esterification yields in direct esterification under aqueous conditions. The scalability of CAR catalyzed esterification was demonstrated for the synthesis of cinoxate, an active ingredient in sunscreen. The CAR esterification offers a new method for green esterification under high water content conditions.

Carboxylic Acid Reductase Can Catalyze Ester Synthesis in Aqueous Environments

AbstractMost of the well‐known enzymes catalyzing esterification require the minimization of water or activated substrates for activity. This work reports a new reaction catalyzed by carboxylic acid reductase (CAR), an enzyme known to transform a broad spectrum of carboxylic acids into aldehydes, with the use of ATP, Mg2+, and NADPH as co‐substrates. When NADPH was replaced by a nucleophilic alcohol, CAR from Mycobacterium marinum can catalyze esterification under aqueous conditions at room temperature. Addition of imidazole, especially at pH 10.0, significantly enhanced ester production. In comparison to other esterification enzymes such as acyltransferase and lipase, CAR gave higher esterification yields in direct esterification under aqueous conditions. The scalability of CAR catalyzed esterification was demonstrated for the synthesis of cinoxate, an active ingredient in sunscreen. The CAR esterification offers a new method for green esterification under high water content conditions.

Parameters Influencing Lipase-Catalyzed Glycolipid Synthesis by (Trans-)Esterification Reaction.

Glycolipids are biodegradable, non-toxic surfactants with a wide range of applications. Enzymatic esterification or transesterification facilitated in reaction media of low water activity is a reaction strategy for the production of tailor-made glycolipids as a high structural diversity can be achieved. Organic solvents, ionic liquids, and deep eutectic solvents have been applied as reaction media. However, several challenges need to be addressed for efficient (trans-)esterification reactions, especially for the lipophilization of polar substrates. Therefore, crucial parameters in (trans-)esterification reactions in conventional and non-conventional media are discussed and compared in this review with a special focus on glycolipid synthesis.

The effect of enzyme loading, alcohol/acid ratio and temperature on the enzymatic esterification of levulinic acid with methanol for methyl levulinate production: a kinetic study.

As an important bio-based chemical, methyl levulinate (ML) can be produced via enzymatic esterification of levulinic acid with methanol. A kinetic model is developed in this work based on the law of mass action and reaction reversibility, to investigate the effect of enzyme loading, alcohol/acid ratio and temperature on ML yield. Data analysis shows that newly developed binary regression is apparently more persuasive than the commonly used unitary regression. Kinetic study reveals: (1) rate constants of esterification/hydrolysis increase with increasing enzyme loading, while their ratio (equilibrium constant) remains invariant. (2) Methanol has no toxicity towards lipase, and hence, neither the rate constants of esterification/hydrolysis nor the equilibrium constant are affected by alcohol/acid ratio. (3) Both rate constants of esterification/hydrolysis and the equilibrium constant increase with temperature elevation, and their relationships agree with Arrhenius equation and Van't Hoff equation, respectively. (4) The esterification is endothermic and spontaneous. In total, the application of binary regression analysis for the developed model to study the enzymatic esterification kinetics is quite successful.

Cholesterol esterification enzymes promote cancer growth and are potential therapeutic targets for repurposed drugs: a systematic review and meta-analysis of pre-clinical evidence

Cholesterol esterification enzymes promote cancer growth and are potential therapeutic targets for repurposed drugs: a systematic review and meta-analysis of pre-clinical evidence - Volume 80 Issue OCE5

Evaluation of Consortium Enzyme towards Kojic Acid Synthesis

Consortium enzyme is a new approach in enzymatic esterification reaction to solve Kojic acid esters' low production. Combining a non-specific enzyme (Novozym 435) and a specific enzyme (Lipozyme RM IM) led to an improvement of enzymatic activity in the enzymatic routes. The findings proved that a significant percentage conversion of ester (29.2 %) was successfully achieved at the enzyme ratio (1:1) of Lipozyme RMIM and Novozym 435, the temperature at 50 ?C, amount of enzyme 0.12 g and 8 hours of reaction time. Moreover, the enzyme showed high stability against heat at 500C and can be used repeatedly up to the 5th cycle, as demonstrated by the high percentage conversion of kojic acid ester. This finding confirmed that consortium enzymes have significantly improved the reaction performance by promoting better catalytic efficiency due to the synergistic effect between combined enzymes.

Sex-specific responses in placental fatty acid oxidation, esterification and transfer capacity to maternal obesity

Fatty acid metabolism and oxidation capacity in the placenta, which likely affects the rate and composition of lipid delivered to the fetus remains poorly understood. Long chain polyunsaturated fatty acids, such as docosahexaenoic acid (DHA), are critical for fetal growth and brain development. We determined the impact of maternal obesity on placental fatty acid oxidation, esterification and transport capacity by measuring PhosphatidylCholine (PC) and LysoPhosphatidylCholine (LPC) containing DHA by mass spectrometry in mother-placenta-baby triads as well as placental free carnitine and acylcarnitine metabolites in women with normal and obese pre-pregnancy BMI. Placental protein expression of enzymes involved in beta-oxidation and esterification pathways, MFSD2a (lysophosphatidylcholine transporter) and OCTN2 (carnitine transporter) expression in syncytiotrophoblast microvillous (MVM) and basal (BM) membranes were determined by Western Blot. Maternal obesity was associated with decreased umbilical cord plasma DHA in LPC and PC fractions in male, but not female, fetuses. Basal membrane MFSD2a protein expression was increased in placenta of males of obese mothers. In female placentas, despite an increased MVM OCTN2 expression, maternal obesity was associated with a reduced MUFA-carnitine levels and increased esterification enzymes. We speculate that lower DHA-PL in fetal circulation of male offspring of obese mothers, despite a significant increase in transporter expression for LPC-DHA, may lead to low DHA needed for brain development contributing to neurological consequences that are more prevalent in male children. Female placentas likely have reduced beta-oxidation capacity and appear to store FA through greater placental esterification, suggesting impaired placenta function and lipid transfer in female placentas of obese mothers.

The Role of Water Activity in Terms of Enzyme Activity and Enantioselectivity during Enzymatic Esterification in Non-conventional Media

During enzymatic esterification in non-conventional media, the activity and enantioselectivity of the enzyme is significantly influenced by the water content of the reaction medium, which continuously changes as water is produced during the esterification. To provide constant reaction parameters, water activity should be kept constant. The commonly used salt hydrate pairs may be difficult to apply and often hinder enzyme activity. During the enantioselective esterification of racemic 2-bromopropionic acid in various solvents (organic solvents, ionic liquids), it was proven that the conditions related to the optimal water content required for kinetic examinations can be provided without using any salt or salt hydrate pairs. This conclusion is based on the realization that the optimal water activity can be set by first determining the initial water content that is necessary to achieve the maximum reaction rate in the given solvent.

Chemoenzymatic Synthesis of New Aromatic Esters of Mono- and Oligosaccharides

An efficient and convenient chemoenzymatic route for the synthesis of novel phenolic mono-, di- and oligosaccharide esters is described. Acetal derivatives of glucose, sucrose, lactose and inulin were obtained by chemical synthesis. The fully characterized pure sugar acetals were subjected to enzymatic esterification with 3-(4-hydroxyphenyl) propionic acid (HPPA) in the presence of Novozyme 435 lipase as a biocatalyst. The aromatic esters of alkyl glycosides and glucose acetal were obtained with good esterification yields, characterized by mass spectrometry (MALDI-TOF MS), infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR). The synthesis of aromatic esters of disaccharide acetals was successful only for the enzymatic esterification of sucrose acetal. The new chemoenzymatic route allowed the synthesis of novel aromatic esters of inulin as the inulin monoacetal monoester and diester and the inulin diacetal monoester with a polymerization degree of two, as well as the inulin monoacetal monoester with a degree of polymerization of three, were obtained by enzymatic acylation of inulin acetals with HPPA. These compounds could represent a new class of sugar ester surfactants with enhanced bioactivity, antioxidative and antimicrobial properties and with potential application in drug delivery systems.