Enzymatic preparation of lysophosphatidylserine containing DHA from sn-glycero-3-phosphatidylserine and DHA in a solvent-free system

Green biosynthesis of DHA-phospholipids in tailor-made supersaturated DHA aqueous solution and catalytic mechanism study

Docosahexaenoic acid-phospholipids (DHA-PLs) were prepared via lipase-mediated transesterification of DHA donor and phosphatidylcholine (PC) in a purely aqueous solution. Pre-existing carriers would play the role as "artificial interfaces" to adsorb water-insoluble PC and made them disperse in water. DHA donors were concentrated by a pH-responsive method and presented as supersaturated salt solutions. 153 triacylglycerol lipase structures were analyzed and screened in silico. Transesterification was carried out to further evaluate the six lipase candidates. Lipase B from Candida antarctica (CALB) was the best biocatalyst with 34.8% of DHA incorporation and 80.0% of PLs yields (involving 38.1% PC and 41.9% sn-1 lyso-PC). Toxic organic solvents were avoided. Six possible microunits of our aqueous system consisting of three PLs donors (PC, lyso-PC, sn-glycero-3-PC) and two DHA donors (DHA and DHA salts), were simulated by molecular dynamics (MD) to illustrate the enzymatic mechanism based on diffusional channels, competitive bindings, and enzymatic structures.

Green biosynthesis of rare DHA-phospholipids by lipase-catalyzed transesterification with edible algal oil in solvent-free system and catalytic mechanism study

Docosahexaenoic acid (DHA)-enriched phosphatidylcholine (PC) has received significant scientific attention due to the health benefits in food and pharmaceutical products. In this work, the edible algal oil rich in DHA-triacylglycerol (DHA-TAG) without pretreatment was first used as the DHA donor for the transesterification of phospholipids (PLs) to prepare three kinds of rare PLs, including DHA-PC, DHA-phosphatidylethanolamine (DHA-PE), and DHA-phosphatidylserine (DHA-PS). Here, 153 protein structures of triacylglycerol lipase (EC 3.1.1.3) were virtually screened and evaluated by transesterification. PLA1 was the best candidate due to a higher DHA incorporation. Results showed that the transesterification of PC with DHA-TAG at 45°C and 0.7% water content (without additional water addition) could produce DHA-PC with 39.1% DHA incorporation at 30 min. The different DHA donors, including forms of fatty acid, methyl ester, and triglycerides, were compared. Molecular dynamics (MD) was used to illustrate the catalytic mechanism at the molecular level containing the diffusions of substrates, the structure-activity relationship of PLA1, and the effect of water content.

The efficient and green synthesis of biodiesel from crude oil without degumming catalyzed by sodium carbonate supported MoS2

The transesterification of lecithin with methanol catalyzed by 23 kinds of alkaline salts was investigated for the preparation of biodiesel. Sodium carbonate was confirmed as the best catalyst due to its excellent catalytic performance, environmental friendliness, and great stability. Next, it was successfully immobilized on the surface of hierarchical nanosheets of MoS₂. The prepared catalyst was characterized via XRD, FTIR, SEM, and TEM techniques. After immobilization, the highest specific activity reached 40.58 ± 0.78 U mg_Na2CO3⁻¹, which was 2.43 times higher than that of unsupported Na₂CO₃. Meanwhile, the highest yield reached 99.8%. The excellent performance of the supported catalysts was attributed to a synergistic effect between MoS₂ and the absorbed sodium carbonate. Firstly, sodium carbonate was uniformly dispersed on the surface of MoS₂ to minimize the mass transfer resistance. Secondly, the electron-rich outer layer of MoS₂ promoted the deprotonation of methanol to form methoxy anions. The prepared catalyst was further applied in the transesterification of lecithin-containing triglycerides to prepare fatty acid methyl esters (FAMEs). The experimental results showed that the addition of lecithin would promote the transesterification of triglycerides. The yields of FAMEs were close to 100% in all cases when the lecithin content was increased from 1% to 40%. Hence, this supported sodium carbonate catalyst should be a promising candidate for biodiesel production from crude oil without degumming.

The transesterification of lecithin with methanol catalyzed by sodium carbonate supported MoS₂ was investigated for the preparation of biodiesel.