应用原子-键电负性均衡方法预测超氧化物歧化酶催化反应的活性部位

应用原子-键电负性均衡方法计算了超氧化物歧化酶的电荷分布和Fukui函数. 结果表明, 超氧化物歧化酶活性中心与超氧阴离子自由基作用时, 金属离子电荷转移在0.1 e～0.3 e之间, 而配体原子等的电荷转移却很小; 同时金属离子的Fukui函数大于配位原子的Fukui函数. 超氧化物歧化酶活性中心与抑制剂作用失活后, 金属离子的Fukui函数小于抑制剂中配位原子的Fukui函数. 电荷转移和Fukui函数表明, Mn, Fe和Cu离子分别是含锰、铁和铜锌超氧化物歧化酶的活性中心部位, 该预测不仅与量子化学理论计算一致, 而且与实验现象相吻合.     

水溶性席夫碱型锰配合物的合成、表征及其模拟超氧化物歧化酶活性研究

以水杨醛为母体, 与胺类化合物缩合形成席夫碱配体, 用分子自组装法合成了一系列水溶性席夫碱型金属锰单核、双核配合物. 通过元素分析、红外光谱对配合物进行了表征, 采用邻苯三酚自氧化法测定了配合物的超氧化物歧化酶(SOD)活性. 结果表明, 这些水溶性锰配合物具有良好的SOD活性.     

Lipolytic Postbiotic from Lactobacillus paracasei Manages Metabolic Syndrome in Albino Wistar Rats

The current study investigates the capacity of a lipolytic Lactobacillus paracasei postbiotic as a possible regulator for lipid metabolism by targeting metabolic syndrome as a possibly safer anti-obesity and Anti-dyslipidemia agent replacing atorvastatin (ATOR) and other drugs with proven or suspected health hazards. The high DPPH (1,1-diphenyl-2-picrylhydrazyl) and ABTS [2,2′-azino-bis (3-ethyl benzothiazoline-6-sulphonic acid)] scavenging activity and high activities of antioxidant enzyme such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-px) of the Lactobacillus paracasei postbiotic (cell-free extract), coupled with considerable lipolytic activity, may support its action against metabolic syndrome. Lactobacillus paracasei isolate was obtained from an Egyptian cheese sample, identified and used for preparing the postbiotic. The postbiotic was characterized and administered to high-fat diet (HFD) albino rats (100 and 200 mg kg⁻¹) for nine weeks, as compared to atorvastatin (ATOR; 10 mg kg⁻¹). The postbiotic could correct the disruption in lipid metabolism and antioxidant enzymes in HFD rats more effectively than ATOR. The two levels of the postbiotic (100 and 200 mg kg⁻¹) reduced total serum lipids by 29% and 34% and serum triglyceride by 32–45% of the positive control level, compared to only 25% and 35% in ATOR’s case, respectively. Both ATOR and the postbiotic (200 mg kg⁻¹) equally decreased total serum cholesterol by about 40% and 39%, while equally raising HDL levels by 28% and 30% of the positive control. The postbiotic counteracted HFD-induced body weight increases more effectively than ATOR without affecting liver and kidney functions or liver histopathology, at the optimal dose of each. The postbiotic is a safer substitute for ATOR in treating metabolic syndrome.     

In Vitro Screening of Indigenous <Emphasis Type="Italic">Lactobacillus</Emphasis> Isolates for Selecting Organisms with Better Health-Promoting Attributes

Lactobacilli have several attributes that provide health benefits to the host. The aim of this study was to screen indigenous lactobacilli from human gut and fermented foods for such attributes as production of β- and α-galactosidase and also their ability to reduce serum cholesterol. Lactobacilli were cultured on MRS broth and β-galactosidase activity was determined using o-nitrophenyl-β-D-galactopyranoside (ONPG) as a substrate. Three isolates Lactobacillus fermentum GPI-3 and L. fermentum GPI-6 and Lactobacillus salivarius GPI-1(S) showed better β-galactosidase activity than the standard strains Lactobacillus rhamnosus GG (LGG) and Lactobacillus plantarum ATCC 8014. The isolates showed variability in assimilating cholesterol during growth. Several isolates showed excellent cholesterol-lowering ability compared to standard strains LGG and L. plantarum ATCC 8014. Isolate L. rhamnosus SCB being the highest acid producer (pH 4.38) also showed the highest cholesterol reduction compared to other strains including standard strains. The ability of these isolates to produce α-galactosidase was also studied and the maximum α-galactosidase activity was found in isolate L. salivarius GPI-1(S) followed by L. fermentum FA-5 and Lactobacillus helveticus FA-7. This study therefore reports Lactobacillus isolates that have superior probiotic properties when compared to the standard strains; hence, they could be considered as potential probiotic strains, which can provide health benefits to the Indian population.     

Fine tuning the reactivity of corrole-based catalytic antioxidants

In order to determine the electronic factors that may affect the catalytic antioxidant activity of water-soluble metallocorroles a series of 10-aryl-5,15-pyridinium manganese(III) corroles was prepared. These complexes were examined regarding the effect of the C(10) substituent on the Mn(IV)/Mn(III) redox potentials, catalytic rate constants for decomposition of HOONO, prevention of tyrosine nitration, and superoxide dismutase activity. This structure-activity relationship investigation provides new insight regarding the mechanism by which manganese(III) corroles act as catalytic antioxidants. It also discloses the superiority of the C(10)-anysil-substituted complex in all examined aspects.     

Prebiotic activity of polysaccharides extracted from Gigantochloa levis (Buluh beting) shoots

Bamboo shoot crude polysaccharides (BSCP) extracted from the shoots of Gigantochloa levis gave about 3.27 ± 0.18% on dry basis and a very minute percentage of protein (0.02 ± 0.01%). The molecular weight of BSCP estimated by gel chromatography was found to be around 7.49 × 103 Da, while the molecular weights of purified fractions (F1 to F5) were around 1550.96, 1471.63, 1685.78, 1691.61 and 1551.67 Da, respectively. The FTIR spectrum of BSCP revealed the possibility that the extract contains β-glucan, which can be considered a valuable compound for the medical and food industries. These relate to the resistance of BSCP towards artificial human gastric juice which is more than 99%. Prebiotic activity tested using BSCP as a carbon source showed significant increase in the growth of B. animalis ATCC 1053, B. longum BB 536 and L. acidophilus ATCC 4356 as compared to the use of FOS. Survivality of S. choleraesuis JCM 6977 was found to be slower in both BSCP and FOS. Study conducted reflects a good sign for the BSCP to be exploited as a promising prebiotic.     

2D-DIGE proteomic analysis of changes in estrogen/progesterone-induced rat breast hyperplasia upon treatment with the Mongolian remedy RuXian-I

RuXian-I has traditionally been used as a remedy for breast hyperplasia in the Inner Mongolia Autonomous Region of China. As a first step toward the investigation of biomarkers associated with RuXian-I treatment, a proteome-wide analysis of rat breast tissue was conducted. First, rat breast hyperplasia was induced by injection of estradiol and progesterone. After treatment with RuXian-I, there is a marked decrease in the hyperplasia, as can be shown by decreases in the nipple diameter and the pathological changes in breast. Subsequently, we used an approach that integrates size-based 2D-DIGE, MALDI-TOF/TOF-MS, and bioinformatics to analyze data from the control group, the model group and the RuXian-I treatment group. Using this approach, seventeen affected proteins were identified. Among these, 15 (including annexin A1, annexin A2, superoxide dismutase [Mn], peroxiredoxin-1, translationally-controlled tumor protein and a B-crystallin) were significantly up-regulated in the model group and down-regulated upon treatment with RuXian-I, and two (Tpil protein and myosin-4) have the opposite change trend. The expression of annexin A1 was confirmed using immunohistochemistry. The expression of superoxide dismutase (SOD) activity was confirmed biochemically. These results indicated that RuXian-I treats rat breast hyperplasia through regulation of cell cycle, immune system, metabolic, signal transduction, etc. The differential expressions of these proteins (annexin A1, superoxide dismutase [Mn], alpha B-crystallins and translationally controlled tumor protein, among others) were associated with occurrence and metastasis of breast cancer. These findings might provide not only far-reaching valuable insights into the mechanism of RuXian-I action, but also leads for prognosis and diagnosis of breast hyperplasia and breast cancer.     

CHANGES IN SUPEROXIDE DISMUTASE, CATALASE AND GLUCOSE-6-PHOSPHATE DEHYDROGENASE ACTIVITIES OF RABBIT ALVEOLAR MACROPHAGES: INDUCED BY POSTNATAL MATURATION AND/OR IN VITRO HYPEROXIA

Abstract— The total superoxide dismutase activity of rabbit alveolar macrophages (AM) increased twofold during the first postnatal week. This increase in superoxide dismutase activity was primarily mitochondrial and paralleled the increase in the number of mitochondria in these cells which has been previously reported. The superoxide dismutase activity of AM in culture for 18 h was significantly increased by hyperoxia; catalase activity in hyperoxic conditions was slightly adversely affected; glucose-6-phosphate dehydrogenase activity was increased but not significantly over control values. Hyperoxic cultures beyond 42 h decreased the total number of viable cells and the superoxide dismutase activity expressed per viable cell; the disappearance of catalase and glucose-6-phosphate dehydrogenase activities in this period, however, was more rapid in control alveolar macrophages than those under hyperoxia.     

Cytotoxic and antimicrobial aporphine alkaloids from Fissistigma poilanei (Annonaceae) collected in Vietnam

Two new aporphine alkaloids: 8-hydroxy-9-methoxy-1,2-methylenedioxyaporphine (1) and 8-hydroxy-3,9-dimethoxy-1,2-methylenedioxyaporphine (2) were isolated from the ethyl acetate extract of Fissistigma poilanei along with five known compounds: oxocrebanine (3), kuafumine (4), (2R,3R)-3',4',5,7-tetrahydroxydihydroflavonol-3-O-α-L-rhamnopyranoside (5), (+)-catechin 3-O-α-L-rhamnopyranoside (6) and quercetine 3,7-dimethoxy-3'-O-α-L-rhamnopyranosyl-(1?→?2)-β-D-glucopyranoside (7). These two new aporphine alkaloids exhibited a moderate cytotoxic activity against four human cancer cell lines (KB, Hep-G2, MCF-7, LU) as well as antimicrobial activity against Lactobacillus fermentum, Enterococcus faecium, Staphylococcus aureus and Bacillus subtillis.     

Preparation of Ag-MnFe2O4-bentonite Magnetic Composite for Pb(Ⅱ)/Cd(Ⅱ) Adsorption Removal and Bacterial Inactivation in Wastewater

An Ag-MnFe₂O₄-bentonite composite was synthesized by a chemical co-precipitation method and used for adsorption removal of Pb(Ⅱ), Cd(Ⅱ) and disinfection. The result of X-ray diffraction indicate that the diffraction peaks of MnFe₂O₄ and Ag can be perfectly indexed to the cubic spinel MnFe₂O₄(JCPDS No.88-1965) and metallic Ag(JCPDS No.41-1402), respectively. The results of scanning electron microscopy and energy dispersive X-ray spectroscopy manifest the deposition of MnFe₂O₄ and Ag on the bentonite surface and the presence of Mn, Fe and Ag. The result of X-ray photoelectron spectroscopy displayed that the composition of Ag-MnFe₂O₄-bentonite was Mn(Ⅱ), Fe(ⅡI) and metallic Ag. The analysis of Brunauer-Emmett-Teller showed that the specific surface area of Ag-MnFe₂O₄-bentonite was the largest compared with that of bentonite, MnFe₂O₄ and MnFe₂O₄-bentonite. Thermodynamic studies revealed that the adsorption of Pb(Ⅱ) and Cd(Ⅱ) ions was spontaneous and endothermic. Langmuir model showed an adsorption capacity of 129.87 mg/g for Pb(Ⅱ) and 48.31 mg/g for Cd(Ⅱ) ions. The adsorption kinetics of Pb(Ⅱ) and Cd(Ⅱ) ions onto Ag-MnFe₂O₄-bentonite can be best described by a pseudo-second-order model. The adsorption rate constant of the pseudo-second-order model was 0.0019 g·mg^-1·min^-1 for Pb(Ⅱ) and 0.0065 g·mg^-1·min^-1 for Cd(Ⅱ) ions. In addition to the adsorption experiment, the antibacterial properties of Ag-MnFe₂O₄-bentonite were studied through plate count method. Gram-negative(G-) bacteria Escherichia coli and Gram-positive(G+) bacteria Lactobacillus plantarum were used to test the antibacterial properties. The results showed that the composite demonstrated excellent antibacterial activity. Thus, Ag-MnFe₂O₄-bentonite can be employed as an adsorbent as well as an antimicrobial agent.     

Antioxidant and Hepatoprotective Activity of a Lichen Usnea ghattensis in Vitro

Antioxidative and hepatoprotective activity of a cultured lichen Usnea ghattensis has been studied. The methanolic extract of cultured lichen U. ghattensis showed good antioxidant activity by preventing lipid peroxidation by 67% and 86% in Trolox-equivalent antioxidant capacity at 20 microg/ml. It also showed superoxide, 1,1-diphenyl-2-picrylhydrazyl, nitric oxide, and hydroxyl radical-scavenging activity, 89%, 89.6%, 94.8%, and 89.6%, respectively, and found levels higher then that known for the synthetic antioxidants butylated hydroxytoluene, butylated hydroxyanisol, and quercetin at 20 microg/ml concentration. The cultured lichen extract also showed hepatoprotection against ethanol-induced toxicity in the mice liver slice culture model by a significant decrease in the antioxidant enzymes, glutathione peroxidase, catalase, and superoxide dismutase, along with a decrease in lipid peroxidation and lactate dehydrogenase release.     

二十员六氮大环双核铜（Ⅱ）配合物与超氧离子的反应

合成了以2,6-二乙酰基吡啶缩丙二胺为配体,以OH~-、Cl~-、Br~-、I~-、SCN~-及N_3~-为桥基的6种大环双核铜配合物,用光照法研究了这类配合物催化O_2~-的歧化反应的活性,通过顺磁共振波谱,探讨了各种桥基的配合物与O_2~-反应的两种反应机理:催化歧化机理及氧化还原机理。     

The Voltammetric Behavior of Superoxide Dismutase/Catalase Mimics

The voltammetric behavior of the superoxide dismutase/catalase mimics [(N,N′‐bis(salicylidene)ethylenediamine)Mn(III)]Cl (or salenMn(III) chloride) 1 and [(N,N′‐bis(3‐methoxysalicylidene)ethylenediamine)Mn(III)]Cl (or 3,3′‐methoxysalenMn(III) chloride) 2 in acetonitrile is described. Both compounds show quasi‐reversible one‐electron reductions to the Mn(II) compound. Electroanalytical techniques are used to follow the reaction between superoxide and 1 and 2 and it is shown that it is the reduced Mn(II) compounds which scavenge superoxide. It is also shown that both compounds electrocatalytically generate superoxide in the presence of dissolved dioxygen. The rate constant for this reaction was determined for both compounds using microelectrode steady state voltammetry. A general reaction scheme for interactions between these compounds and both dissolved dioxygen and superoxide is proposed.     

锰超氧化物歧化酶及其化学模拟研究

本文综述了近年来有关锰超氧化物歧化酶(MnSOD) 结构、活性部位、作用机理和模型化合物等的研究进展。     

Zinc deficient bovine erythrocyte superoxide dismutase has low specific activity.

Zinc deficient bovine superoxide dismutase (Cu2E2SOD (E = empty)) was prepared and purified by high performance liquid chromatography (HPLC). Each peak was characterized as to protein, copper content and specific activity. The Cu2E2SOD peak fractionated by HPLC has a low specific activity at pH 7.8 (about 10% of the native enzyme (Cu2Zn2SOD)). With the addition of zinc ions, the specific activity of Cu2E2SOD was quantitatively restored to that of the native enzyme. This behavior implies that the zinc ion is very important for the appearance of enzyme activity.     

Xanthine oxidase-assisted catalysis by dopamine β-hydroxylase: Mechanistic considerations on the role of superoxide anion

Dopamine β-monooxygenase catalyzes the transformation of dopamine into norepinephrine by inserting an O-atom on a benzylic C–H bond. The activation of O₂ occurs at a copper-containing active site in the presence of a reducer (ascorbate) that enables that copper ions be reduced to Cu(I) and reoxidized during catalysis. In the present paper, we establish that the xanthine/xanthine oxidase coupled system is a cofactor for this enzyme, and that hydroxylation of substrate tyramine is time-dependent. Using superoxide dismutase, we unambiguously prove that the species responsible for the hydroxylase activity is superoxide anion. The optimum pH for this activity is 6.8, a value about one pH unit higher than the physiological pH for the enzyme. Moreover, we propose a mechanism that takes into account all of our results, and describes putative interactions between the copper ions of the active site and superoxide anion.     

Antitumour activity of Prosopis cineraria (L.) Druce against Ehrlich ascites carcinoma-induced mice

The antitumour activity of the hydroalcoholic extract of the leaf (PCL) and stem bark (PCB) of Prosopis cineraria (L.) in Swiss albino mice was evaluated against an Ehrlich ascites carcinoma (EAC) tumour model. The activity was assessed using survival time, peritoneal cells, haematological studies, lipid peroxidation, antioxidant enzymes such as superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, solid tumour mass and in?vitro cytotoxicity. PCL and PCB were found to be potent and possessed significant cytotoxicity towards EAC tumour cells.     

Anti-lipid peroxidative effect of an extract of the stems of Kadsura heteroclita and its major constituent, kadsurin, in mice.

Three-days successive p.o. administration of an EtOH extract of the stems of Kadsura heteroclita (Schizandraceae) or its major constituent, kadsurin, resulted in significant decreases of CCl4-induced lipid-peroxidation products, such as thiobarbituric acid reactive substances (TBA-RS), conjugated dienes and fluorescent products in the liver of mice. In contrast, a significant restoration of superoxide dismutase (SOD) activity reduced by CCl4-intoxication was observed in the administered groups, suggesting that the subchronic treatment of mice with the EtOH extract or kadsurin induce enzymes capable of scavenging oxygen radical species in the liver, though the extract and kadsurin themselves may have an anti-oxidant property.     

Temperature-dependent coordination in E. coli manganese superoxide dismutase

Two different temperature dependences of the manganese(II) high-field electron paramagnetic resonance spectrum of manganese superoxide dismutase from E. coli were observed. In the 25-200 K range, the zero-field interaction steadily decreased with increasing temperature. This was likely due to the thermal expansion of the protein. From these results, it was possible to deduce an approximately r(-)(2.5) dependence of Mn(II) zero-field interaction on ligand-metal distance. At temperatures above 240 K, a distinct six-line component was detected, the amplitude of which decreased with increasing temperature. On the basis of similarities to the six-line spectrum observed for the azide-complexed E. coli manganese superoxide dismutase, the newly detected six-line spectrum was assigned to a hexacoordinate Mn(II) center resulting from the coordination of a nearby water molecule to the normally five-coordinate center. The changes in enthalpy and entropy characterizing the hexacoordinate-pentacoordinate equilibrium in the 240-268 K range were -5 kcal/mol and -24 cal/mol.K, respectively. The structural implications of the zero-field parameters of the newly found hexacoordinate form in comparison to those of the Mn(II) centers in concanavalin-A and manganese-containing R. spheroides photosynthetic reaction centers and the values predicted by the superposition model are discussed.