[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. The inhibitory effect was detected by two experimental methods: direct detection of trypsin activity inhibition and hydrolysis of bovine serum albumin by trypsin. The results showed the inhibitory effects of the four natural compounds on trypsin, and the inhibition rates of the four natural compounds were significantly different. The enzyme activity assay showed that the inhibitory effect of matrine was better than that of oxymatrine, indicating that trypsin had a good screening resolution. The inhibitory effect was significantly increased with the increased ratio of sample to trypsin, suggesting the structure-activity correlation and dose-effect correlation of the screening methods. Altogether, the experimental method of screening antitumor activity of natural compounds by trypsin has good application values. Since porcine trypsin is similar to human trypsin in terms of molecular structure and performance, it is more applicable for screening of antitumor efficacy of natural pharmacodynamic compounds.

Method for enhancing bioavailability of myricetin based on self-assembly of casein-myricetin nanomicelles.

In order to expand the application in the medical field and enhance pharmacological effects, casein-myricetin nanomicelles were prepared by the self-assembly method and characterised by ultraviolet-visible spectroscopy and Fourier transform infrared spectroscopy. The parameters in self-assembly were optimised according to the factors of particle size, encapsulation yield, and drug loading. The result showed a pH of 5.5, a casein concentration of 2 mg/ml, a mass ratio of casein to myricetin of 8:1, ultrasonic power of 300 W, ultrasonic time of 5 min and ethanol volume of 7 ml were the optimal conditions. The situ cycle intestinal perfusion methods indicated that casein-myricetin nanomicelles can be more easily absorbed by small intestine than myricetin standard sample. Therefore, casein micelles are effective for improving the water solubility of myricetin.

Surfactant-modified Aspergillus oryzae lipase as a highly active and enantioselective catalyst for the kinetic resolution of (RS)-1-phenylethanol.

The lipase from Aspergillus oryzae was modified with a surfactant and then observed to exhibit high catalytic efficiency and enantioselectivity for the kinetic resolution of (RS)-1-phenylethanol. The influential factors of the modified-lipase preparation were investigated, including the surfactant source, the organic cosolvent, and the buffer pH. The optimum modification conditions were found with a surfactant of polyoxyethylene sorbitan monopalmitate, an organic cosolvent of tetrahydrofuran and a phosphate buffer of pH 7.0. In the transesterification of (RS)-1-phenylethanol with vinyl acetate, the surfactant-modified lipase showed excellent enantioselectivity for the R-isomer (E > 200), giving an enantiomeric excess of higher than 99% for (R)-1-phenylethyl acetate at 46.8% conversion with the reaction time of 2 h at 30 °C. The enzymatic activity had barely altered after 30 days even at 50 °C when it was saved in a powdered state. The results indicated that the modification strategy was useful and highly efficient, and that modified A. oryzae lipase was a promising biocatalyst in the kinetic resolution of (RS)-1-phenylethanol.

[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 49.71% of the total volatile oil. The ability of mouse platform memory was improved significantly. The levels of GSH-PX, CAT and T-SOD of mouse brain tissue in the treatment group were significantly higher than those in the model group (P<0.05). The level of MDA reached the maximum value in the model group, while there was no notable difference between the levels of MDA in the drug group and the normal group. The result indicated the significant oxidative activity of LVO, the possibility of induced oxidative stress reduction in neurons, and the reversal effect of memory acquired disorder.

Efficient kinetic resolution of (RS)-1-phenylethanol by a mycelium-bound lipase from a wild-type Aspergillus oryzae strain.

A mycelium-bound lipase from Aspergillus oryzae (AOL) exhibited excellent enantioselectivity for kinetic resolution of (RS)-1-phenylethanol ((RS)-1-PE) in organic solvent. The various reaction parameters affecting the conversion and enantioselectivity were studied, including type of acyl donor, solvent, molar ratio, temperature, enzyme amount, and substrate concentration. The optimum reaction conditions were found to be transesterification with vinyl acetate at 30 °C in methyl tert-butyl ether with a vinyl acetate: (RS)-1-PE molar ratio of 1:1 and an enzyme concentration of 60 g/L. At the optimum reaction conditions, the conversion could reach above 46% with >99% enantiomeric excess of the product, (R)-1-phenylethyl acetate, when the substrate concentration was below 1.4 M. The enzyme displayed an excellent enantioselectivity with an E-value of >200 and a strong tolerance for high substrate concentration of up to 1.8 M. Those results indicated that AOL was a promising biocatalyst in the kinetic resolution of (RS)-1-PE.

Covalent immobilization of α-amylase on magnetic particles as catalyst for hydrolysis of high-amylose starch.

Enzyme immobilized on magnetic particles can be used as efficient recoverable biocatalysts under strong magnetic response. To enable re-use of enzyme, modified Fe3O4 particles were used as carrier to immobilize α-amylase in this paper. Firstly, the surface of Fe3O4 particles were coated with amino groups by direct using TEOS (tetraethoxysilane) followed by treatment with APTES (3-aminopropyltriethoxysilane) and then carboxylated by reacting it with succinic anhydride. In addition, the effect of the immobilization condition on enzyme activity recovery and immobilization efficiency were investigated. The results showed that the optimal immobilization occurred under following conditions: pH 5.5, 40°C, enzyme concentration of 20mgmL(-1), reaction time for 36h. Using immobilized α-amylase as biocatalyst, the optimum pH and temperature for hydrolysis were observed to be 6.5 and 60°C. The kinetics of hydrolysis reaction were studied using Michaelis-Menten equation. The affinity constant (Km) and maximum reaction rate (vmax) of magnetic particles immobilization α-amylase (MPIA) was 0.543mgmL(-1) and 1.321mgmin(-1) compared to those of 0.377mgmL(-1) and 6.859mgmin(-1) of free enzyme. After immobilization, enzymatic activity, storage stability, thermo-stability, and reusability of MPIA were found superior to those of the free one. MPIA maintained 86% enzyme activity after 30 days and maintained 78% enzyme activity after recycling six times.

Optimization of technological parameters for preparation of lycopene microcapsules.

Lycopene belongs to the carotenoid family with high degree of unsaturation and all-trans form. Lycopene is easy to isomerize and auto oxide by heat, light, oxygen and different food matrices. With an increasing understanding of the health benefit of lycopene, to enhance stability and bioavailability of lycopene, ultrasonic emulsification was used to prepare lycopene microcapsules in this article. The results optimized by response surface methodology (RSM) for microcapsules consisted of four major steps: (1) 0.54 g glycerin monostearate was fully dissolved in 5 mL ethyl acetate and then added 0.02 g lycopene to form an organic phase, 100.7 mL distilled water which dissolved 0.61 g synperonic pe(R)/F68 as the aqueous phase; (2) the organic phase was pulled into the aqueous phase under stirring at 60 °C water bath for 5 min; (3) the mixture was then ultrasonic homogenized at 380 W for 20 min to form a homogenous emulsion; (4) the resulting emulsion was rotary evaporated at 50 °C water bath for 10 min under a pressure of 20 MPa. Encapsulation efficiency (EE) of lycopene microcapsules under the optimized conditions approached to 64.4%.

Preparation of chitosan nanoparticles as carrier for immobilized enzyme.

This work investigated the preparation of chitosan nanoparticles used as carriers for immobilized enzyme. The morphologic characterization of chitosan nanoparticles was evaluated by scanning electron microscope. The various preparation methods of chitosan nanoparticles were discussed and chosen. The effect of factors such as molecular weight of chitosan, chitosan concentration, TPP concentration, and solution pH on the size of chitosan nanoparticles was studied. Based on these results, response surface methodology was employed. The results showed that solution pH, TPP concentration, and chitosan concentration significantly affected the size of chitosan nanoparticles. The adequacy of the predictive model equation for predicting the magnitude orders of the size of chitosan nanoparticles was verified effectively by the validation data. Immobilization conditions were investigated as well. The minimum particles size was about 42 +/- 5 nm under the optimized conditions. The optimal conditions of immobilization were as follows: one milligram of neutral proteinase was immobilized on chitosan nanoparticles for about 15 min at 40 degrees C. Under the optimized conditions, the enzyme activity yield was 84.3%.

[Study on the extraction of the active component in Atractylode macrocephala with ultrasonic wave technology optimized by the response surface method].

OBJECTIVE: To create Atractylode macrocephala inspissation decoction pieces. The effect of ultrasonic wave on extraction of the active components in A. macrocephala was studied in a water solution. METHOD: The factors including the ratio of material to liquid, ultrasonic power, ultrasonic time, soaking time, particle size etc, were studied. The best extraction method was found through the response surface method. RESULT: The best extraction method was found as follows: the granularity of material 0.1 mm, the repetition times of ultrasonic process 3 times, the soaking time before the ultrasonic process 30 min, the ratio of liquid to material 10:1, the soaking time after the ultrasonic process 2.6 h, the time of the ultrasonic wave 15.5 min, the power of the ultrasonic wave 531 W, the rate of reservation of active components 88.5%, the rate of inspissation 1.6. CONCLUSION: The ultrasonic wave can used in the extraction of the active components in A. macrocephala and a model equation that can be used to predict the experiment was get through the response surface method.