tannins and catechol

Topics: Adhesives; Biofouling; Catechols; Clay; Electrodes; Hydrogels; Polymers; Tannins

Iron ligands as 1,2-dihydroxybenzenes (1,2-DHBs) have been used to increase the oxidizing ability of Fenton systems. However, these kinds of ligands become toxic quinones in the process creating an environmental problem since these compounds cannot be easily separated from a solution. To avoid this problem, in the present work, water-insoluble tannins, obtained from Pinus radiata bark, were used as a source of 1,2-DHBs to promote the oxidizing ability of the Fenton process. The developed system was tested using atrazine, as a substrate, which is a toxic and recalcitrant compound, present in different sources of water. The best reaction conditions established by the experimental design were as follows: pH of 3.6; 2.4 mmol L

Topics: Atrazine; Catechols; Environmental Pollutants; Herbicides; Hydrogen Peroxide; Iron; Pinus; Plant Bark; Tannins

Novel soybean meal-based biomimetic (STP) adhesives were fabricated via soybean meal (SM) and enhanced by tannic acid (TA) and polyetheylenimine (PEI) (TAPI) co-crosslinking network based on natural polyphenol-inspired chemistry. The multiple physico-chemical interactions (including intermolecular H-bonding and covalent bonding) between the TAPI co-crosslinking system and SM matrices were examined by the Fourier transform infrared spectroscopy, solid-state

Topics: Adhesives; Catechols; Chemical Phenomena; Magnetic Resonance Spectroscopy; Microscopy, Electron, Scanning; Polyethyleneimine; Protein Binding; Soybean Proteins; Spectroscopy, Fourier Transform Infrared; Tannins; Thermogravimetry; X-Ray Diffraction

Nanoparticles based on hyaluronic acid (HA) are designed to deliver tannic acid (TA) as an antimicrobial agent. The presence of HA makes these particles potentially useful to target bacteria that colonize cells presenting HA membrane receptors (e.g. CD44), such as macrophages. HA bearing 3-aminophenyl boronic acid groups (HA-APBA) is reacted with TA, yielding nanoparticles with a size that decreases with decreasing HA molecular weight (e.g. 200 nm for 44 kDa, 400 nm for 737 kDa). The boronate esters make the nanoparticles stable at physiological pH, but their hydrolysis in an acidic environment (pH = 5) leads to swelling/solubilization, therefore potentially allowing TA release in endosomal compartments. We have assessed the nanoparticle toxicity profile (on RAW 264.7 macrophages) and their antimicrobial activity (on E. coli and on both methicillin-sensitive and -resistant S. aureus). The antibacterial effect of HA-APBA/TA nanoparticles was significantly higher than that of TA alone, and has very similar activity to TA coformulated with a reducing agent (ascorbic acid), which indicates both the nanoparticles to protect TA catechols from oxidation, and the effective release of TA after nanoparticle internalization. Therefore, there is potential for these nanoparticles to be used in stable, effective, and potentially targetable nanoparticle-based antimicrobial formulations.

Topics: Animals; Anti-Bacterial Agents; Boronic Acids; Catechols; Cell Survival; Cells, Cultured; Drug Carriers; Escherichia coli; Hyaluronic Acid; Macrophages; Methicillin-Resistant Staphylococcus aureus; Mice; Nanoparticles; RAW 264.7 Cells; Staphylococcus aureus; Tannins

Multifrequency EPR spectroscopy and DFT calculations were used to investigate Hg(II) complexes with semiquinone radical ligands formed in a direct reaction between the metal ions and tannic acid (a polyphenol closely related to tannins). Because of the intricate structure of tannic acid a vast array of substituted phenolic compounds were tested to find a structural model mimicking its ability to react with Hg(II) ions. The components of the g matrix (the g tensor) determined from the high field (208 GHz) EPR spectra of the Hg(II) complexes with the radical ligands derived from tannic acid and from the model compounds were analogous, indicating a similar coordination mode in all the studied Hg(II) complexes. Since catechol (1,2-dihydroxybenzene) was the simplest compound undergoing the reaction with Hg(II) it was selected for DFT studies which were aimed at providing an insight into the structural properties of the investigated complexes. Various coordination numbers and different conformations and protonation states of the ligands were included in the theoretical analyses. g Matrices were computed for all the DFT optimized geometries. A good agreement between the theoretical and experimental values was observed only for the model with the Hg(II) ion tetracoordinated by two ligands, one of the ligands being monoprotonated with the unpaired electron mainly localized on it.

Topics: Benzoquinones; Catechols; Electron Spin Resonance Spectroscopy; Fourier Analysis; Ligands; Macromolecular Substances; Mercury Compounds; Phenols; Tannins

Tyrosinase inhibitors have been used as whitening or antihyperpigment agents because of their ability to suppress dermal-melanin production. In the present study, screening and kinetic evaluation of various small molecules were performed on mushroom tyrosinase (MT) using surface plasmon resonance. The binding constant KD (M) values obtained for tannic acid, phloroglucinol, saffron, catechol, and pyrogallol are 1.213 × 10(-4), 7.136 × 10(-5), 3.111 × 10(-5), 1.557 × 10(-5), and 7.981 × 10(-6) M, respectively. Pyrogallol has been found to display high affinity for MT, whereas catechol, saffron, and phloroglucinol have been found to bind with low affinity. MT shows considerable changes in the secondary structure in the presence of inhibitors. The study reveals the Biacore/SPR sensor's ability in the rapid identification and characterization of inhibitors for MT. The methodology described here can be used to rapidly screen and optimize various lead compounds for other enzymes and elucidate structure function inter-relationships between various enzymes.

Topics: Agaricales; Biosensing Techniques; Catechols; Circular Dichroism; Crocus; Enzyme Inhibitors; Melanins; Monophenol Monooxygenase; Phloroglucinol; Pyrogallol; Surface Plasmon Resonance; Tannins

'Tar bush' and 'creosote bush' were substrates of fungal cultivation for tannase production and gallic acid and pyrocatechol accumulation. Aspergillus niger GH1 grew similarly on both plant materials under solid state culture conditions, reaching maximal levels after 4 d. Fungal strain degraded all tannin content of creosote bush after 4 d of fermentation and >75 % of tar bush after 5 d. Higher level of tannase activity was detected in tar bush fermentation. Biotransformation of tannins to gallic acid was high (93 % in creosote bush and 89 % in tar bush). Pyrocatechol was released poorly. Kinetic parameters of tannin conversion were calculated.

Topics: Aspergillus niger; Asteraceae; Biotransformation; Carboxylic Ester Hydrolases; Catechols; Cell Culture Techniques; Culture Media; Gallic Acid; Industrial Microbiology; Kinetics; Larrea; Plant Leaves; Tannins

Topics: Biomedical Research; Blood Coagulation Factors; Catechols; Dihydroxyphenylalanine; Dopamine; Ellagic Acid; Factor VII Deficiency; Factor XII; Flavonoids; Gallic Acid; Hemophilia A; Hemophilia B; Humans; Lactones; Pharmacology; Prothrombin; Pyrogallol; Research; Serum Globulins; Tannins; Thrombin; Thromboplastin

The effect of aqueous extracts of carob (Ceratonia siliqua) pods, gallotannic acid, gallic acid, and catechol on several microorganisms was studied. Carob pod extract and tannic acid showed a strong antimicrobial activity toward some cellulolytic bacteria. On the basis of tannin content, to which antimicrobial effect was related, carob pod extracts inhibited Cellvibrio fulvus and Clostridium cellulosolvens at 15 mug/ml, Sporocytophaga myxococcoides at 45 mug/ml, and Bacillus subtilis at 75 mug/ml. The inhibiting concentrations for tannic acid were found to be 12, 10, 45, and 30 mug/ml, respectively. Gallic acid and catechol were much less effective. Tannic acid and the tannin fraction of carob extract exerted both bacteriostatic and bactericidal effects on C. fulvus. Respiration of C. fulvus in the presence of bactericidal concentrations of tannic acid or tannin fraction of carob extract was inhibited less than 30%. A partial formation of "protoplasts" by C. fulvus was obtained after 2 hr of incubation in a growth medium to which 20% sucrose, 0.15% MgSO(4).7H(2)O, and 10 to 50 mug/ml of tannic acid or 500mug/ml of penicillin, or both, had been added. Tannic acid and the tannin fraction of carob extract protected C. fulvus from metabolic lysis in sucrose solution. Although the growth of other microorganisms tested was only slightly affected, the morphology of some of them was drastically changed in the presence of subinhibitory concentrations of carob pod extracts of tannic acid. It is suggested that the site of action of tannins on sensitive microorganisms is primarily the cell envelope.

Topics: Bacillus subtilis; Bacteria; Catechols; Clostridium; Culture Media; Enterobacter aerogenes; Escherichia coli; Galactans; Gallic Acid; Hydrolyzable Tannins; Mannans; Plant Gums; Plants, Edible; Pseudomonas; Research; Salmonella typhi; Shigella dysenteriae; Staphylococcus; Streptococcus; Tannins; Vibrio; Water

Topics: 17-Ketosteroids; Adrenalectomy; Ascorbic Acid; Catechols; Edema; Formaldehyde; Hyaluronoglucosaminidase; Inflammation; Pharmacology; Rats; Research; Tannins; Tea; Urine

Topics: Catechin; Catechols; Flavones; Tannins

Topics: Blood Pressure; Catechols; Muscles; Plants; Respiration; Tannins

Topics: Catechin; Catechols; Fagopyrum; Flavonoids; Fruit; Humans; Rutin; Tannins; Tea; Triticum; Vitamins; Vitis