核桃蛋白酶解物的制备及抗氧化活性

采用碱性蛋白酶对核桃蛋白进行酶解, 检测了所得酶解物的抗氧化能力, 包括对1,1-二苯基-2-三硝基苯肼(DPPH)和羟基自由基(·OH)的清除能力; 利用Sephadex G-25 凝胶层析柱和反相柱对核桃蛋白酶解物进行分离纯化; 采用液相色谱-质谱(LC-ESI-Q-TOF)联用方法测得抗氧化能力最强的多肽的序列为Ala-Gly-Gly-Ala, 其还原力和还原型谷胱甘肽相当.     

Influence of the Degree of Hydrolysis on Functional Properties and Antioxidant Activity of Enzymatic Soybean Protein Hydrolysates

Soybean protein hydrolysates were prepared using two proteolytic enzymes (Alcalase and Protamex) and the degree of hydrolysis (DH) and their functional and antioxidant properties were evaluated. The highest DH value was 20%, with a yield of 19.77% and protein content of 51.64%. The total amino acid content was more than 41% for all protein hydrolysates. The protein hydrolysates from Protamex at pH 2.0 had excellent solubility, emulsifying activity, and foaming capacity, at 83.83%, 95.03 m²/g, and 93.84%, respectively. The water-holding capacity was 4.52 g/g for Alcalase, and the oil-holding capacity was 4.91 g/g for Protamex. The antioxidant activity (62.07%), as measured by the samples’ reaction with DPPH (2,2-diphenyl-1-picrylhydrazyl) and the reducing power (0.27) were the strongest for Protamex. An ABTS activity rate of 70.21% was recorded for Alcalase. These findings indicated a strong potential for the utilization of soybean protein hydrolysates to improve the functional properties and antioxidant activity of soybeans as well as their nutritional values.     

Optimization of Enzymatic Hydrolysis of Perilla Meal Protein for Hydrolysate with High Hydrolysis Degree and Antioxidant Activity

Botanical oils are staple consumer goods globally, but as a by-product of oil crops, meal is of low utilization value and prone to causing environmental problems. The development of proteins in meal into bioactive peptides, such as Perilla peptide, through biotechnology can not only solve environmental problems, but also create more valuable nutritional additives. In the present work, the hydrolysis process of Perilla meal protein suitable for industrial application was optimized with the response surface methodology (RSM) on the basis of single-factor experiments. Alcalase was firstly selected as the best-performing among four proteases. Then, based on Alcalase, the optimal hydrolysis conditions were as follows: enzyme concentration of 7%, hydrolysis temperature of 61.4 °C, liquid-solid ratio of 22.33:1 (mL/g) and hydrolysis time of 4 h. Under these conditions, the degree of hydrolysis (DH) of Perilla meal protein was 26.23 ± 0.83% and the DPPH scavenging capacity of hydrolysate was 94.15 ± 1.12%. The soluble peptide or protein concentration of Perilla meal protein hydrolysate rose up to 5.24 ± 0.05 mg/mL, the ideal yield of which was estimated to be 17.9%. SDS-PAGE indicated that a large proportion of new bands in hydrolysate with small molecular weights appeared, which was different from the original Perilla meal protein. The present data contributed to further, more specific research on the separation, purification and identification of antioxidant peptide from the hydrolysate of Perilla meal protein. The results showed that the hydrolysis of Perilla meal protein could yield peptides with high antioxidant activity and potential applications as natural antioxidants in the food industry.     

Fractionation of Protein Hydrolysates of Fish and Chicken Using Membrane Ultrafiltration: Investigation of Antioxidant Activity

In this work, chicken and fish peptides were obtained using the proteolytic enzymes α-Chymotrypsin and Flavourzyme. The muscle was hydrolyzed for 4 h, and the resulting peptides were evaluated. Hydrolysates were produced from Argentine croaker (Umbrina canosai) with a degree of hydrolysis (DH) of 25.9 and 27.6 % and from chicken (Gallus domesticus) with DH of 17.8 and 20.6 % for Flavourzyme and α-Chymotrypsin, respectively. Membrane ultrafiltration was used to separate fish and chicken hydrolysates from Flavourzyme and α-Chymotrypsin based on molecular weight cutoff of >1,000, <1,000 and >500, and <500 Da, to produce fractions (F1,000, F1,000–500, and F500) with antioxidant activity. Fish hydrolysates produced with Flavourzyme (FHF) and α-Chymotrypsin showed 60.8 and 50.9 % of peptides with a molecular weight of <3 kDa in its composition, respectively. To chicken hydrolysates produced with Flavourzyme and α-Chymotrypsin (CHC) was observed 83 and 92.4 % of peptides with a molecular weight of <3 kDa. The fraction that showed, in general, higher antioxidant potential was F1,000 from FHF. When added 40 mg/mL of FHF and CHC, 93 and 80 % of lipid oxidation in ground beef homogenates was inhibited, respectively. The composition of amino acids indicated higher amino acids hydrophobic content and amino acids containing sulfuric residues for FHF, which showed antioxidant potential.     

Dynamic High Pressure Micro-fluidization Effects on Structure and Physico-chemical Properties of Egg White Protein

The authors dealt with the effects of dynamic high pressure micro-fluidization(untreated and 20―160 MPa treated) on the structure and physico-chemical properties of egg white solutions[6%(mass fraction) or 61.2 mg protein/mL]. Micro-fluidization treatment resulted in a decrease in mean particle size,and little change in solubility. It was found that the residual denaturation enthalpy was decreased with the increase of pressure from 20 to 100 MPa and from 120 to 160 MPa,reaching into the maximum at 160 MPa. ...     

A Practical,One-Pot Preparation of Diisopinocampheylchloroborane

A one-pot preparation of the chiral reducing agent diisopinocampheylchloroborane (Ipc₂BCl) from α-pinene and borane methyl sulfide has been developed. The procedure obviates isolation of the air and moisture sensitive reagent, making it useful for large scale operations. Asymmetric reduction of ketones using the in situ prepared Ipc₂BCl is comparable to that using isolated reagent.     

A Practical,One-Pot Preparation of Diisopinocampheylchloroborane

A one-pot preparation of the chiral reducing agent diisopinocampheylchloroborane (Ipc₂BCl) from Δ-pinene and borane methyl sulfide has been developed. The procedure obviates isolation of the air and moisture sensitive reagent, making it useful for large scale operations. Asymmetric reduction of ketones using the in situ prepared Ipc₂BCl is comparable to that using isolated reagent.     

以蛋清蛋白及半透膜为模板调控碳酸钙的仿生合成

依据生物矿化的基本原理,以蛋清蛋白为基质,透析袋组成隔室,在仿生条件下,诱导碳酸钙的合成。扫描电子显微镜和红外测试结果表明,半透膜和蛋白质虽然直接影响碳酸钙的形貌,但在半透膜和蛋清蛋白调控下生成的碳酸钙均为球霰石型晶体。实验结果表明,半透膜的选择性透过功能不仅限制了蛋白质的自由移动,同时也限制了蛋白质和Ca2+配合物的自由移动,从而为制备特殊形貌的碳酸钙固体提供了基础。     

A Simplified,One-Pot Preparation of Acetobromosugars from Reducing Sugars

ABSTRACT

Acetobromoglycoses continue to be important as glycosyl donors in the synthesis of simple glycosides as well as complex oligosaccharides. From reducing sugars they are usually prepared via their peracetates in two steps. In the first step, sugars are converted to their peracetates using pyridine and acetic anhydride^1,2 and the acetates are then converted in a second step to acetobromosugars using a solution of hydrogen bromide in glacial acetic acid(HBr/HOAc).² Although not in use very often Redemann and Niemann³ as well as Lemieux⁴ have described one-pot methods for the preparation of acetobromoglucose wherein the reducing sugar is first treated with acetic anhydride in the presence of sulfuric acid³ or perchloric acid⁴ respectively to afford the peracetate. Direct conversion of the peracetate to its 1-bromo-derivative, in yields ranging from 80-87%, was then achieved by either treating the solution of the peracetate with gaseous HBr³ or with bromine in the presence of red phosphorus.⁴ In another approach to a one-pot method Humoller⁵ prepared tri-O-acetyl-β-L-arabinopyranosyl bromide in 40% yield by passing anhydrous HBr gas through a suspension of L-arabinose in acetic anhydride. By an essentially similar method Dale⁶ obtained acetobromosugars in yields ranging from 26-77% depending upon the sugar. Because acetobromosugars are the compounds most frequently used for synthesizing numerous other sugar derivatives, we thought it would be worthwhile to report our recent observation that acetic anhydride and HBr/HOAc can be used with advantage for the preparation of acetobromosugars.     

An Improved One-Pot Method for the Preparation of 2-Substituted 1H-Perimidines

2-substituted 1H-perimidines are readily prepared, in high yields, by refluxing a mixture of sodium pyrosulfite, an aldehyde, and 1, 8-diaminonaphthalene in aqueous ethanol or N, N-dimethylformamide. The method is of wide applicability except from araldehydes bearing a strong electron-withdrawing group (-CN, -NO₂).     

用高温热水解法制备高活性TiO2纳米微晶光催化剂

采用钛酸四西酯在有机溶剂中高温热水解与结晶同时进行的方法，制备了二氧化钛纳米微晶光催化剂．以XRD、BET、TEM、TG和DTA等方法对获得的微晶进行了表征．所制得的TiO2纳米微晶平均值径约为12nm，比表面积在100m2·g-1以上，并能在报宽的煅烧温度范围内保持锐钛矿型晶体结构．将它应用于光分解甲基橙，具有高的光催化活性．     

Preparation of Antioxidant Protein Hydrolysates from Pleurotus geesteranus and Their Protective Effects on H2O2 Oxidative Damaged PC12 Cells

Pleurotus geesteranus is a promising source of bioactive compounds. However, knowledge of the antioxidant behaviors of P. geesteranus protein hydrolysates (PGPHs) is limited. In this study, PGPHs were prepared with papain, alcalase, flavourzyme, pepsin, and pancreatin, respectively. The antioxidant properties and cytoprotective effects against oxidative stress of PGPHs were investigated using different chemical assays and H₂O₂ damaged PC12 cells, respectively. The results showed that PGPHs exhibited superior antioxidant activity. Especially, hydrolysate generated by alcalase displayed the strongest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (91.62%), 2,2-azino-bis (3-ethylbenzothia zoline-6-sulfonic acid) (ABTS) radical scavenging activity (90.53%), ferric reducing antioxidant power, and metal ion-chelating activity (82.16%). Analysis of amino acid composition revealed that this hydrolysate was rich in hydrophobic, negatively charged, and aromatic amino acids, contributing to its superior antioxidant properties. Additionally, alcalase hydrolysate showed cytoprotective effects on H₂O₂-induced oxidative stress in PC12 cells via diminishing intracellular reactive oxygen species (ROS) accumulation by stimulating antioxidant enzyme activities. Taken together, alcalase hydrolysate of P. geesteranus protein can be used as beneficial ingredients with antioxidant properties and protective effects against ROS-mediated oxidative stress.     

一锅法合成二硫醚的简便制备过程研究

双（三氯甲基）碳酸酯与三苯基膦反应生成的二氯三苯基膦在三乙胺存在下与 硫酚（醇）反应，合成了一系列收率良好的二硫醚化合物。该过程采用“一锅法” ，操作方便，后处理简单，条件温和，提供了一条合成二硫醚的重要路线。     

Bioluminescent Enzymatic Assay as a Tool for Studying Antioxidant Activity and Toxicity of Bioactive Compounds

A bioluminescent assay based on a system of coupled enzymatic reactions catalyzed by bacterial luciferase and NADH:FMN‐oxidoreductase was developed to monitor toxicity and antioxidant activity of bioactive compounds. The assay enables studying toxic effects at the level of biomolecules and physicochemical processes, as well as determining the toxicity of general and oxidative types. Toxic and detoxifying effects of bioactive compounds were studied. Fullerenols, perspective pharmaceutical agents, nanosized particles, water‐soluble polyhydroxylated fullerene‐60 derivatives were chosen as bioactive compounds. Two homologous fullerenols with different number and type of substituents, C₆₀O_2–4(OH)_20–24 and Fe_0.5C₆₀(OH) _xO_y (x + y = 40–42), were used. They suppressed bioluminescent intensity at concentrations >0.01 g L^?1 and >0.001 g L^?1 for C₆₀O_2–4(OH)_20‐24 and Fe_0.5C₆₀(OH)_xO_y, respectively; hence, a lower toxicity of C₆₀O_2–4(OH)_20–24 was demonstrated. Antioxidant activity of fullerenols was studied in model solutions of organic and inorganic oxidizers; changes in toxicities of general and oxidative type were determined; detoxification coefficients were calculated. Fullerenol C₆₀O_2–4(OH)_20–24 revealed higher antioxidant ability at concentrations 10^?17?10^?5 g L^?1. The difference in the toxicity and antioxidant activity of fullerenols was explained through their electron donor/acceptor properties and different catalytic activity. Principles of bioluminescent enzyme assay application for evaluating the toxic effect and antioxidant activity of bioactive compounds were summarized and the procedure steps were described.     

超声辅助化学还原法制备高活性Co-B非晶态合金催化剂

采用超声辅助KBH4化学还原Co(OH)2胶体法制备了粒径均匀的Co-B非晶态合金.在乙腈液相选择性加氢制取乙胺反应中,与传统化学还原法制备的Co-B非晶态合金催化剂相比,该催化剂具有很高的催化活性.这归因于其Co活性位的高度分散、Co活性位对氢的强吸附,以及Co-B非晶态合金间强电子相互作用.     

Influence of Enzymatic Hydrolysis and Molecular Weight Fractionation on the Antioxidant and Lipase / α-Amylase Inhibitory Activities In Vitro of Watermelon Seed Protein Hydrolysates

This study aims to evaluate the potential in vitro antioxidant and anti-obesity activities of watermelon seed protein hydrolysates (WSPH) obtained using different combinations of enzymes alcalase–proteinase K (ALC-PK) and alcalase–actinidin (ALC-ACT). There was a direct relationship between the degree of hydrolysis (DH) and the biological activities of the WSPH, with the highest DPPH (approximately 85%) and lipase inhibitory activities (≈59%) appreciated at DH of 36–37% and 33–35% when using ALC-PK and ALC-ACT, respectively. Following molecular weight fractionation, the ALC-PK WSPH < 3 kDa (F1) assayed at 1 mg.mL⁻¹ had the highest DPPH-radical scavenging (89.22%), ferrous chelating (FC) (79.83%), reducing power (RP) (A 0.51), lipase inhibitory (71.36%), and α-amylase inhibitory (62.08%) activities. The amino acid analysis of ALC-PK WSPH and its fractions revealed a relationship between the biological activity of the extracts and their composition. High contents of hydrophobic amino acids, arginine, and aromatic amino acids were related to high antioxidant, lipase inhibitory, and α-amylase inhibitory activities in the extracts, respectively. Overall, this study revealed that underutilized protein sources such as WSPH, using the appropriate combination of enzymes, could result in the generation of new ingredients and compounds with powerful antioxidant and anti-obesity activities with promising applications as nutraceuticals or functional foods.     

A Convenient,Highly Efficient One-Pot Preparation of Peracetylated Glycals From Reducing Sugars

ABSTRACT

A convenient, highly efficient, one-pot, three-step procedure has been developed for the synthesis of peracetylated glycal derivatives from various reducing sugars including D-glucose, D-galactose, L-rhamnose, L-arabinose, D-maltose, D-lactose, and maltotriose. This procedure involves peracetylation of the reducing sugars with acetic anhydride and HBr/acetic acid followed by the transformation of the anomeric acetates to the corresponding bromides with additional HBr/acetic acid and finally reductive elimination of the 1-bromo and 2-acetoxy groups with Zn/CuSO₄·5H₂O in acetic acid/water containing sodium acetate. The overall yields of purified peracetylated glycals from the corresponding sugars range from 50 - 98%.

     

A High Yielding, One-Pot, Triton-B Catalyzed Synthesis of Dithiocarbamates Using Alcoholic Tosylates

Summary. A novel process for the one-step chemoselective conversion of alcoholic tosylates into dithiocarbamates as protected amines was developed using benzyltrimethylammoniumhydroxide (Triton-B) in presence of carbon disulfide. Thus, dithiocarbamates of different amines were prepared in very good to excellent yields. This protocol is mild, chemoselective, and efficient compared to other reported methods. Present address: Institute of Organic and Biomolecular Chemistry, Georg-August University, D-37077, G?ttingen, Germany     

New,Efficient, Selective,and One-Pot Method for Acylation of Amines

Hydrazine hydrate with acetic and propionic acids was an efficient reagent for acylation of primary and secondary amines at reflux temperatures. The reported one-pot method is high-yielding, simple, mild, and inexpensive.     

苯乙烯协助水热制备高催化活性ZnO管

采用苯乙烯微球为模板水热合成了直径为1~2μm,管壁厚度约200nm的ZnO管。用SEM和XRD对制得的样品进行表征,结果表明,醋酸锌浓度和水热时间在ZnO管的制备过程中起到重要作用。在实验结果的基础上,提出了ZnO管的形成机理。紫外-可见吸收光谱计算出ZnO管的禁带宽度为2.96eV,合成的ZnO管对罗丹明B具有很高的紫外光催化活性。