Evaluation of Enzyme Inhibitory Activity of Flavonoids by Polydopamine-Modified Hollow Fiber-Immobilized Xanthine Oxidase

In this study, a polydopamine (PDA)-modified hollow fiber-immobilized xanthine oxidase (XOD) was prepared for screening potential XOD inhibitors from flavonoids. Several parameters for the preparation of PDA-modified hollow fiber-immobilized XOD, including the dopamine concentration, modification time, XOD concentration and immobilization time, were optimized. The results show that the optimal conditions for immobilized XOD activity were a dopamine concentration of 2.0 mg/mL in 10.0 mM Tris-HCl buffer (pH 8.5), a modification time of 3.0 h, an XOD concentration of 1000 μg/mL in 10.0 mM phosphate buffer (pH 7.5) and an immobilization time of 3.0 h. Subsequently, the enzymatic reaction conditions such as the pH value and temperature were investigated, and the enzyme kinetics and inhibition parameters were determined. The results indicate that the optimal pH value (7.5) and temperature (37 °C) of the PDA-modified hollow fiber-immobilized XOD were consistent with the free enzyme. Moreover, the PDA-modified hollow fiber-immobilized XOD could still maintain above 50% of its initial immobilized enzyme activity after seven consecutive cycles. The Michaelis–Menten constant (Km) and the half-maximal inhibitory concentration (IC50) of allopurinol on the immobilized XOD were determined as 0.25 mM and 23.2 μM, respectively. Furthermore, the PDA-modified hollow fiber-immobilized XOD was successfully applied to evaluate the inhibitory activity of eight flavonoids. Quercetin, apigenin, puerarin and epigallocatechin showed a good inhibition effect, and their percentages of inhibition were (79.86 ± 3.50)%, (80.98 ± 0.64)%, (61.15 ± 6.26)% and (54.92 ± 0.41)%, respectively. Finally, molecular docking analysis further verified that these four active compounds could bind to the amino acid residues in the XOD active site. In summary, the PDA-modified hollow fiber-immobilized XOD is an efficient method for the primary screening of XOD inhibitors from natural products.

Risk Factors for the Occurrence and Progression of Posttraumatic Elbow Stiffness: A Case-Control Study of 688 Cases

Background: Elbow stiffness is a severe complication after trauma. Surgical or conservative treatments may be ineffective for restoring functional elbow motion. We aim to evaluate intrinsic and extrinsic factors for the occurrence and severity of elbow stiffness.Methods: This retrospective case–control study included mild/moderate stiffness, severe stiffness, and non-stiffness groups between January 2011 and December 2017 at a single orthopedic center. Multivariable logistic regression analysis and subgroup analysis were used to evaluate age, gender, body mass index, muscle strength, fracture type and site, injury mechanism, immobilization time, elbow dysfunction time, multiple surgeries, nerve symptoms, physical therapy, smoking and alcohol abuse, and dominant hand of stiff elbow as potential risk factors for the occurrence and severity of elbow stiffness.Results: There were 461 patients in the stiffness group and 227 patients in the non-stiffness group. The odds ratios (ORs) of the age, muscle strength, and injury mechanism were 0.960, 0.333, and 0.216 for the occurrence of elbow stiffness. In subgroup evaluation, increased cast immobilization time might be a risk factor for patients receiving conservative therapies (OR = 2.02; p = 0.014). In the evaluation on factors for progression of elbow stiffness, “multiple surgeries” might be a risk factor in surgical treatment by subgroup analysis (OR = 1.943; p = 0.026). Nevertheless, alcohol abuse might increase severity of elbow stiffness in conservatively treated patients (OR = 3.082; p = 0.025).Conclusion: Increased cast immobilization time in the conservative therapy might be a risk factor for stiffness occurrence. Multiple surgeries might be risk factors for stiffness progression. Alcohol abuse potentially increased stiffness severity after conservative treatment.

Prey and Venom Efficacy of Male and Female Wandering Spider, Phoneutria boliviensis (Araneae: Ctenidae)

Spiders rely on venom to catch prey and few species are even capable of capturing vertebrates. The majority of spiders are generalist predators, possessing complex venom, in which different toxins seem to target different types of prey. In this study, we focused on the trophic ecology and venom toxicity of Phoneutria boliviensis F. O. Pickard-Cambridge, 1897, a Central American spider of medical importance. We tested the hypothesis that its venom is adapted to catch vertebrate prey by studying its trophic ecology and venom toxicity against selected vertebrate and invertebrate prey. We compared both trophic ecology (based on acceptance experiments) and toxicity (based on bioassays) among sexes of this species. We found that P. boliviensis accepted geckos, spiders, and cockroaches as prey, but rejected frogs. There was no difference in acceptance between males and females. The venom of P. boliviensis was far more efficient against vertebrate (geckos) than invertebrate (spiders) prey in both immobilization time and LD50. Surprisingly, venom of males was more efficient than that of females. Our results suggest that P. boliviensis has adapted its venom to catch vertebrates, which may explain its toxicity to humans.

Phytochemical Study and Antidepressant Effect of Essential Oil of Apium graveolens L.

Background and Purpose: Depression is a common and debilitating disease.The aim of this study was to investigate the chemical composition of Apium graveolens essential oil and its anti-depressant effect in mice and the effect on motor balance, serum and brain antioxidant capacity. Materials and Methods: 60 mice were randomly divided into 6 groups (N=10), Control, reserpine 5 mg/kg IP, reserpine + fluoxetine 20mg/kg, reserpine + essential oil (50, 75 and 100 mg/kg). The intervention group received 5 mg/kg reserpine and 18 hours later, essential oil (50, 75 and 100 mg/kg). Assessment of depression done with forced swimming and open field tests and motor balance with a Rotarod. Serum and brain antioxidant capacity and malondialdehyde levels were measured. Results: Reserpin increased the immobilization time in the forced swimming test, the number of motor units in the open field test, serum and brain malondialdehyde and reduced the antioxidant capacity and the motor balance. Fluoxetine and essential oil of Apium graveolens 50 and 75 mg/kg reduced the time of immobilization time, number of motor units, serum and brain malondialdehyde and increased serum and brain antioxidant capacity and motor balance. Apium graveolens essential oil 100 mg/kg increased serum antioxidant capacity and reduced number of motor units. Conclusion: Chemical compounds of essential oil of Apium graveolens have antioxidant, anti-inflammatory and regulating of chemical neurotransmitters properties that are known mechanisms of depression.

Phytochemical Study and Antidepressant Effect of Essential Oil of Apium graveolens L.

Background and Purpose: Depression is a common and debilitating disease.The aim of this study was to investigate the chemical composition of Apium graveolens essential oil and its anti-depressant effect in mice and the effect on motor balance, serum and brain antioxidant capacity. Materials and Methods: 60 mice were randomly divided into 6 groups (N=10), Control, reserpine 5 mg/kg IP, reserpine + fluoxetine 20mg/kg, reserpine + essential oil (50, 75 and 100 mg/kg). The intervention group received 5 mg/kg reserpine and 18 hours later, essential oil (50, 75 and 100 mg/kg). Assessment of depression done with forced swimming and open field tests and motor balance with a Rotarod. Serum and brain antioxidant capacity and malondialdehyde levels were measured. Results: Reserpin increased the immobilization time in the forced swimming test, the number of motor units in the open field test, serum and brain malondialdehyde and reduced the antioxidant capacity and the motor balance. Fluoxetine and essential oil of Apium graveolens 50 and 75 mg/kg reduced the time of immobilization time, number of motor units, serum and brain malondialdehyde and increased serum and brain antioxidant capacity and motor balance. Apium graveolens essential oil 100 mg/kg increased serum antioxidant capacity and reduced number of motor units. Conclusion: Chemical compounds of essential oil of Apium graveolens have antioxidant, anti-inflammatory and regulating of chemical neurotransmitters properties that are known mechanisms of depression.

Degradation of chlorpyrifos in contaminated soil by immobilized laccase

In the present study, the embedding-crosslinking method was used to immobilize fungal laccase, and to determine the suitable conditions for immobilization by measuring various activities of the immobilized laccase. In addition, the immobilized laccase was further employed to repair chlorpyrifos-contaminated soil, and then the degradation rates of chlorpyrifos were measured under different conditions. Based on the results, the appropriate conditions for the method of mbedding-crosslinking were found to be as follows: concentration of sodium alginate ? 3 %, concentration of glutaraldehyde ? 1 %, crosslinking time ? 6h, volume of crude laccase ? 60 ml, and immobilization time ? 4 h. After 48 h, the degradation rate of chlorpyrifos in soil could reach at least 70 % by the use of immobilized laccase that was prepared by the method of embedding-crosslinking under different environmental conditions.

Optimization of esterification activity of lipase from Candida rugosa immobilized using microwave irradiation

Lipases are very efficient biocatalysts with wide application in synthesis of important ingredients of food, cosmetics and pharmaceutical products, due to their capacity to catalyze both, ester synthesis and ester hydrolysis. The preparation of stable and active immobilized derivatives of lipases is necessity for their application in industrial enzymatic processes. In this work, the optimization of lipase from C. rugosa immobilization by microwave irradiation was performed, since it was previously reported that immobilization process can be drastically accelerated by means of microwave irradiation, even resulting with slight increase of lipase activity. Eupergit?, commercial support with active epoxy groups, was used as immobilization support. In first stage of our study, the immobilization time and ionic strength of immobilization buffer were optimized. It was found out that the highest immobilized activity can be achieved at high ionic strengths (1 M buffer) after 3 min, while further increase of immobilization time led to decrease of lipase activity. Then, the immobilized derivative obtained at optimum conditions was applied in synthesis of amyl isobutyrate in organic solvent. Key reaction factors (temperature, water concentration, immobilized lipase concentration, and substrate molar ratio) were optimized using response surface methodology. The substrate conversion higher above 85% was achieved in our study. The statistical analysis revealed that each of analyzed factors had significant effect on yield of ester, with initial enzyme concentration and substrate molar ratio being the most prominent factors. The second-order regression model that describes the effect of all four factors on substrate conversion was established. The optimum values of factors were: temperature 50?C, initial immobilized enzyme concentration 220 mg ml-1, added water concentration 0.1% (v/v), and molar ratio acid/alcohol 2.5.

The Single Factor Research on the Optimal Conditions of Laccase Immobilization on the Resin

The optimal conditions of immobilization were obtained: the optimization of crosslinking agent concentration 10%, crosslinking time 2 hours、crosslinking temperature 40°C, pH 6.0, enzyme dilute multiples 500, PEB ion concentration 2.0M, immobilization time 6h and immobilization temperature 30°C, respectively.