Emulsifying Properties of Lecithin Containing Different Fatty Acids Obtained by Immobilized Lecitase Ultra-Catalyzed Reaction

Progress & Prospect of Enzyme-Mediated Structured Phospholipids Preparation

In recent years, structured phospholipids (SPLs), which are modified phospholipids (PLs), have attracted more attention due to their great potential for application in the field of pharmacy, food, cosmetics, and health. SPLs not only possess enhanced chemical, physical and nutritional properties, but also present superior bioavailability in comparison with other lipid forms, such as triacylglycerols, which make SPLs become more competitive carriers to increase the absorption of the specific fatty acids in the body. Compared with chemical-mediated SPLs, the process of enzyme-mediated SPLs has the advantages of high product variety, high substrate selectivity, and mild operation conditions. Both lipases and phospholipases can be used in the enzymatic production of SPLs, and the main reaction type contains esterification, acidolysis, and transesterification. During the preparation, reaction medium, acyl migration, water content/activity, substrates and enzymes, and some other parameters have significant effects on the production and purity of the desired PLs products. In this paper, the progress in enzymatic modification of PLs over the last 20 years is reviewed. Reaction types and characteristic parameters are summarized in detail and the parameters affecting acyl migration are first discussed to give the inspiration to optimize the enzyme-mediated SPLs preparation. To expand the application of enzyme-mediated SPLs in the future, the prospect of further study on SPLs is also proposed at the end of the paper.

Characteristics and emulsifying properties of structured phospholipids from palm pressed fiber and omega-3 fatty acid concentrates from by-products of fish processing by enzymatic acidolysis

The synthesis of structured phospholipids (SPLs) containing ω-3 fatty acids was carried out through enzymatic acidolysis reactions using lipase from Rhizomucor miehei between palm pressed fiber phospholipids (PPF PL) with four ω-3 fatty acid concentrates as different acyl sources. The purity of SPLs increased compared to original PPF PLs. The degree of ω-3 fatty acid incorporation to the SPLs was different that depended on the sources of acyl. The highest degree of incorporation was in PE (phosphatidylethanolamine). The phenomenon of acyl migration of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) was found from the sn-1 to the sn-2 position of the PE. This acyl migration occurred at all four SPLs. Modification of PLs made better emulsifying properties for oil in water emulsion system, compared to PPF PL. The increase in the HLB (hydrophilic-lipophilic balance) value, EAI (emulsifying activity index), and ESI (emulsion stability index) of SPLs compared to PPF PL was supposed to relate to an increase in polarity. The composition of more polar PLs (PC/phosphatidylcholine, PE, PG/phosphatidylglycerol, and PA/phosphatidic acid) in the four SPLs is higher than that of PPF PL. The sources of acyl also affected the emulsifying properties of four SPLs.

Correlations of Fat Content in Human Milk with Fat Droplet Size and Phospholipid Species

Fat globule size and phospholipid (PL) content in human milk (HM) were investigated. HM was classified into three groups depending on fat content (A < B < C). PL content (mg/100 g HM) was significantly higher in the C group (p < 0.05), indicating its positive relationship with HM fat content. When the PL content was normalized (mg/g fat), that of group A was significantly higher (p < 0.05) and fat droplet size in group C was slightly larger, suggesting that HM fat content is affected by fat droplet numbers to a larger extent than by fat droplet size. A correlation between PC and SM content in HM was observed regardless of fat content, while correlation between PE and either PC or SM increased in the order of C > B > A, hence the composition and content of PL species in HM varied according to its fat content.

Immobilized Phospholipase A1-Catalyzed Preparation of l-α-Glycerylphosphorylcholine from Phosphatidylcholine

This study sought to prepare a cognitive enhancer l-α-glycerylphosphorylcholine (l-α-GPC) using an immobilized Lecitase Ultra (LU, phospholipase A₁) to catalyze the hydrolysis of soy phosphatidylcholine (PC). Immobilization of LU on Lewatit VP OC 1600 provided the highest fixation level (83.1 g/100 g) and greatest catalytic activity achieving 100 g/100 g l-α-GPC within 20 h and was therefore selected as the optimal system for biocatalysis. Immobilization of LU increased its positional specificity compared to free LU, as shown by a decrease in the production of the phosphocholine byproduct. Under the optimal conditions determined by response surface methodology, PC was completely hydrolyzed to l-α-GPC and required a simple purification via phase separation of the biphasic media to obtain a yield of ∼26.4 g l-α-GPC from 100 g PC, with a purity of 98.5 g/100 g. Our findings suggest a possibility of using the immobilized LU as a new biocatalyst for the l-α-GPC production.

Enantioselective Transesterification of Allyl Alcohols with (E)-4-Arylbut-3-en-2-ol Motif by Immobilized Lecitase™ Ultra

Lecitase™ Ultra was immobilized on four different supports and tested for the first time as the biocatalyst in the kinetic resolution of racemic allyl alcohols with the (E)-4-arylbut-3-en-2-ol system in the process of transesterification. The most effective biocatalyst turned out to be the enzyme immobilized on agarose activated with cyanogen bromide (LU-CNBr). The best results (E > 200, ees and eep = 95–99%) were obtained for (E)-4-phenylbut-3-en-2-ol and its analog with a 2,5-dimethylphenyl ring whereas the lowest ee of kinetic resolution products (90%) was achieved for the substrate with a 4-methoxyphenyl substituent. For all substrates, (R)-enantiomers were esterified faster than their (S)-antipodes. The results showed that LU-CNBr is a versatile biocatalyst, showing high activity and enantioselectivity in a wide range of organic solvents in the presence of commonly used acyl donors. High operational stability of LU-CNBr allows it to be reused in three subsequent reaction cycles without negative effects on the efficiency and enantioselectivity of transesterification. This biocatalyst can become attractive to the commercial lipases in the process of the kinetic resolution of allyl alcohols.

Free and Immobilized Lecitase™ Ultra as the Biocatalyst in the Kinetic Resolution of (E)-4-Arylbut-3-en-2-yl Esters

The influence of buffer type, co-solvent type, and acyl chain length was investigated for the enantioselective hydrolysis of racemic 4-arylbut-3-en-2-yl esters using Lecitase™ Ultra (LU). Immobilized preparations of the Lecitase™ Ultra enzyme had significantly higher activity and enantioselectivity than the free enzyme, particularly for 4-phenylbut-3-en-2-yl butyrate as the substrate. Moreover, the kinetic resolution with the immobilized enzyme was achieved in a much shorter time (24–48 h). Lecitase™ Ultra, immobilized on cyanogen bromide-activated agarose, was particularly effective, producing, after 24 h of reaction time in phosphate buffer (pH 7.2) with acetone as co-solvent, both (R)-alcohols and unreacted (S)-esters with good to excellent enantiomeric excesses (ee 90–99%). These conditions and enzyme were also suitable for the kinetic separation of racemic (E)-4-phenylbut-3-en-2-yl butyrate analogs containing methyl substituents on the benzene ring (4b,4c), but they did not show any enantioselectivity toward (E)-4-(4’-methoxyphenyl)but-3-en-2-yl butyrate (4d).

Lipopolysaccharide Polyelectrolyte Complex for Oral Delivery of an Anti-tubercular Drug

Anti-tuberculosis drug delivery has remained a challenge due to inconsistent bioavailability and inadequate sustained-release properties leading to treatment failure. To resolve these drawbacks, a lipopolysaccharide polyelectrolyte complex (PEC) encapsulated with rifampicin (RIF) (as the model drug) was fabricated, using the solvent injection technique (SIT), with soy lecithin (SLCT), and low-molecular-weight chitosan (LWCT). The average particle size and surface charge of RIF-loaded PEC particulates was 151.6 nm and + 33.0 nm, respectively, with noted decreased particle size and surface charge following increase in SLCT-LWCT mass ratio. Encapsulation efficiency (%EE) and drug-loading capacity (%LC) was 64.25% and 5.84%, respectively. Increase in SLCT-LWCT mass ratio significantly increased %EE with a marginal reduction in %LC. In vitro release studies showed a sustained-release profile for the PEC particulate tablet over 24 h (11.4% cumulative release) where the dominant release mechanism involved non-Fickian anomalous transport shifting towards super case II release as SLCT ratios increased (6.4% cumulative release). PEC-tablets prepared without SIT presented with rapid Fickian-diffusion-based drug release with up to 90% RIF release within 4 h. Ex vivo permeability studies revealed that lipopolysaccharide PEComplexation significantly increased the permeability of RIF by ~ 2-fold within the 8-h study period. These results suggest successful encapsulation of RIF within a PEC structure while imparting increased amorphic regions, as indicated by x-ray diffraction, for potential benefits in improved drug dissolution, bioavailability, and dosing.

Application of Lecitase® Ultra-Catalyzed Hydrolysis to the Kinetic Resolution of (E)-4-phenylbut-3-en-2-yl Esters

The possibility of using Lecitase® Ultra as a novel alternative biocatalyst for the kinetic resolution of model racemic allyl esters of (E)-4-phenylbut-3-en-3-ol: Acetate (4a) and propionate (4b) through their enantioselective hydrolysis was investigated. Reaction afforded (+)-(R)-alcohol (3) and unreacted (−)-(S)-ester (4a or 4b). Hydrolysis of propionate 4b proceeded with higher enantioselectivity than acetate 4a. (R)-Alcohol (3) with highest enantiomeric excess (93–99%) was obtained at 20–30 °C by hydrolysis of propionate 4b, while the highest optical purity of unreacted substrate was observed for (S)-acetate 4a (ee = 34–56%). The highest enantioselectivity was found for the hydrolysis of propionate 4b catalyzed at 30 °C (E = 38). Reaction carried out at 40 °C significantly lowered enantiomeric excess of produced alcohol 3 and enantioselectivity in resolution. Lecitase® Ultra catalyzed the enantioselective hydrolysis of allyl esters 4a,b according to Kazlauskas’ rule to produce (R)-alcohol 3 and can find application as a novel biocatalyst in the processes of kinetic resolution of racemic allyl esters.

Production of Structured Phosphatidylcholine with High Content of Myristic Acid by Lipase-Catalyzed Acidolysis and Interesterification

Synthesis of structured phosphatidylcholine (PC) enriched with myristic acid (MA) was conducted by acidolysis and interesterification reactions using immobilized lipases as catalysts and two acyl donors: trimyristin (TMA) isolated from ground nutmeg, and myristic acid obtained by saponification of TMA. Screening experiments indicated that the most effective biocatalyst for interesterification was Rhizomucor miehei lipase (RML), whereas for acidolysis, the most active were Thermomyces lanuginosus lipase (TLL) and RML. The effect of the molar ratio of substrates (egg-yolk PC/acyl donor), enzyme loading, and different solvent on the incorporation of MA into PC and on PC recovery was studied. The maximal incorporation of MA (44 wt%) was achieved after 48 h of RML-catalyzed interesterification in hexane using substrates molar ratio (PC/trimyristin) 1/5 and 30% enzyme load. Comparable results were obtained in toluene with 1/3 substrates molar ratio. Interesterification of PC with trimyristin resulted in significantly higher MA incorporation than acidolysis with myristic acid, particularly in the reactions catalyzed by RML.

Effect of temperature, water content and free fatty acid on reverse micelle formation of phospholipids in vegetable oil

The self-assembly of phospholipids in oil, specifically lecithin in rapeseed oil, was investigated by combining experimental and computational methods The influence of temperature, water, and free fatty acids on the onset of lecithin aggregation in the rapeseed oil was determined using the 7,7,8,8 -tetracyanoquinodimethane dye (TCNQ) solubilization method and the size and shape of the self-assembled lecithin structures were investigated by small-angle X-ray scattering and cryogenic transmission electron microscopy. In the absence of excess water in the system (0.03wt-% water in oil), stable cylindrical lecithin reverse micelles were observed above the critical micelle concentration (CMC). Comparing the aggregation response in room temperature and at 70°C revealed that CMC decreased with increasing temperature. Furthermore, already a modest amount of added water (0.3wt-% water in oil) was sufficient to induce the formation of lamellar lecithin structures, that phase separated from the oil. In low water content, oleic acid suppressed the formation of lecithin reverse micelles whereas in the presence of more water, the oleic acid stabilized the reverse micelles. Consequently, more water was needed to induce phase separation in the presence of oleic acid. Molecular dynamics simulations indicated that the stabilizing effect of oleic acid resulted from oleic acid enhancing phospholipid solubilization in the oil by forming a solvating shell around the phosphate head group. The findings showed that the response of the mixed surfactant system is a delicate interplay of the different components and variables. The significance of the observations is that multiple parameters need to be controlled for desired system response, for example towards vegetable oil purification or phospholipid based microemulsions.