Synthesis of (+)-goniothalamin and its enantiomer by combination of lipase catalyzed resolution and alkene metathesis

(+)-Goniothalamin has been synthesized by lipase catalyzed resolution of (1E)-1-phenylhexa-1,5-dien-3-ol using vinyl acrylate as acyl donor followed by ring closing metathesis of the formed (1R)-1-[(E)-2-phenylvinyl]but-3-enyl acrylate. The unreacted alcohol from the resolution, (1E,3S)-1-phenylhexa-1,5-dien-3-ol, was esterified non-enzymatically, and used for synthesis of (−)-goniothalamin.     

Reaction kinetics of the esterification of lauric acid in iso-octane using an immobilized biocatalyst

The kinetics of the esterification of lauric acid with geraniol catalyzed by a commercially immobilized lipase preparation fromMucor miehei, Lipozyme, was studied in well-stirred flasks under conditions of no external mass transfer limitations. It was shown that the reaction is inhibited by lauric acid and the reaction mechanism can be described as a Ping-Pong Bi-Bi with Dead-End inhibition caused by lauric acid.     

固定化脂肪酶催化合成6,6'-海藻糖月桂酸酯

 以吸附在硅藻土上的假丝酵母（Candidasp．1619）脂肪酶为催\r\n化剂，在无溶剂体系中，研究了月桂酸与海藻糖的酯化反应．结果表明\r\n，反应温度为47℃，pH为7．0，月桂酸与海藻糖的摩尔比大于6时酯化\r\n反应的转化率较高．在3．2mmol（0．64g）月桂酸、0．2mmol（0．07\r\n6g，即53μl浓度为1．43g／ml的糖溶液）海藻糖和200mg固定化脂肪酶\r\n（1000U）组成的反应体系中，于47℃振荡反应36h，以海藻糖月桂酸双\r\n酯计算，酯化程度达95％以上．用有机溶剂提取的反应产物经薄层色谱\r\n提纯后进行13CNMR分析，结果表明，产物主要是6，6’－海藻糖月桂酸\r\n酯，其纯度为90％～95％．     

Influence of the support on the reaction course of tributyrin hydrolysis catalyzed by soluble and immobilized lipases

Lipases from different origins have been immobilized in supports chosen by its different aquaphilicity and used as biocatalysts for the hydrolysis of tributyrin. The changes of the concentration of tri-, di-, monobutyrin, glycerol, and butyric acid during the reactions catalyzed by soluble, as well as immobilized, lipases were evaluated by gas chromatography. The experimental data were fitted to a simple kinetic model for the sequential reaction of tributyrin hydrolysis. The calculated apparent rate constants were different for the biocatalysts used and were apparently related to diffusional effects and aquaphilicity of the supports. Maximal yields of dibutyrin were found with the soluble Candida lipase, whereas the highest yield of monobutyrin (90%) was obtained with the least aquaphylic derivative (Candida-Celite).     

Microwave-assisted solvent-free lipase catalyzed transesterification of β-ketoesters

Abstract

Lipase-catalyzed transesterification was used as an efficient tool for the interconversion of β-ketoesters. Catalytic activity of commercial lipase B from Candida antarctica (Novozym 435) was evaluated in systems involving non activated acyl donors, and enhanced using microwave irradiation. Interestingly, the combination of CAL B in microwave irradiation worked excellent in solvent-free conditions, thus assuring a highly competitive and environment-friendly process with high yields (up to 96%) in competitive times (< 2h). The combination of biocatalysis with solvent-free systems and microwave assistance is currently scarcely used, and may represent a powerful synergy for preparative reactions.     

亲水梳状环氧聚合物载体柔性固定化脂肪酶

以氯乙酰化聚苯乙烯微球载体为大分子引发剂,以甲基丙烯酸缩水甘油酯和亲水性丙烯酰胺为共聚接枝单体,以氯化亚铜及2,2'-联吡啶为催化体系,采用原子转移自由基聚合法接枝合成了具有柔性链的亲水梳状环氧聚合物载体PS-acyl-P(AM-co-GMA),并将其用于耐有机溶剂YCJ01脂肪酶的共价柔性固定化.结果表明,固定化酶催...     

A lipase catalyzed condensation reaction with a tricyclic diketone: yet another example of biocatalytic promiscuity

Novozym 435 (a commercially available immobilized form of Candida antarctica lipase B) was found to catalyze a condensation reaction of 5-hydroxy-endo-tricyclo[5.2.1.0^2,6]deca-4,8-dien-3-one with acetaldehyde (enzymatically produced from vinyl acetate in situ) under low water conditions, in presence of 10% organic co-solvent (N,N-dimethyl formamide or pyridine), to form a bis-adduct. Even though the condensation reaction occurred with pyridine (acting as a base catalyst) in the presence of acetaldehyde and in the absence of enzyme, the reaction was very slow as compared to the enzymatic process. Thus, while the non-enzymatic process took 4 days to achieve 100% conversion; in presence of enzyme it was possible within 4 h.     

Study of pancreatic lipase inhibition kinetics and LC–QTOF–MS‐based identification of bioactive constituents of Momordica charantia fruits

The different parts of Momordica charantia have been reported to have several therapeutic applications against hyperglycemia and hypercholesterolemia associated with pancreatic lipase (PL). Inhibition of this enzyme prevents the absorption of dietary triglyceride in the intestine, and thus exerts an anti‐obesity effect. This study aimed to investigate the bioactive constituents of the fruits of M. charantia (MCF) extract and fractions against pancreatic PL followed by study of their inhibition kinetics. The PL inhibitory assay was performed spectrophotometrically by measuring the change in absorbance of the products at 405 nm, using p‐nitrophenylcaprylate as substrate. The results indicated that the ethyl acetate fraction of MCF (EFMC) offered significant, dose‐dependent inhibition against PL, compared with the positive control, Orlistat. The enzyme kinetics study revealed the inhibition to be a mixed type in nature. Additionally, the total phenol and flavonoid content of the fractions was estimated. A positive correlation between phenolic content of EFMC and its PL inhibitory activity was established statistically, which implied that higher inhibition potential was contributed by the phenolic compounds. The identification of the bioactive constituents was further confirmed by LC–QTOF–MS study. This finding suggested that phenolic compounds of MCF can serve as functional food components to address obesity‐related disorders linked with PL.