Lipase-catalyzed Transesterification Research Articles

Dextran-Based Nanoparticles for Encapsulation of Ciprofloxacin

Key success for regenerative endodontics is an effective removal of bacteria inside the root canal during the treatment. Ciprofloxacin (CIP) is one of the triple antibiotics commonly used as the root canal medicament. However, the rapid clearance of antibiotics causes bacterial reinfection. Nanoparticles (NPs) provide an alternative approach for antibiotics delivery system to improve the drug stability and release control. In the previous study, modified dextran was successfully formed the ester linkage with vinyl decanoate via lipase-catalyzed transesterification. The amphiphilic dextran, dextran-decanoate (Dex-D), has been synthesized with the degree of substitution of 83-88% and were applied for CIP-loaded nanoparticles. The suitable technique for producing antibiotic carriers considering by size, shape, and drug encapsulation efficiency was investigated in this work. The preparation methods were compared between nanoprecipitation and solid-in-oil-in-water (s/o/w) ion pairing technique. We found that the obtained Dex-D nanoparticles had stable monodispersed with spherical shape in both techniques. However, Dex-D nanoparticles formed by s/o/w ion pairing technique provided smaller size with better encapsulation efficiency. The antimicrobial activity of CIP-loaded Dex-D nanoparticles against oral pathogens showed satisfactory outcome with the MIC equal to 0.7 μg/mL. Also, the compatibility of nanoparticles and dental stem cells was observed in this work.

Construction and in vitro digestibility evaluation of a novel human milk fat substitute rich in structured triglycerides

The infants who cannot be breastfeed need to obtain energy and nutrition from other sources, such as formula. In this study, a human milk fat substitute (HMFS) rich in structured triglycerides (STG) and with a variety of fatty acids was prepared by one-step transesterification reaction. The optimum conditions for the lipase-catalyzed transesterification between basa catfish oil solid fraction, Cinnamomum camphora seed kernel oil, linseed oil, microbial oil and algae oil were studied and the in vitro digestibility of the constructed HMFS was investigated. Under the optimal conditions, the obtained HMFS contained 58.86% STG and 39.73% sn-2 palmitic acid (PA). Fatty acid composition analysis showed that HMFS was composed of capric acid (Ca), lauric acid (La), oleic acid (O), linoleic acid (L), linolenic acid (Ln), arachidonic acid (ARA) and docosahexaenoic acid (DHA). LC-MS/MS analysis found that 142 new triglycerides were generated, such as Ca-P-ARA, Ca-P-Ln, La-P-ARA, La-P-L and P-O-ARA. Moreover, compared with physical mixture (PM), HMFS had better melting and crystallization temperature and the fatty acid release rate of HMFS was significantly improved. These results suggested that HMFS may have a great application in infant food as a nutritional ingredient.

Synthesis of neryl acetate by free lipase-catalyzed transesterification in organic solvents and its kinetics

Synthesis of neryl acetate by free lipase-catalyzed transesterification in organic solvents and its kinetics

Transesterification synthesis of high-yield biodiesel from black soldier fly larvae by using the combination of Lipase Eversa Transform 2.0 and Lipase SMG1

The larvae of black soldier fly (BSFL) are rich in lipids, and in the current study, BSFL was used to produce biodiesel by enzymatic transesterification with methanol. Biodiesel obtained by free lipase-catalyzed transesterification is always with side-reactions. To address the limitation of free lipase, for the first time, Lipase SMG1 and Lipase Eversa Transform 2.0 were combined to use as catalysts at the same time. The effects of different reaction conditions on the yield of biodiesel were investigated, including the type of enzyme, reaction temperature, and molar ratio of BSFL to methanol. The molar ratio of BSFL to methanol 1:3, one-step addition of methanol at 25 °C were selected as optimal conditions. The fatty acid methyl ester content achieved to 98.45% after 8h reaction under the optimal conditions. Moreover, the main properties of the final biodiesel indicators met the EN14214 biodiesel standard.

Resolution of (R,S)-1-(4-methoxyphenyl)ethanol by lipase-catalyzed stereoselective transesterification and the process optimization.

An efficient lipase-catalyzed stereoselective transesterification reaction system was established for resolution of 1-(4-methoxyphenyl)ethanol (MOPE) enantiomers. A series of lipases were tested and compared. The immobilized lipase Novozym 40086 is selected as the best choice. The effects of organic solvent, acyl donor, time and temperature on substrate conversion (c), and optical purity of the remaining substrate (eeS ) were investigated. Response surface methodology and central composite design were employed to evaluate the effect of some important factors and to optimize the process. Under the optimized conditions including solvent of n-hexane, acyl donor of vinyl acetate, temperature of 35°C, substrate molar ratio of 1:6, enzyme dosage of 20 mg, and reaction time of 2.5 h, eeS of 99.87% with c of 56.71% is achieved. The use of alkane solvent and immobilized enzyme, the mild reaction conditions, and the reduced reaction time make the system promising in industrial application.

Enzymatic modification of enriched lemon oil in a solvent-free reaction medium: Bioconversion yield and product profile

The present study focused on the modification of the chemical profile of selected terpenes and enriched lemon essential oil through lipase-catalyzed transesterification with the aim to broaden their applications. The reaction capacities of 3 terpenes (eugenol, thymol, geraniol) with vinyl esters (vinyl acetate, vinyl propionate) and commercial lipases from Candida rugosa and Candida antarctica (Novozym® 435) were studied. Phenolic terpenes were not detected to have participated in the transesterification reaction and were therefore not modified, which could be attributed to the position of the hydroxyl group on their phenyl moiety. Geraniol was successfully modified in toluene and a solvent-free medium utilizing lemon oil as the reaction medium, with bioconversion yields as high as 100% and 88%, respectively. These findings revealed the efficiency of solvent-free modification of terpene alcohols in essential oils. This method could, therefore, be considered to modify essential oils to be used as functional ingredients in food products. • Lipase from Candida rugosa and Novozym® 435 can modify geraniol with vinyl esters. • Novozym® 435 exhibited the highest acylation yields (41–100%). • Geraniol can undergo solvent-free transesterification by Novozym® 435 in lemon oil. • The solvent-free reaction reached 89% acylation yield in 15 h with vinyl esters. • Enzymatic modification of essential oils can broaden their applications.

Biocatalytic Synthesis and Characterization of Starch Ferulate Based on Ultrasonic Pretreatment of Substrate

To improve the hydrophobicity and biological activity of corn starch, starch ferulate was prepared by Novozym 435 lipase catalyzed transesterification of ultrasonic pretreated corn starch and ethyl ferulate. The ferulic acylation of starch was confirmed by UV and Fourier transform infrared spectroscopy (FT-IR). Starch ferulate was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimeter (DSC). In addition, the hygroscopicity and free radical scavenging ability of esterified starch (ES) were evaluated. In the results, the maximum degree of substitution (DS) of ES was 0.0728 under the optimal ultrasonic pretreatment conditions, which was much higher than that of 0.0142 without ultrasonic pretreatment. The XRD and DSC analysis showed that ferulic acylation destroyed the crystalline structure of corn starch to a certain extent. Moreover, ferulic acylation can improve the hydrophobicity and free radical scavenging ability of starch. In conclusion, ES obtained with ultrasonic pretreatment followed by enzyme catalysis can improve physical and chemical properties of starch. Ultrasonic provides an effective method for synthesizing high-quality modified starch and lays a theoretical foundation for expanding the application of corn starch.

Efficient Enzymatic Synthesis of Lipophilic Phenolic Glycoside Azelaic Acid Esters and Their Depigmenting Activity.

In this paper, an enzymatic route for synthesizing phenolic glycoside azelaic acid esters was successfully set up via lipase-catalyzed esterification and transesterification. Among the lipases tested, Candida antarctica lipase B (Novozyme 435) showed the highest activity in catalyzing esterification and Thermomyces lanuginosus (Lipozyme TLIM) gave the highest substrate conversion in catalyzing transesterification for the synthesis of ester. The addition of 4A molecular sieves into the reaction system is found to be an effective method for in situ absorption of the byproduct water and methanol, with which the substrate conversions of the enzymatic esterification and transesterification were 98.7 and 95.1%, respectively. Also, the main product ratios in transesterification were above 99.0% with lipozyme TLIM as a catalyst because the hydrolysis reaction was hindered. The results of the physical and biological properties indicate that all esters had higher Clog p values than their parent compounds. Also, the esters showed higher intracellular tyrosinase inhibitory and depigmentating activities than phenolic glycosides, azelaic acid (AA), and their physical mixtures due to their higher membrane penetration and tyrosinase inhibitory effects. In particular, piceid 6″-O-azelaic acid ester (PIA) showed the strongest inhibitory effect against melanin production. Its inhibitory rate was 77.4% at a concentration of 0.25 mM, about 4.2 times higher than that of arbutin (18.5%).

Integrated microsystems for lipase-catalyzed biodiesel production and glycerol removal by extraction or ultrafiltration

Competition among renewable energy sources in today's market is growing rapidly. Renewables have grown to the point where they are taking significant material market share from coal, gas, and uranium. Recently, biodiesel production has been intensified by lipase-catalyzed transesterification performed in microsystems. Another challenge in biodiesel production is the purification of the biodiesel. Common purification methods are usually more energy and time consuming than the biodiesel production itself.In this work, an integrated biodiesel production process composed of lipase-catalyzed transesterification of sunflower oil and product purification was performed in microreactor and microseparator units connected in series. Glycerol, the by-product of the transesterification process, was removed from the reaction mixture by two different separation methods, deep eutectic solvent extraction and membrane separation. Different integrated setups were developed and evaluated in terms of FAME yield and purity. The most promising integrated process was found to be the one combining 2-inlets feeding strategy for biodiesel production in a microreactor with a microseparator connected in series, in which a choline chloride-glycerol deep eutectic solvent was used. In this integrated system, a FAME yield of 94% and a glycerol content below 0.02% (w/w) were achieved for the residence time of 20 min.

Ultrasonic enhancement of lipase-catalyzed transesterification for biodiesel production from used cooking oil

Ultrasonic enhancement of lipase-catalyzed transesterification for biodiesel production from used cooking oil

Immobilized lipase-catalyzed transesterification for synthesis of biolubricant from palm oil methyl ester and trimethylolpropane.

The present study reports the effects of three commercial immobilized lipases namely Novozyme 435 from Candida antarctica lipase B (CALB), Lipozyme TL IM from Thermomyces lanuginosus and Lipozyme RM IM from Rhizomucor miehei on the production of trimethylolpropane (TMP) ester from high oleic palm methyl ester (HO-PME) and TMP. The TMP ester is a promising base oil for biolubricants that are easily biodegradable and non-toxic to humans and the environment. Enzymatic catalysts are insensitive to free fatty acid (FFA) content, hence able to mitigate the side reactions and consequently reduce product separation cost. The potential of these enzymes to produce TMP ester in a solvent-free medium was screened at various reaction time (8, 23, 30 and 48h), operating pressure (0.1, 0.3 and 1.0mbar) and enzyme dosage (1, 3, 5 and 10% w/w). The reaction was conducted at a constant temperature of 70°C and a molar ratio of 3.9:1 (HO-PME: TMP). Novozyme 435 produced the highest yield of TMP ester of 95.68 ± 3.60% under the following conditions: 23h reaction time, 0.1mbar operating pressure and 5% w/w of enzyme dosage. The key lubrication properties of the produced TMP ester are viscosity index (208 ± 2), pour point (- 30 ± - 2°C), cloud point (- 15 ± - 2°C), onset thermal degradation temperature (427.8°C), and oxidation stability, RPVOT (42 ± 4min). The properties of the TMP ester produced from the enzymatic transesterification are comparable to other vegetable oil-based biolubricants produced by chemical transesterification.

A Novel Route of Mixed Catalysis for Production of Fatty Acid Methyl Esters from Potential Seed Oil Sources

Depleting petroleum resources coupled with the environmental consequences of fossil fuel combustion have led to the search for renewable alternatives, such as biodiesel. In this study, sunflower (Helianthus annus), mustard (Brassica compestres) and pearl millet (Pennisetum americanum) seed oils were converted into biodiesel (fatty acid methyl esters) by acid-, base- and lipase-catalyzed transesterification, and the resultant fuel properties were determined. The methyl esters displayed superior iodine values (102–139), low densities, and a high cetane number (CN). The highest yield of biodiesel was obtained from mustard seed oil, which provided cloud (CP) and pour (PP) points of −3.5 and 5 °C, respectively, and a CN of 53. The sunflower seed oil methyl esters had a density of 0.81–0.86 kg/L at 16 °C, CP of 2 °C, PP of −8 °C, and a CN of 47. The pearl millet seed oil methyl esters yielded a density 0.87–0.89 kg/L, CP and PP of 4 °C and −5 °C, respectively, and a CN of 46. The major fatty acids identified in the sunflower, mustard, and pearl millet seed oils were linolenic (49.2%), oleic acid (82.2%), and linoleic acid (73.9%), respectively. The present study reports biodiesel with ideal values of CP and PP, to extend the use of biodiesel at the commercial level.

Chemoenzymatic enantioselective and stereo-convergent syntheses of lisofylline enantiomers via lipase-catalyzed kinetic resolution and optical inversion approach

• The first successful lipase-catalyzed chemoenzymatic synthesis of enantiomerically pure lisofylline has been elaborated. • Optimal biocatalytic system consisted of Candida antarctica lipase B suspended in a vinyl acetate-ethyl acetate mixture. • Stereoinversion of ( S )-lisofylline was obtained via acetolysis of ( S )-mesylate using AcOCs and hydrolysis of the acetate. • XRD analyses were performed for both lisofylline enantiomers. Highly enantioselective enzymatic kinetic resolution (EKR) of racemic lisofylline is presented for the first time. A comprehensive optimization of the key parameters of lipase-catalyzed transesterification of racemic lisofylline revealed that optimal biocatalytic system consisted of immobilized lipase type B from Candida antarctica (Chirazyme L-2, C-3) suspended in a mixture of 3 equiv of vinyl acetate as an acetyl donor and ethyl acetate as a solvent. Under optimal reaction conditions, the 1 g-scale (Chirazyme L-2, C-3)-catalyzed kinetic resolution of racemic lisofylline furnished both the EKR products in a homochiral form (>99 % ee) with the 50 % conv., and the highest possible enantioselectivity. The best results in terms of the reaction yields (47–50 %) and enantiomeric purity of the kinetically-resolved optically active products were achieved when the preparative-scale EKR was carried out for 2 h at 60 °C. In addition, stereoinversion of the less biologically-relevant ( S )-lisofylline into its ( R )-enantiomer was successfully achieved via acetolysis of the respective optically pure ( S )-mesylate by using 2 equiv of ceasium acetate and catalytic amount of 18-Crown-6 in dry toluene, followed by K 2 CO 3 -mediated methanolysis of ( R )-acetate. The elaborated EKR methodology together with enantioconvergent strategy provided a useful chemoenzymatic protocol for the synthesis of complementary enantiomers of titled API. Moreover, we report on the first single-crystal X-ray diffraction (XRD) analyses performed for the synthesized lisofylline enantiomers. Insight into the source of CAL-B stereoselectivity toward racemic lisofylline was gained by molecular docking experiments. In silico theoretical predictions matched very well with experimental results.

Lipase-catalyzed transesterification of medium-long-medium structured lipid (MLM-SL) using palm olein and tricaprylin in packed-bed reactor (PBR)

Lipase-catalyzed transesterification between refined bleached deodorized palm olein (RBDO) and tricaprylin to produce medium-long-medium structured lipid (MLM-SL) in a packed bed reactor (PBR) has been investigated. A specific sn-1,3 commercial Lipozyme TL IM was used as biocatalyst. Within this study, the progress of transesterification was monitored especially for triacylglycerol (TAG) formation with equivalent carbon number (ECN) of 32, presumably 1,3-dicapryoyl-2-oleoyl-sn-glycerol (COC). Transesterification conditions investigated were residence times (i.e., 15, 30, and 60 min) and enzyme loadings (2.0 and 4.5 g). The highest yield of ECN 32 (13%) and transesterification degree (71%) were obtained at residence time of 15 mins for both enzyme loadings. Longer residence time seemed to facilitate lipid hydrolysis over transesterification. This was indicated by the number of peaks appearing in the high-performance liquid chromatography (HPLC) chromatograms and the reduction of fat slip melting point (SMP). Additionally, the highest productivity was obtained at 2.0 g enzyme loading. Conclusively, this study has demonstrated the potential use of packed-bed reactor with immobilized Lipozyme TL IM for continuous synthesis of MLM-SLs especially TAG with ECN32.

Choline Chloride-urea Deep Eutectic Mixture Water for the Synthesis of an Amphiphilic Compound of Glyceryl Monocaffeate.

The Lipase-catalyzed synthesis of glyceryl monocaffeate (GMC) in choline chloride-urea of natural deep eutectic solvent (NADES) media is reported to provide amphiphilic character to caffeic acid (CA). The modification of CA into GMC could potentially increase its solubility and widen the application of CA's biological activities in water and oil-based systems. The high conversion was achieved when the reaction was carried out with the addition of more than 20 %v/v water, at a high molar ratio of glycerol and 40°C. It was found that the lipase-catalyzed transesterification of ethyl caffeate (EC) and glycerol in choline chloride-urea of DES media obeyed ping-pong bi-bi mechanism with Vmax = 10.9 mmol.min-1, KmEC = 126.5 mmol and KmGly = 1842.7 mmol.

Production of biodiesel from waste bio-oil through ultrasound assisted transesterification using immobilized lipase

In this study, process intensification was carried out using lipase catalyzed transesterification of waste cottonseed oil (WCSO) with ethanol in the presence of ultrasonication. A maximum conversion of 98.7% was observed for ultrasound assisted transesterification. The optimum process conditions were ethanol to oil molar ratio of 4.5:1, a reaction temperature of 45°C, enzyme loading of 5 wt%, a reaction time of 6 h, ultrasonic amplitude of 40% and the duty cycle of 15 s ON and 15 s OFF. The influence of ultrasound makes the process efficient because of an effective reduction in reaction time to 6 h with the least catalyst dosage and power consumption. Reusability tests of the catalyst were conducted after separating the immobilized Rhizopus oryzae lipase. The regenerated lipase catalyst was found to have better reusability up to the fourth cycle and the produced biodiesel was within the ASTM D6751 standard. Furthermore, the ultrasound assisted process under mild operating conditions did not affect the immobilized enzyme. It was clearly observed that ultrasonication is faster and effective for biodiesel conversion using the immobilized lipase catalyzed transesterification reactions.

Synthesis of propyl benzoate by solvent-free immobilized lipase-catalyzed transesterification: Optimization and kinetic modeling.

The present study aimed to analyze reaction kinetics and mechanism for the synthesis of propyl benzoate in solvent-free conditions. Lipase was immobilized on Hydroxypropyl methylcellulose (HPMC) and polyvinyl alcohol (PVA) polymer blend by entrapment method. Among different lipases immobilized on a support, Candida cylindracea (CCL) showed excellent activity. Systematic studies were done to optimize the reaction conditions. The activation energy was found to be 16.2kcal/mol for immobilized CCL. Kinetic parameters were calculated, which depicted that propyl benzoate synthesized using immobilized CCL followed the ternary complex model in which propanol inhibits lipase activity at higher concentrations. Recyclability of the catalyst was checked up to four catalytic cycles and 40% retention of activity was observed up to the fourth cycle. Finally, the applicability of developed protocol to synthesize various alkyl benzoates was explored.

Thermo-alkali-stable lipase from a novel Aspergillus niger: statistical optimization, enzyme purification, immobilization and its application in biodiesel production

The influences of nutritional components affecting lipase production from the new Aspergillus niger using wheat bran as substrate were studied by employing Plackett–Burman and central composite statistical designs. Out of the 11 medium components tested, sucrose, KH2PO4 and MgSO4 at final concentrations of 3.0, 1.0 and 0.5 g/L, respectively, were reported to contribute positively to enzyme production (20.09 ± 0.98 U/g ds). The enzyme was purified through ammonium sulfate precipitation followed by Sephadex G-100 gel filtration. Molecular mass of the purified lipase was 57 kDa as evident on SDS-PAGE. Different methods of immobilization were studied and the highest immobilization yield of 81.7 ± 2.18% was reported with agarose (2%) and the optimum temperature was raised from 45 to 50 °C. Immobilized lipase could retain 80% of its original activity at 60 °C after 1 hr of incubation, and was stable at pH values between neutral and alkaline pH. Lipase-catalyzed transesterification process of fungal oil resulted in a fatty acid methyl ester yield consisting of a high percentage of polyunsaturated fatty acids (83.6%), making it appropriate to be used as winter-grade biodiesel. The operational stability studies revealed that the immobilized lipase could keep 70% of its total activity after 5 cycles of the transesterification process.

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.