2-2--azino-di-(3-ethylbenzothiazoline)-6-sulfonic-acid and catechol

Glutinous rice-based foods have a long history are consumed worldwide. They are also in great demand for the pursuit of novel sensory and natural health benefits. In this study, we developed a novel fermented glutinous rice product with the supplementation of Fu brick tea. Using in vitro antioxidant evaluation and phenolic compounds analysis, fermentation with Fu brick tea increased the total phenolic content and enhanced the antioxidant activity of glutinous rice, including scavenging of 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) radical, 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical, and hydroxyl radical, ferric-reducing antioxidant power, and ferric ion reducing power and iron chelating capability. Besides, compared with traditional fermented glutinous rice, this novel functional food exhibited a stronger activity for protecting DNA against hydroxyl radical-induced oxidation damage. Quantitative analysis by HPLC identified 14 compounds covering catechins and phenolic acids, which were considered to be positively related to the enhanced antioxidant capability. Furthermore, we found that 80% ethanol was a suitable extract solvent compared with water, because of its higher extraction efficiency and stronger functional activities. Our results suggested that this novel fermented glutinous rice could serve as a nutraceutical food/ingredient with special sensory and functional activities.

Topics: Antioxidants; Benzothiazoles; Biphenyl Compounds; Catechols; China; Chromatography, High Pressure Liquid; DNA Damage; Fermentation; Free Radical Scavengers; Humans; Hydroxyl Radical; Iron Chelating Agents; Oryza; Oxidation-Reduction; Phenols; Picrates; Sulfonic Acids; Triterpenes

The aim of this study was to evaluate the activity of a novel bacterial laccase-like multi-copper oxidase (LMCO) from Paenibacillus glucanolyticus SLM1: a bacterium isolated from pulp and paper waste.. A new bacterial LMCO gene (CuOx) from P. glucanolyticus SLM1 was identified and cloned into pET22b. The protein it encodes was recombinantly expressed in Escherichia coli. The recombinant P. glucanolyticus LMCO had a molecular weight of approximately 90 kDa and demonstrated oxidation of the LMCO substrates 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS), catechol, and 2,6-Dimethoxyphenol (2,6-DMP), with the oxidation of ABTS occurring to the greatest extent (776 U mg. This enzyme has a neutral pH optimum, is capable of decolorizing dyes, and is active in the presence salt, detergents and surfactant. The characteristics of this enzyme suggest that it could be used for a variety of industrial applications.. This work characterizes a unique bacterial LMCO with activity higher than that of previously characterized fungal or bacterial LMCOs. This enzyme may have utility for industrial bleaching, treatment of dye effluent, and lignin removal.

Topics: Benzothiazoles; Catechols; Coloring Agents; Hydrogen-Ion Concentration; Oxidoreductases; Paenibacillus; Pyrogallol; Recombinant Proteins; Sulfonic Acids

Carbon nanoparticles are promising candidates for enzyme immobilization. We investigated enzyme loading and laccase activity on various carbon nanoparticles, fullerene (C60), multi-walled carbon nanotubes (MWNTs), oxidized-MWNTs (O-MWNTs), and graphene oxide (GO). The loading capacity was highest for O-MWNTs and lowest for C60. The activity of laccase on various nanomatrices using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTs) as a substrate decreased in the following order: GO>MWNTs>O-MWNTs>C60. We speculated that aggregation of the nanoparticles influenced enzyme loading and activity by reducing the available adsorption space and substrate accessibility. The nanoparticle-immobilized laccase was then used for removal of bisphenol and catechol substrates. Compared to free laccase, the immobilized enzymes had significantly reduced reaction rates. For example, the reaction rate of GO-laccase conjugated with bisphenol or catechol substrates was only 10.28% or 12.33%, respectively, of that of the free enzyme. Considering that there was no obvious structural change observed after enzyme immobilization, nanomatrix-induced diffusional limitation most likely caused the low reaction rates. These results demonstrate that the diffusional limitation induced by the aggregation of carbon nanoparticles cannot be ignored because it can lead to increased reaction times, low efficiency, and high economic costs. Furthermore, this problem is exacerbated when low concentrations of environmental contaminants are used.

Topics: Benzhydryl Compounds; Benzothiazoles; Biodegradation, Environmental; Carbon; Catechols; Diffusion; Enzymes, Immobilized; Fullerenes; Graphite; Hydrogen-Ion Concentration; Laccase; Nanostructures; Nanotubes, Carbon; Oxidation-Reduction; Phenols; Sulfonic Acids

Coptotermes formosanus Shiraki is a well-known wood-feeding termite, which can degrade not only cellulose and hemicellulose polysaccharides, but also some aromatic lignin polymers with its enzyme complex to the woody biomass. In this study, a very abundant protein was discovered and purified, using a three-step column chromatography procedure, from the tissue homogenate of the salivary glands and the gut of C. formosanus. Mass spectrometric analysis and the following peptide searching against the mRNA database toward this termite species indicated that the novel protein was a hemocyanin enzyme, termed as Hemo1, which further exhibited a strong oxidase activity in the substrate bioassays toward ABTS [2,2'-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)], as well as other aromatic analogues, such as catechol and veratryl alcohols. This oxidative protein was an acid-favored enzyme with a molecular weight at 82 kDa, and highly active at 80 °C. These findings indicated that the novel protein, hemocyanin, discovered from the gut system of C. formosanus, might be an important ligninolytic enzyme involved in the biomass pretreatment processing, which will potentially enhance the digestibility and utilization of biomass polysaccharides in termite digestive systems.

Topics: Amino Acid Sequence; Animals; Benzothiazoles; Benzyl Alcohols; Catechols; Enzyme Stability; Gastrointestinal Tract; Hemocyanins; Hot Temperature; Insect Proteins; Isoptera; Kinetics; Lignin; Molecular Sequence Data; Molecular Weight; Oxidoreductases; Peptide Mapping; Salivary Glands; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Substrate Specificity; Sulfonic Acids; Wood

A large panel of novel catecholic antioxidants and their fatty acid or methyl carbonate esters has been synthesized in satisfactory to good yields through a 2-iodoxybenzoic acid (IBX)-mediated aromatic hydroxylation as the key step. The new catechols are structural analogues of naturally occurring hydroxytyrosol (3,4-DHE). To evaluate structure/activity relationships, the antioxidant properties of all catecholic compounds were evaluated in vitro by ABTS assay and on whole cells by DCF fluorometric assay and compared with that of the corresponding already known hydroxytyrosyl derivatives. Results outline that all of the new catechols show antioxidant capacity in vitro higher than that of the corresponding hydroxytyrosyl derivatives. Less evident positive effects have been detected in whole cells experiments. Cytotoxicity experiments, using MTT assay, on a representative set of compounds evidenced no influence in cell survival.

Topics: Animals; Antioxidants; Benzothiazoles; Catechols; Cell Line; Cell Survival; Esters; Fatty Acids; Iodobenzenes; Iodobenzoates; Myoblasts; Phenylethyl Alcohol; Rats; Structure-Activity Relationship; Sulfonic Acids

The present paper reports on the diffusion characteristics and electron transfer properties of a membrane obtained from polyazetidine prepolymer (PAP) consisting of repeating units of 1-(aminomethyl)-1-{2-[(6-oxyhexane)amino]ethyl}-3-hydroxyazetidinium chloride studied in the presence of seven simple redox electroactive molecules: ABTS, catechol, dopamine, ferrocenecarboxylic acid, ferricyanide, ferrocyanide, and the osmium complex bis(2,2-bipyridyl)-4-aminomethylpyridine chloride hexafluorophosphate (Os[(bpy)(2) 4-AMP Cl](+)). Using water as medium, the apparent diffusion coefficients (D(app)), the concentrations of the compounds in the membrane, and the heterogeneous rate constants (k(s)) were calculated as a function of temperature, and the influence thereof on these parameters was evaluated. Even if D(app) and k(s) values in the presence of PAP are smaller than in solution, this decrease is small enough to indicate that the PAP membrane shows excellent diffusion and electron-exchange properties with respect to other commonly used membranes reported in the literature.

Topics: Azetidines; Benzothiazoles; Catechols; Diffusion; Dopamine; Electrochemical Techniques; Electron Transport; Ferricyanides; Ferrocyanides; Microelectrodes; Oxidation-Reduction; Polymers; Sulfonic Acids; Temperature

A major laccase isozyme (Lac 1) was isolated from the culture fluid of an edible basidiomycetous mushroom, Grifola frondosa. Lac 1 was revealed to be a monomeric protein with a molecular mass of 71 kDa. The N-terminal amino acid sequence of Lac 1 was highly similar to those of laccases of some other white-rot basidiomycetes. Lac 1 showed the typical absorption spectrum of a copper-containing enzyme. The enzyme was stable in a wide pH range (4.0 to 10.0), and lost no activity up to 60 °C for 60 min. The optimal pH of the enzyme activity varied among substrates. The K(m) values of Lac 1 toward 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), 2,6-dimethoxyphenol, guaiacol, catechol, and 3,4-dihydroxy-L-phenylalanine were 0.0137 mM, 0.608 mM, 0.531 mM, 2.51 mM, and 0.149 mM respectively. Lac 1 activity was remarkably inhibited by the chloride ion, in a reversible manner. Lac 1 activity was also inhibited by thiol compounds.

Topics: Amino Acid Sequence; Benzothiazoles; Catechols; Chlorides; Copper; Dopamine; Enzyme Stability; Fungal Proteins; Grifola; Guaiacol; Hydrogen-Ion Concentration; Kinetics; Laccase; Lignin; Molecular Sequence Data; Molecular Weight; Pyrogallol; Substrate Specificity; Sulfhydryl Compounds; Sulfonic Acids

The demand for novel effective antioxidant-based drugs has led to the synthesis and evaluation of the antioxidant potential in several molecules derived from natural compounds. In this work the in vitro antioxidant activity of an abietic acid-derived catechol (methyl 11,12-dihydroxyabietate-8,11,13-trien-18-oate, MDTO) was evaluated. This substance, possessing important biological properties, is similar to carnosic acid, a natural antioxidant from rosemary or sage leaves. Aiming to understand the antioxidant activity of MDTO, the energetics of its O-H bond, using time-resolved photoacoustic calorimetry (TR-PAC), was investigated. On energetic grounds it is predicted that MDTO is a good free radical scavenger, although its activity is lower than that of quercetin, a very effective antioxidant, which was used for comparison. In agreement with these predictions, the DPPH(*) and ABTS(*+) radical scavenging activities are lower than those of quercetin. In addition, MDTO also reacts with HOCl, a powerful proinflammatory oxidant produced by activated neutrophils, and protects liposomes against iron-ascorbate-induced oxidation. The discussion of these results foresees potential applications of MDTO as an antioxidant.

Topics: Abietanes; Antioxidants; Benzothiazoles; Biphenyl Compounds; Calorimetry; Catechols; Free Radical Scavengers; Lipid Peroxidation; Liposomes; Phenanthrenes; Picrates; Sulfonic Acids; Thermodynamics

The activity and composition of leafhopper saliva are important in interactions with the host rice plant, and it may play a physiological role in detoxifying toxic plant substances or ingesting sap. We have characterized diphenoloxidase in the salivary glands of Nephotettix cincticeps, its activity as a laccase, and its presence in the watery saliva with the objective of understanding its function in feeding on rice plants. Nonreducing SDS-PAGE of salivary gland homogenates with staining by the typical laccase substrate 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), hydroquinone or syringaldazine revealed a band at a molecular mass of approximately 85 kDa at pH 5. A band also appeared at a molecular mass of approximately 200 kDa when the gels were treated with dopamine, L-3,4-dihydroxyphenylalanine (DOPA) or catechol at pH 7. The ABTS-oxidizing activity of the homogenates was drastically inhibited by N-hydroxyglycine, a specific inhibitor of laccase. However, the dopamine-oxidizing activity was not inhibited by N-hydroxyglycine, while it was inhibited by phenylthiourea (PTU). Thus, the salivary glands of N. cincticeps contain two types of phenoloxidases: a laccase (85 kDa) and a phenoloxidase (200 kDa). Laccase activity was detected in a holidic sucrose diet that was fed on for 16 h by two females, but only a trace of catechol oxidase activity was observed, suggesting that the laccase-type phenoloxidase was the predominant phenoloxidase secreted in watery saliva. The laccase exhibited an optimum pH of 4.75-5 in McIlvaine buffer and had a PI of 4.8. Enzyme activity was histochemically localized in V cells of the posterior lobe of the salivary glands. It remained at the same level throughout the adult stage from 2 days after eclosion. A possible function of N. cincticeps salivary laccase may be rapid oxidization of potentially toxic monolignols to nontoxic polymers during feeding on the rice plant. This is the first report proving that laccase occurs in the salivary glands of Hemiptera species and is secreted in the watery saliva.

Topics: Animals; Benzothiazoles; Catechol Oxidase; Catechols; Dihydroxyphenylalanine; Dopamine; Electrophoresis, Polyacrylamide Gel; Hemiptera; Histological Techniques; Hydrazones; Hydrogen-Ion Concentration; Hydroquinones; Laccase; Oxidation-Reduction; Salivary Glands; Salivary Proteins and Peptides; Sulfonic Acids