150 resultados para ABTS


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A new 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)-radical scavenging and antiproliferative agents of pyrrolo1,2-a]quinoline derivatives have been synthesized. An efficient method for the synthesis of 14 novel diversified pyrrolo1,2-a]quinoline derivatives has been described using 4-(1,3-dioxolan-2-yl)quinoline and different phenacyl bromides in acetone and followed by reacting with different acetylenes in dimethylformamide/K2CO3. The structure of the newly synthesized compounds was determined by infrared, H-1 NMR, C-13 NMR, mass spectrometry, and elemental analysis. The in vitro antioxidant activity revealed that among all the tested compounds 5n exhibited maximum scavenging activity with ABTS. Compound 5b has showed good antiproliferative activity as an inhibitor of epidermal growth factor receptor (EGFR) tyrosine kinase.

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A new solid composite polymer electrolyte was reported by incorporating Azino-bis-(3-ethyl benzo thiazoline-6-sulphonate) ion [ABTS] as dopant in poly(vinylidene flouride) along with redox couple (1-/13-). Under certain conditions, the electrolyte composition forms brush like nano-rods while it is doped with Azino-bis-(3-ethly) benzo thiazoline-6-sulphonate) ion [ABTS], a pi-electron donor. The polymer electrolyte forms nanoscale interpenetrating network with the crystalline order of the polymer electrolyte that seems to be a desirable architecture for the active layer of the photoelectrochemical cell. With this new polymer electrolyte, dye-sensitized solar cell was fabricated using N3 dye absorbed over Ti02- nonoparticles (photoanode) and conducting carbon cement coated on the conducting press (FTO, photocathode). This polymer composite has been successfully used as a promising candidate as solid polymer electrolyte in nanocrystalline dye-sensitized solar cell.

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Two monoclonal antibodies (mAb) CB268 and CII-C1 to type II collagen (CII) react with precisely the same conformational epitope constituted by the residues ARGLT on the three chains of the CII triple helix. The antibodies share structural similarity, with most differences in the complementarity determining region 3 of the heavy chain (HCDR3). The fine reactivity of these mAbs was investigated by screening two nonameric phage-displayed random peptide libraries. For each mAb, there were phage clones (phagotopes) that reacted strongly by ELISA only with the selecting mAb, and inhibited binding to CII only for that mAb, not the alternate mAb. Nonetheless, a synthetic peptide RRLPFGSQM corresponding to an insert from a highly reactive CII-C1-selected phagotope, which was unreactive (and non-inhibitory) with CB268, inhibited the reactivity of CB268 with CII. Most phage-displayed peptides contained a motif in the first part of the molecule that consisted of two basic residues adjacent to at least one hydrophobic residue (e.g. RRL or LRR), but the second portion of the peptides differed for the two mAbs. We predict that conserved CDR sequences interact with the basic-basic-hydrophobic motif, whereas non-conserved amino acids in the binding sites (especially HCDR3) interact with unique peptide sequences and limit cross-reactivity. The observation that two mAbs can react identically with a single epitope on one antigen (CII), but show no cross-reactivity when tested against a second (phagotope) indicates that microorganisms could exhibit mimics capable of initiating autoimmunity without this being evident from conventional assays.

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Bound photocopies of various documents, describing the estate of Solomon Abt in the town of Melsungen in Hesse, Germany. Included are the copies of a marriage contract between Solomon Abt and Vogel Tebler; extensive lists of all of Solomon Abt’s possession when he died in 1829; correspondence of his heirs and the guardians of his children, as well as various court documents.

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对15株白腐真菌进行了以玉米秸秆为基质的初步筛选,从中获得一株选择性系数较高的菌株Y10,并对其降解玉米秸秆的情况进行了研究。结果表明,在30天的培养过程中菌株Y10对玉米秸秆降解的选择性系数都大于1,第15天选择性系数最高为3.88。对未经降解和降解过的玉米秸秆分别作了紫外光谱和红外光谱分析,结果表明,经该菌降解后玉米秸秆的化学成分发生了很大变化,且木质素的降解程度要大于纤维素的降解程度。对菌株Y10进行了ITS-5.8S rDNA序列鉴定,初步判定其为Cerrena sp.。 为了考查不同的外源添加物对菌株Y10降解玉米秸秆的影响,在以玉米秸秆为基质的固态发酵培养基中分别添加了7种金属离子、8种碳源、6种氮源。结果显示,这7种金属离子均能促进木质素的降解,并且一定浓度的某些离子明显抑制纤维素的降解;其中添加0.036%的MnSO4·H2O和0.36%的MgSO4·7H2O对纤维素降解的抑制作用比较强,降解率分别为0.96%和1.31%,木质素的选择性系数分别达到了34.40和20.17。8种碳源中除麦芽糖外都能促进木质素的降解,除微晶纤维素外都明显促进纤维素的降解。6种氮源中酒石酸铵、硫酸铵、草酸铵和氯化铵的添加都会使该菌生长变慢,而且氮源浓度越高菌丝生长越慢。外加碳源和金属离子对半纤维素降解和选择性系数的影响不大。 同时对菌株Y10在液态培养下产木质素降解酶的条件和培养基做了优化。结果表明,在初始产酶培养基中,菌株Y10的漆酶酶活在第10d达到最高,锰过氧化物酶酶活在第11d达到最高,基本上检测不到木质素过氧化物酶。菌株Y10产漆酶的最适温度为32℃,最适PH为6.0;产锰过氧化物酶的最适温度为32℃,最适PH为6.5。菌株Y10产漆酶的最佳碳源为甘露糖,最佳氮源为酒石酸铵,最适诱导剂VA浓度为3 mmol/L,最适表面活性剂TW-80浓度为1%。 利用响应面法对其产漆酶的培养基进行优化,优化后的培养基配方为葡萄糖10.00 g/L,酒石酸铵0.50 g/L,大量元素296.50 ml/L,微量元素100.00 ml/L,NTA 1.40 g/L,VA 5.00 mmol/L,吐温-80加入量为0.10%。进行了菌株Y10产漆酶的验证实验,实测酶活为5282.56 U/L,与预测酶活5162.73 U/L接近。在优化后培养基中,菌株Y10在第14 d达到生长的最高峰,第20 d时,漆酶酶活最高,为11325.00 U/L;第16 d时,锰过氧化物酶酶活最高,为30.77 U/L。 对菌株Y10的漆酶酶学性质做了初步的研究,结果显示,酶反应的最适温度为40℃-65℃,最适PH为3.0。在40℃,PH=3.0时,漆酶催化ABTS反应的米氏方程为 。 Fifteen white-rot fungi based on corn stalk were screened. One white-rot fungus Y10 with high selectivity value was obtained. The degradation of corn stalk was initially studied. The results indicated that the selectivity value was above 1 during the 30 day-cultivation and the highest was 3.88 after 15 days. The composition of untreated and treated stalk was analyzed through ultraviolet spectroscopy and infrared spectroscopy. It was found that the composition of treated stalk was greatly altered and the degree of the degradation of lignin is greater than the cellulose. Y10 was identified as Cerrena sp. by ITS -5.8S rDNA sequence analysis. The influence of metal ions, carbon sources and nitrogen sources on corn stalk degradation by white-rot fungus was studied. While all seven metal ions could promote lignin degradation, the cellulose degradation was best inhibited at certain ion concentrations. Notably, when 0.036% MnSO4·H2O and 0.36% MgSO4·7H2O were added into the medium, the cellulose degradation was restrained to the extents that the coefficients of lignin selectivity rose to 34.40 and 20.17 respectively. It was also found that all carbon sources except maltose can promote lignin degradation. The addition of carbon sources other than microcrystalline cellulose significantly promoted cellulose degradation. The addition of the nitrogen sources, ammonium tartrate, ammonium sulfate, oxalate, ammonium chloride, resulted in remarkable inhibition to mycelium growth; the larger the concentrations of nitrogen sources are, the slower the mycelium grew. The addition of carbon sources and metal ions had less impact on the degradation of hemicellulose and selectivity value. Meanwhile, we optimized the conditions and culture medium of the lignin-degrading enzyme production of strain Y10. The results showed that in the initial culture medium, the Lac activity was highest at the 10th day, the MnP activity was highest at the 11th day and the LiP could not be detected. The optimum condition of Lac was at temperature 32 and PH =6.0 and the optimum condition of MnP was at temperature 32 and PH =6.5. The optimum carbon source for Lac was seminose, the optimum nitrogen source was ammonium tartrate, the optimum content of VA was 3 mmol/L, the optimum content of TW-80 was 1%. PB and RSM were used to optimize the culture medium of laccase by white-rot fungus Y10. The optimum culture medium was consist of glucose 10.00 g/L, ammonium tartrate 0.50 g/L, macro elements 296.50 ml/L, trace elements 100.00 ml/L, NTA 1.40 g/L, VA 5.00 mmol/L, TW-80 0.10%. Under the optimal conditions, the activity of laccase was 5282.56 U/L and the experimental value agreed with the predicted value 5162.73 U/L. The biomass was highest at the 14th day, the Lac activity was highest at the 20th day, the MnP activity was highest at the 16th day. The results of the studies on the characteristics of Lac showed that the optimum temperature for Lac activity is 40℃-65℃ ; the optimum PH for Lac activity is 3.0 and under 40℃,PH=3.0, the Michaelis-menten equation of Lac catalized ABTS oxidation was .

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Due to the potentially adverse effects of the chromium (VI) on the human health and also on the environment, the quantitative determination of Cr(VI) is of particular interest. This work herein reports a facile, selective and rapid colorimetric determination of Cr(VI) based on the peroxidase substrate-2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) diammonium salt (ABTS) as the color developing agent. ABTS, which was usually acted as peroxidase substrate for the enzyme linked immunosorbent assay, is used here for the first time to fabricate the "signal-on" colorimetric Assay for Cr(VI).

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Mercury ion (Hg2+) is able to specifically bind to the thymine-thymine (T-T) base pair in a DNA duplex, thus providing a rationale for DNA-based selective detection of Hg2+ with various means. In this work, we for the first time utilize the Hg2+-mediated T-T base pair to modulate the proper folding of G-quadruplex DNAs and inhibit the DNAzyme activity, thereby pioneering a facile approach to sense Hg2+ with colorimetry. Two bimolecular DNA G-quadruplexes containing many T residues are adopted here, which function well in low- and high-salt conditions, respectively. These G-quadruplex DNAs are able to bind hemin to form the peroxidase-like DNAzymes in the folded state. Upon addition of Hg2+, the proper folding of G-quadruplex DNAs is inhibited due to the formation of T-Hg2+-T complex. Ibis is reflected by the notable change of the Soret band of hemin when investigated by using UV-vis absorption spectroscopy. As a result of Hg2+ inhibition, a sharp decrease in the catalytic activity toward the H2O2-mediated oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) is observed, accompanied by a change in solution color. Through this approach, aqueous Hg2+ can be detected at 50 nM (10 ppb) with colorimetry in a facile way, with high selectivity against other metal ions.

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The carbon nanotubes-chitosan (CNTs-CS) composite provides a suitable biosensing matrix due to its good conductivity, high stability, and good biocompatibility. Enzymes can be firmly incorporated into the matrix without the aid of other cross-linking reagents. The composite is easy to form insoluble film in solution above pH 6.3. Based on this, a facilely fabricated amperometric biosensor by entrapping laccase into the CNTs-CS composite film has been developed. At pH 6.0, the fungi laccase incorporated into the composite film remains better catalytic activity than that dissolved in solution. The system is in favor of the accessibility of substrate to the active site of laccase, thus the affinity to substrates is improved greatly, such as 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS), catechol, and 0, with K. values of 19.86 mu M, 9.43 mu M, and 3.22 mM, respectively. The major advantages of the as-prepared biosensor are: detecting different substrates (ABTS, catechol, and 02), possessing high affinity and sensitivity, durable long-term stability, and facile preparation procedure. On the other hand, the system can be applied in fabrication of biofuel cells as the cathodic catalysts based on its good electrocatalysis for oxygen reduction.

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海洋生物具有产生丰富多样的次生代谢产物的能力,其中红藻门松节藻科海藻卤代次生代谢产物以其结构新颖、生物活性独特引起了天然产物化学家的重视。 本论文对海洋红藻多管藻和松节藻进行了化学成分研究,综合利用各种色谱学方法 (硅胶柱层析、反相硅胶柱层析、凝胶Sephadex LH-20柱层析、半制备高效液相色谱以及重结晶等) 和现代波谱学技术 (IR、UV、EI-MS、FAB-MS、HR-ESI-MS、CD、1H-NMR、13C-NMR、DEPT、1H-1H COSY、HSQC、HMBC等),共分离鉴定了100个化合物,发现25个新化合物。 从多管藻中分离鉴定38个化合物 (24个溴酚化合物),其中7个新化合物 (均为溴酚化合物),包括1个菲并呋喃结构溴酚 (P1), 2个二氢菲结构溴酚 (P2, P3),1个含 5,7-dihydrodibenzo[c,e]oxepine 结构溴酚 (P4)和3个简单溴酚 (P5, P6, P7)。P1 (urceolatin) 属首例报道的具有菲并呋喃结构的天然产物,从该种中分离的化合物P12 和 P13 可能是其生源合成的前体。P2和P3为第二例报道的具有二氢菲结构的溴酚化合物。 从松节藻中分离并鉴定了62 个化合物,其中18 个为溴酚类新化合物,44 个为已知化合物。化合物具有多变的取代基团,包括2 个脲基吡咯烷酮溴酚化合物 (R1, R2), 4 个γ-脲基丁酸溴酚化合物 (R3-R6),5 个酰胺溴酚化合物 (R7, R8, R9, R13, R14),1 个溴酚砜化合物 (R12), 1 个Xanthene 溴酚化合物 (R10)和5 个简单溴酚化合物 (R11, R15, R16, R17, R18)。R1、R2 是首例报道的含有脲基吡咯烷酮片段的天然产物,R10 为首次报道的溴代Xanthene 类天然产物。 对分离到的化合物进行了清除DPPH 和ABTS两种自由基活性的筛选。结果发现溴酚类天然产物具有显著的DPPH自由基清除活性,其中R3 的IC50 仅为3.3 μM, 其活性强度约为阳性对照BHT (IC50 为82.1 μM) 的24倍。另外,溴酚类天然产物对ABTS自由基有较强的清除活性,R2 的TEAC(Trolox efficency activity capacity)值为5.2 mM,约为阳性对照 (ascorbic acid, 1.02 mM) 的 5 倍。初步的构效关系研究发现,稠环分子、多羟基和邻位甲氧基等结构特点能有效增强DPPH 自由基清除活性;特殊取代基如脲基、吡咯烷酮等含有氮原子的基团,能有效增强ABTS 自由基清除活性,多羟基、溴代等结构特点也使其活性有所增强。 本研究结果丰富了海藻卤代化合物的结构类型,为多管藻和松节藻的合理利用提供了一定的科学依据。

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Green malt was kilned at 95 degrees C following two regimens: a standard regimen (SKR) and a rapid regimen (RKR). Both resulting malts were treated further in a tray dryer heated to 120 degrees C, as was green malt previously dried to 65 degrees C (TDR). Each regimen was monitored by determining the color, antioxidant activity (by both ABTS(center dot+) and FRAP methods), and polyphenolic profile. SKR and RKR malts exhibited decreased L* and increased b* values above approximately 80 degrees C. TDR malts changed significantly less, and color did not develop until 110 degrees C, implying that different chemical reactions lead to color in those malts. Antioxidant activity increased progressively with each regimen, although with TDR malts this became significant only at 110-120 degrees C. The RKR malt ABTS(center dot+) values were higher than those of the SKR malt. The main phenolics, that is, ferulic, p-coumaric, and vanillic acids, were monitored throughout heating. Ferulic acid levels increased upon heating to 80 degrees C for SKR and to 70 degrees C for RKR, with subsequent decreases. However, the levels for TDR malts did not increase significantly. The increase in free phenolics early in kilning could be due to enzymatic release of bound phenolics and/or easier extractability due to changes in the matrix. The differences between the kilning regimens used suggest that further modification of the regimens could lead to greater release of bound phenolics with consequent beneficial effects on flavor stability in beer and, more generally, on human health.

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Samples were taken at each stage of brewing (malt, milling, mashing, wort separation, hop addition, boiling, whirlpool, dilution, fermentation, warm rest, chill-lagering, beer filtration, carbonation and bottling, pasteurization, and storage). The level of antioxidant activity of unfractionated, low-molecular-mass (LMM) and high-molecular-mass (HMM) fractions was measured by the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfortic acid) radical cation (ABTS(.+)) and ferric-reducing antioxidant power (FRAP) procedures. Polyphenol levels were assessed by HPLC. The LMM fraction ( 0.001) in catechin and ferulic acid levels. Increases in antioxidant activity levels were observed after mashing, boiling, fermentation, chill-lagering, and pasteurization, in line with previous studies on lager. Additionally, increases in the level of antioxidant activity occurred after wort separation and carbonation and bottling and were accompanied by increases in levels of most monitored polyphenols. Data from the ABTS(.-) and FRAP assays indicated that the compounds contributing to the levels of antioxidant activity responded differently in the two procedures. Levels of ferulic, vanillic, and chlorogenic acids and catechin accounted for 45-61% of the variation in antioxidant activity levels.

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Colombian Arabica coffee beans were roasted to give light, medium, and dark samples. Their aqueous extracts were analyzed by gel filtration chromatography, UV-visible spectrophotometry, capillary electrophoresis, and the ABTS(.+) assay. A progressive decrease in antioxidant activity (associated mainly with chlorogenic acids in the green beans) with degree of roasting was observed with the simultaneous generation of high (HMM) and low molecular mass (LMM) compounds possessing antioxidant activity. Maximum antioxidant activity was observed for the medium-roasted coffee; the dark coffee had a lower antioxidant activity despite the increase in color. Analysis of the gel filtration chromatography fractions showed that the LMM fraction made a greater contribution to total antioxidant activity than the HMM components.