Synthesis of sucrose 6-acetate by immobilized aspergillus Niger lipase imprinted with oleic acid and sorbitol.

Biological and interfacial imprinting both were effective methods to improve the catalytic performance of lipase in organic solvent. Bioimprinting combined with interfacial activation of lipase was investigated for obtaining imprinted lipase with excellent catalytic performance. Enzymatic synthesis of sucrose-6-acetate in organic solvents to test the performance of imprinted lipase immobilized by adsorbing on macroporous resin.

Biocatalytic synthesis of L-ascorbyl palmitate using oleic acid imprinted Aspergillus niger lipase immobilized on resin.

In order to improve the esterification efficiency of the enzymatic synthesis of l-ascorbic acid palmitate, the substrate analogue imprinting of the Aspergillus niger lipase-catalyzed esterification process was studied. Oleic acid was selected as the imprinting molecule, oleic acid imprinting immobilized lipase was prepared at pH 8.0, 0.

Detection of Tyrosinase Activity and Inhibitor Validation Based on N-GQDs Fluorescence Sensor.

Tyrosinase inhibitors have the ability to resist melanin formation and can be used for clinical and cosmetic, so it is becoming extremely crucial to search a rapid and effective method for detecting t the activity of tyrosinase. In this study, a sensing probe based on Nitrogen-doped graphene quantum dots (N-GQDs) were prepared with carbamide and citric acid. Tyrosinase can oxidize dopamine to dopamine quinone, which can quench the fluorescence of N-GQDs based on the principle of fluorescence resonance energy transfer (FRET) process, and then the detection of tyrosinase activity can be achieved.

Magnetic nanoparticles immobilized thrombin ligand fishing to screen thrombin inhibitors in natural products.

In this study, thrombin was immobilized with magnetic particles modified by glutaraldehyde. The changes in secondary structures of immobilized enzyme revealed an increment in conformational rigidity and stability, which can be reflected in temperature and pH stability as well as the tolerance of organic reagents. The optimal reutilization times of magnetic particle immobilized thrombin were 7 times, and the half-life of enzyme activity preserved at room temperature was 5 days, which was 2.

The correlation of molecule weight of chitosan oligomers with the corresponding viscosity and antibacterial activity.

In order to explore the correlation between the viscosity of chitosan oligomers-acetic solution and its viscosity average molecular weight (M), and determine the M range with a strong bactericidal effect. A series of chitosan oligomers were obtained by degraded chitosan (728.5 kDa) with dilute acid and chitosan oligomer (101.

Synergistic antimicrobial system based on nisin and α-hydroxy organic acids.

Synergistic antimicrobial is a promising way to overcome microbial contamination in food and drugs. In the study, the synergistic effect between nisin and α-hydroxy organic acids on E. coli and S.

Synergistic antimicrobial effect of nisin-octanoic acid nanoemulsions against E. coli and S. aureus.

Food safety is a major public health concern all over the world. Therefore, the prevention of food contamination is becoming extremely crucial. In this study, an antimicrobial nanoemulsion composed of water-soluble nisin and fat-soluble octanoic acid was successfully prepared.

Separation and Purification of Bamboo Leaf Flavones by Polyvinylpolypyrrolidone Adsorption.

In view of the adsorption performance of polyvinylpolypyrrolidone (PVPP) to flavones, the adsorption and purification of bamboo leaf flavones (BLFs) by PVPP were studied. The flavones solution was adsorbed by PVPP column chromatography, and then establish a relatively effective method for elution and purification of flavones from bamboo leaf. The optimal separation conditions of column chromatography were determined as the following: the feed concentration of 10 mg/mL, the ratio of diameter to height of 1:1.

[In vitro screening of natural compounds with antitumor activity by trypsin].

In order to investigate the feasibility of in vitro screening the antitumor activity of natural compounds by trypsin, porcine trypsin was used to for screening test, which is marked by inhibition of enzyme activity. Four compounds, namely daidzin, genistin, matrine and oxymatrine, were selected as test subjects. The natural antitumor drug camptothecin was used as the control.

Degree and distribution of substitution of hydroxypropyl-β-cyclodextrin in enantioselective liquid-liquid extraction and countercurrent chromatographic enantioseparation.

Nine types of hydroxypropyl-β-cyclodextrin (HP-β-CD) with different degrees and distributions of substitution were synthesised, and nine racemates were selected to investigate the effect of different degrees and distributions of substitution of HP-β-CD on the enantioseparation factor. H NMR and GC/MS were used to characterise the synthesised HP-β-CD. The degree and distribution of substitution had a significant influence on enantioselective liquid-liquid extraction and enantioseparation by countercurrent chromatography.

Immobilization of lipase on silica nanoparticles by adsorption followed by glutaraldehyde cross-linking.

In this study, Candida antarctica lipase B was immobilized on silica (SiO) nanoparticles by physical adsorption, and then cross-linked with glutaraldehyde (GA) to prepare cross-linked immobilized lipase (CLIL). During the condition of 1.28 mg/mL lipase concentration, 25 ℃ temperature, 2 h adsorption time, 0.

Enantioseparation of N-methyl duloxetine, duloxetine, and fluoxetine by countercurrent chromatography using anionic β-cyclodextrin as chiral selector.

Two anionic β-cyclodextrins as chiral selectors were successfully applied in the enantioseparation of N-methyl duloxetine, duloxetine, and fluoxetine by countercurrent chromatography. Sulfobutyl ether-β-cyclodextrin and carboxymethyl-β-cyclodextrin showed opposite enantioselectivity for both duloxetine and N-methyl duloxetine enantiomers. Two biphasic solvent systems, n-hexane: 0.

Hypoglycemic activity and mechanisms of myricetin.

Myricetin has been reported to have a wide variety of beneficial physiological functions. The present study was designed to investigate the mechanism of high purity myricetin, as a hypoglycemic functional component on high fat diet (HFD) fed streptozotocin (STZ) induced diabetic rats. Four-week antihyperglycemic effects of myricetin were assayed.

Immobilization of lipase by dialdehyde cellulose crosslinked magnetic nanoparticles.

Cellulose microcrystalline (MCC) was widely used in pharmaceutical and chemical industries because of its low degree of polymerization and large specific surface area. As its modified form, dialdehyde cellulose (DAC) was used for cross-linking and immobilizing Rhizopus lipase together with magnetic nanoparticles (MNPs) due to its active aldehyde groups. In this study, in order to maintain the original enzyme activity as much as possible and improve the stability of lipase, the Rhizopus lipase was successfully immobilized on the magnetic dialdehyde cellulose nanoparticles (MDC).

Enantioseparation of ondansetron by countercurrent chromatography using sulfobutyl ether-β-cyclodextrin as chiral selector.

Ondansetron, a highly selective 5-hydroxytryptamine 3 receptor antagonist, was successfully enantioseparated by recycling countercurrent chromatography using sulfobutyl ether-β-cyclodextrin as chiral selector. Important factors for the enantioseparation were optimized, including different organic solvent, type of substituted β-cyclodextrin, pH of aqueous phase, concentration of chiral selector, and separation temperature. A biphasic solvent system composed of n-hexane: n-butyl acetate: 0.

Catalytic esterification performance of protease in micro-aqueous system.

Objective: To evaluate the catalytic esterification performance of proteases in micro-aqueous systems and to study the suitable conditions for maintaining protease activity.

Results: It was found that the protease showed better enzyme catalytic activity in the micro-aqueous phase containing 4% boric acid-borax buffer than that of the pure organic phase. The protease activity was easily activated by 0.

Study on the relationship between crosslinking degree and properties of TPP crosslinked chitosan nanoparticles.

In order to reveal the relationship between the degree of crosslinking and the properties of chitosan nanoparticles, a potassium polyvinyl sulfate (PVSK) titration method was established for the determination of free amino group in chitosan, which showed that there was a window effect in the crosslinking degree and particle size of three kinds of molecular weight chitosan cross-linked by different content of tripolyphosphate (TPP), and the nanoparticles with moderate crosslinking degree were smaller. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) showed the moderate degree of cross-linking nanoparticles had strong antibacterial properties. IR analysis showed that the interaction between chitosan nanoparticles with different crosslinking degree and TPP were different.

Preparation and characterization of crosslinked porous starch hemostatic.

In order to develop starch hemostatic materials with excellent hemostatic properties, the preparation of crosslinked porous starch (SPS) with sodium trimetaphosphate (STMP) as cross-linking agent was studied in this paper. When the solid-liquid ratio of porous starch (PS) was 30%, the mass ratio of cross-linking agent to starch was 0.04-1, and the SPS was crosslinked at pH 10.

A Comparison of the Resolution of Selective (+/-)-Glycidyl Butyrate by Using Free and Nano-SiO₂ Immobilized Porcine Pancreatic Lipase.

To explore the hydrolyzed properties of nano-SiO₂ immobilized porcine pancreatic lipase, the selective hydrolysis of immobilized lipase for glycidyl butyrate was compared with the free enzyme. The hydrolysis selectivity of the immobilized biocatalyst was evaluated and compared with the free enzyme using the enantiomeric excess (ee) of resolving racemic glycidyl butyrate as the indicator. The enantiomeric excess of the immobilized biocatalyst could be increased by 4.

Study the effect of trypsin enzyme activity on the screening of applying frontal affinity chromatography.

Frontal affinity chromatography (FAC) combined with enzyme has been widely used for drug screening. In this paper, the effect of target enzyme activity on screening of bioactive compounds was studied through applying FAC. Trypsin with different degree of inactivation were prepared as target enzyme by thermal denaturation.

Preparation of immobilized lipase on magnetic nanoparticles dialdehyde starch.

Dialdehyde starch (DAS) is a kind of modified starch which contains many active aldehyde groups and has good biocompatibility. In this study, magnetic dialdehyde starch nanoparticles were successfully used to immobilize lipase. The lipase was immobilized onto magnetic nanoparticles by using DAS instead of glutaraldehyde as a crosslinker.

Enzymatic acylation of flavone isolated from extractive of bamboo leaves with oleic acid and antioxidant activity of acylated product.

This present study aims to establish a relatively cheap and effective method for preparation of ester of flavone isolated from bamboo-leaf extracts. According to this method, the solubility of bamboo leaf extract in a lipid medium could be improved, which would expand the utilization of bamboo leaf extract. Acylation of flavone with oleic acid was efficient in a system containing dried tert-amyl-alcohol and molecular sieves.

Preparation and properties of gum arabic cross-link binding nisin microparticles.

Nisin is a small cationic peptide composed of 34 amino acid residues, it exhibits a wide spectrum antimicrobial activity against Gram-positive bacteria, but nisin has the disadvantages of poor stability and short duration of antibacterial activity. In order to improve the stability of nisin during food processing and storage period, the gum arabic (GA) is used to get GA-nisin microparticles. The analysis of zeta potential, SEM and FT-IR were used to characterize the combination of GA and nisin, test the antibacterial activity on Staphylococcus aureus and Escherichia coli, the bactericidal effect of GA-nisin microparticles decreased within 24 h compare to free nisin, however, GA-nisin microparticles after 121 °C treatment for 10 min, the activity loss rate is less than free nisin and has better sustained antibacterial effect at 25 °C.

[Research on improving memory impairment of blue lavender volatile oil].

In order to study the potential application value of lavender volatile oil (LVO), the chemical composition of the volatile oil of lavender was analyzed by GC-MS, and the mouse model of Alzheimer's disease (AD) was established. Additionally, the antioxidant enzymes activity of T-SOD, GSH-PX, CAT and MDA content were studied. Experimental results showed that 55 kinds of chemical constituents including terpene, terpene alcohol and ester compounds from LVO were identified, and the content of linalool and linalyl acetate was the highest, accounting for 49.

Utilization of Nano-SiO₂ as a Supporting Material for Immobilization of Porcine Pancreatic Lipase.

Nano-SiO2 is an inexpensive material for enzyme immobilization and has been frequently utilized for this purpose. In addition to its low cost, Nano-SiO2 has several advantages when used as a supporting material, including its lack of toxicity and chemical reactivity, allowing easy fixation of enzymes. In this article, Porcine Pancreatic lipase was non-covalently immobilized on Nano-SiO2.