Enzymatic synthesis of low-calorie structured lipids in a solvent-free system

For the synthesis of low-calorie structured lipids (LCSL), transesterification between triacetin and stearic acid using immobilized lipase in a solvent-free system was investigated. Stearic acid, a long-chain saturated fatty acid, was incorporated mainly into the sn-1 and/or sn-3 positions of triacetin by lipase-catalyzed reaction. Three types of reactor systems (open, closed, and vacuum) were studied for the production of LCSL. The effects of various reaction variables such as water activity of substrates and lipase, molar ratio of substrates, stirring speed and reaction temperature were investigated. In the vacuum reactor system, a certain amount of water was added periodically to maintain the optimal water content of the reaction system. When a suitable amount of water (0.65 wt% of substrates) was added at every 1 h into the vacuum reactor system, more than 88% LCSL was obtained within 4 h using Chirazyme^® L-2.     

Chemo-enzymatic synthesis and sustained release of optically active polymeric prodrugs of chlorphenesin

Optically active polymeric prodrugs containing saccharides were prepared via a facile procedure combining enzymatic resolution with chemical polymerization. Polymerizable optically active chlorphenesin derivatives were obtained in excellent optically purity (ee > 99.9%) and high yield (∼50%) in short time (∼4 h) by lipase-catalyzed resolution after optimization of reaction conditions. Then, polymerizable optically active monomer was copolymerized with different polymerizable glycolipids using free radical polymerization method. The obtained optically active polymeric prodrugs bearing (R)-chlorphenesin residue were characterized by IR, NMR and GPC. In vitro released studies showed that the cumulative released optically pure chlorphenesin (ee = 88-92%) from the polymeric prodrug (VADG) was from 19.3% to 34.3% in pH 7.4, pH 5.4 and pH 1.2 after 7 days. The cumulative liberation rate of optically active polymeric prodrugs (ee = ∼88%) with different glycolipids was from 26.4% to 38.5% in pH 1.2.     

Radical Scavenging Activity of Lipophilized Products from Lipase-Catalyzed Transesterification of Triolein with Cinnamic and Ferulic Acids

Lipase-catalyzed transesterification of triolein with cinnamic and ferulic acids using an immobilized lipase from Candida antarctica (E.C. 3.1.1.3) was conducted to evaluate the antioxidant activity of the lipophilized products as model systems for enhanced protection of unsaturated oil. The lipophilized products were identified using ESI-MS. Free radical scavenging activity was determined using the DPPH radical method. The polarity of the solvents proved important in determining the radical scavenging activity of the substrates. Ferulic acid showed much higher radical scavenging activity than cinnamic acid, which has limited activity. The esterification of cinnamic acid and ferulic acid with triolein resulted in significant increase and decrease in the radical scavenging activity, respectively. These opposite effects were due to the effect of addition of electron-donating alkyl groups on the predominant mechanism of reaction (hydrogen atom transfer or electron transfer) of a species with DPPH. The effect of esterification of cinnamic acid was confirmed using ethyl cinnamate which greatly enhances the radical scavenging activity. Although, compared to the lipophilized cinnamic acid product, the activity was lower. The radical scavenging activity of the main component isolated from lipophilized cinnamic acid product using solid phase extraction, monocinnamoyl dioleoyl glycerol, was as good as the unseparated mixture of lipophilized product. Based on the ratio of a substrate to DPPH concentration, lipophilized ferulic acid was a much more efficient radical scavenger than lipophilized cinnamic acid.     

Optimization of Selective Lipase-Catalyzed Feruloylated Monoacylglycerols by Response Surface Methodology

The use of solvent engineering to achieve selective enzymatic synthesis of feruloylated acylglycerols during the transesterification of ethyl ferulate with TAG was investigated. Novozym 435 catalyzed transesterification of ethyl ferulate and TAG resulted in a mixture of feruloylated monoacylglycerols (FMAG) and feruloylated diacylglycerols (FDAG). These feruloylated acylglycerols have recently received much attention because of their health benefits, antioxidant properties and UV absorption. However, FMAG in a pure form is more advantageous than the FMAG–FDAG mixture in exhibiting stabilizing, emulsifying and conditioning properties. Thus, it is significant to perform efficient selectivity in the synthetic process. In this present study, the effect of various solvent mixtures, including unitary, binary and ternary organic media selective enzymatic synthesis of feruloylated acylglycerols was investigated by response surface methodology. Selectivity towards FMAG substantially increased from 14.5% in the unitary solvent n-hexane to 94.2% in the binary mixtures of 2-methyl-2-butanol (2M2B) and toluene (1:1, v/v). The maximum conversion achieved was 75.4% in this binary mixture medium. Analysis of variance (ANOVA) showed that 99.6% of the observed variation was explained by the polynomial model. Lack of fit analysis indicated that the regress equation was adequate for predicting the degree of the selectivity.     

Two-Step Production of Oil Enriched in Conjugated Linoleic Acids and Diacylglycerol

A two-step process was used to produce diacylglycerol-enriched structured lipid that contained mainly c9,t11 and t10,c12 isomers of conjugated linoleic acids (CLA). First, a structured triacylglycerol (TAG) was synthesized by lipase-catalyzed acidolysis of corn oil with CLA. This structured triacylglycerol contained 30.4 mol% CLA with 45.5% of the CLA mostly located at sn-1,3 positions of the glycerol backbone. Then, lipase-catalyzed glycerolysis was conducted between structured triacylglycerol and glycerol to produce diacylglycerol-enriched structured lipid. The final product contained 6.8% monoacylglycerol, 31.5% diacylglycerol and 61.1% TAG after 48 h reaction. The selected chemical (fatty acid composition, the content of mono-, di-, and triacylglycerol in the reaction product) and physical properties (melting profile) were determined by hihg-performance liquid chromatography (HPLC), gas chromatography (GC), and differential scanning calorimetry (DSC).     

Lipase-catalyzed synthesis and characterization of copolymers from ethyl acrylate as the only monomer starting material

Several acrylic copolymers containing, at random, sequences of poly(ethyl acrylate) and poly(N-(2-hydroxyethyl)acrylamide) were obtained from ethyl acrylate as the only monomer starting material in a chain polymerization process, catalyzed by Candida antarctica lipase B. In the presence of ethanolamine, the enzyme not only catalyzes the chain polymerization of ethyl acrylate but also aminolysis the pendant ester groups. The products, characterized by FTIR, ¹H and ¹³C NMR and UV-MALDI-TOF-MS, show low molecular weight and high monodispersity. The activity showed by C. antarctica lipase B in the polymerization reaction is a new example of enzyme promiscuity.     

Lipase-catalyzed synthesis and characterization of a novel linear polyamidoamine oligomer

A linear polyamidoamine oligomer was obtained by polymerization of ethyl acrylate and N-methyl-1,3-diaminopropane, catalyzed by the Candida antarctica lipase. Depending on the reaction conditions such as substrates concentration, solvent and enzyme:substrate ratio, the enzyme catalyzes the polymerization reaction or Michael adducts formation. The polymeric material, characterized by FTIR, ¹H and ¹³C NMR and UV-MALDI-TOF-MS, shows low molecular weight and high monodispersity. The activity showed by C. antarctica lipase in the polymerization reaction is highly selective and allows to obtain a product with potential biomedical applications in mild condition reactions and low environmental impact.     

Lipase-Catalyzed Synthesis of Sn-2 Palmitate: A Review

Human milk fat (HMF) is an important source of nutrients and energy for infants. Triacylglycerols (TAGs) account for about 98% of HMF and have a unique molecular structure. HMF is highly enriched in palmitic acid (PA) at the sn-2 position of the glycerol backbone (more than 70%) and in unsaturated fatty acids at the sn-1,3 position. The specific TAG structure in HMF plays a valuable function in infant growth. Sn-2 palmitate (mainly 1,3-dioleoyl-2-palmitoyl-glycerol) is one of the structured TAGs that is commonly supplemented into infant formula in order to enable it to present a similar structure to HMF. In this review, the development of the lipase-catalyzed synthesis of sn-2 palmitate over the last 25 years are summarized, with a focus on reaction schemes in a laboratory setting. Particular attention is also paid to the commercialized sn-1,3 regioselective lipases that are used in structured TAGs synthesis, to general methods of TAG analysis, and to successfully developed sn-2 palmitate products on the market. Prospects for the lipase-catalyzed synthesis of sn-2 palmitate are discussed.     

非水相脂肪酶催化体系分子筛脱水机制的研究

研究了非水相脂肪酶催化体系中分子筛的脱水机制.用Karl Fisher方法测定有机溶剂中的水分含量,研究在乙腈、2-甲基-2-丙醇、2-甲基-2-丁醇三种有机溶剂中分子筛的吸水等温线;着重探讨了以乙腈作溶剂时,甘露糖、蔗糖、月桂酸等底物共存对分子筛吸水行为的影响.为非水相脂肪酶催化体系建立理论预测产物平衡转化率的数学模型提供了必要的参数.     

Interpretation of triacylglycerol profiles of palm oil,palm kernel oil and their binary blends

The effects of lipase-catalyzed interesterification (IE) on changes in the chemical composition of palm oil (PO), palm kernel oil (PKO) and their binary blends at 3:1, 1:1 and 1:3 (w/w) ratios, using both 1,3 specific Rhizomucor miehei, (Lipozyme™) and non-specific Pseudomonas sp. lipases were evaluated. IE of the native PO and PKO showed very distinct chemical composition changes. Catalysis of PO, using both lipases, caused synthesis of more medium and long chain triacylglycerols (TAG), with MMM/OLL, MMP, OOO and PPP (M, myristic acid; O, oleic acid; L, linoleic acid; P, palmitic acid) increasing in concentration. In contrast, IE of PKO resulted in the formation of more short and medium chain TAG, with LaLaO and LaMO (La, lauric acid; C, capric acid) experiencing noteworthy increments. Both Rhizomucor miehei and Pseudomonas sp. lipases showed high affinity in hydrolyzing PO fatty acids, resulting in high TAG losses and formation of high percentages of partial glycerides while these lipases were found to enhance the synthesis process in IE of PKO. Catalysis of the three binary blends caused similar TAG compositional changes where the synthesis process focussed on the medium chain TAG, while hydrolysis was observed in the short and long chain TAG that showed corresponding decreases. Catalysis of the three blends was influenced by the major fraction of these blends. Among these blends, PO: PKO at a 1:1 ratio exhibited the highest degree of IE. The diversity and quantity of available TAG are postulated to be the main causes of the different catalytic activities in these binary blends with Pseudomonas sp. lipase showing a higher degree and rate of IE than R. miehei.