Presence Of Pyrocatechol Research Articles

First extraction of polyphenol oxidase from edible desert truffle (Terfezia leonis Tul.) and its thermal behavior

Polyphenol oxidase (PPO) is a common enzyme with large applications in food processing and analysis, especially based on their monophenolase activity. In this context, extraction and surfactant-mediated activation of PPO from desert truffle Terfezia leonis Tul. were successfully achieved. In the presence of l-tyrosine, the cresolase activity was optimal in the pH 5–6 domain and in the 35–45 °C temperature range. In the presence of pyrocatechol, the catecholase activity was optimal at neutral pH and 30 °C. Kinetics studies revealed higher affinity of PPO for l-tyrosine than for pyrocatechol. Both enzyme–substrate complexes were structurally robust, and their thermosensitivity was mainly related to entropy changes. These properties may reflect the adaptation to desert conditions where T. leonis grows and should be useful for the development of enzymatic catalysts and sensors.

Вплив комплексів заліза на формування фотосинтетичного апарату та вихід генетичних змін у гамма-опроміненого насіння пшениці

Influence of various doses of γ-irradiation on biosynthesis of chlorophyll and carotinoids, and also on a progress of mitotic divisions of meristematic cells of root hairs at sprouting wheat seeds at the presence of pyrocatechol, iron pyrocatecholat, thiocarbamide, iron thiocarbamide, rutine, iron rutinate, juglon and iron juglonate was studied. There was revealed that iron pyrocatecholate, iron rutinate, juglon and iron juglonate possess appreciable radioprotective properties which stimulate adaptive biosynthesis of chlorophyll and carotinoids, and also considerably reduce a number of chromosomal aberrations under irradiation.

Synthesis of O,O Ethane Bridged Bis-copper(II) Macrocycles. Selective Enzyme Model for Catecholase Activity

New mononuclear and dinuclear complexes [3-hydroxyethyl-1,3,5,8,11pentaazacyclotridecane]copper(II) (1)/nickel(II) (2) perchlorate and O,O ethane bridged bis-copper(II) (3)/nickel(II) (4) macrocycles have been synthesized and characterized by various spectroscopic techniques, viz. i.r., n.m.r., e.p.r., u.v.–vis. and conductance measurements. Spectral data and conductance measurements reveal that all the complexes are consistent with square-planar geometry and are ionic in nature. The catalytic activity of the dinuclear Cu(II) complex (3) in the presence of pyrocatechol was determined spectrometrically by monitoring the increase of the o-benzoquinone characteristic absorption band at 25,000 cm−1 with respect to time in DMF saturated with molecular oxygen. The kinetic parameters Vmax (2.8×10−3 M s−1) and KM (1.4×10−3 mm) have been determined by Michaelis–Menten method. Electrochemistry of the dinuclear Cu(II) complex has been studied in the presence of molecular oxygen with pyrocatechol and without pyrocatechol at a scan rate of 0.1 V s−1 by cyclic voltammetry. On addition of pyrocatechol, complex shows a shift in Epc, Epa and E1/2 values indicating the oxidation of substrate (pyrocatechol).

Synthesis of new dinuclear dicopper(II) and dinickel(II) complexes. The kinetics of catechol oxidase and electrochemistry of a dicopper(II) complex

A new dinuclear ligand L′, ethylene[OO′-bis-salicylidene-β-diketone] bearing two symmetrical coordination sites was synthesized by the condensation of salicylaldehyde and acetylacetone, L, with 1,2-dibromoethane under reflux. The ligand L′ in a 1:1 ratio was treated with CuCl2 and NiCl2 to yield the complexes, tetrachloro bis[OO′-bis- salicylidene-β-diketone copper(II)] and bis[OO′-bis-salicylidene-β-diketone nickel(II)] chloride. The complexes were subsequently characterized by spectroscopic techniques, elemental analysis, i.r., 1H-n.m.r., 13C-n.m.r., u.v.–vis., e.p.r. spectroscopy, and conductance measurements. The conductance measurements in DMF reveal that the CuII complex is covalent while the NiII complex is ionic and the spectral data support the CuII complex to be distorted octahedral whereas the NiII complex has square-planar geometry. The dioxygen binding was studied spectrophotometrically by the oxidation of tetrachloro bis[OO′-bis-salicylidene-β-diketone copper(II)] with pyrocatechol in the presence of oxygen. The kinetic experiments were performed with the copper complex in DMF by monitoring the increase in absorbance over time at pH 8.0 in the presence of pyrocatechol at 25 °C. The kinetic parameters Vmax and KM were determined on the Michaelis–Menten Approach. Redox behavior of the dinuclear copper(II) complex was investigated by cyclic voltammetry in the presence of O2 with the pyrocatechol (substrate) and also without the substrate. The large difference in potentials E0 is indicative of reversible oxygen binding of the complex and distinct catalytic activity.

The role of pyrocatechol as a complex agent for silicon in the synthesis of large single crystals of silica-sodalite zeolite

To investigate the role of a complex agent in synthesizing large single crystals of silica-sodalite, pyrocatechol was added as an additive to the system SiO 2–NaOH–EG (EG=ethylene glycol). Experimental results showed that the crystals synthesized in the presence of pyrocatechol have much larger size and better morphology than those synthesized in the absence of pyrocatechol. The role of pyrocatechol in the hydrothermal reaction mixture was investigated by 29Si NMR, IR, and UV–vis spectroscopy, and it was shown that a silicon–pyrocatechol complex was formed in the reaction system.

Mechanism of Silica Gel Dissolution in Water in the Presence of Pyrocatechol

Abstract The rates of dissolution of silica gel in aqueous alkaline solutions containing pyrocatechol were measured. At pH 10, all of the silica gel was dissolved in the presence of pyrocatechol at 25 °C for 48 h (SiO2 0.3 g and pyrocatechol 0.04 mol in 15 ml of water). The rates of silica-gel dissolution increased with increasing pyrocatechol concentration. Four moles of pyrocatechol were needed to dissolve one mole of SiO2. The rate of dissolution was first order in solid SiO2 concentration. Langmuir-type adsorption of pyrocatechol to the silica-gel surface was assumed to explain the rate dependence on the pyrocatechol concentration.

Pentaco-ordinate silicon compounds in synthesis: Regiospecific allylation of aldehydes using trialkoxy-substituted allylsilane, pyrocatechol, and an amine.

Aliphatic and aromatic aldehydes are allylated with trialkoxysubstituted allylsilane to give the corresponding homoallyl alcohols regiospecifically in the presence of pyrocatechol and triethylamine without solvent at 60°C or in tetrahydrofuran at reflux. The allylation reaction takes place even in a protic solvent such as methanol and ethanol.

Degradation of 3-chlorobenzoate in soil by pseudomonads carrying biodegradative plasmids.

Degradation of continuously added 3-chlorobenzoate (3-CB) was studied in samples of chernozem soil. Soil columns were inoculated with Pseudomonas putida growing on 3-CB and carrying the biodegradation plasmid and with Pseudomonas aeruginosa incapable of growth on 3-CB and carrying the inserted biodegradation plasmid pBS 2 determining ortho-cleavage of the aromatic ring. While the 3-CB degradation was observed in both inoculated variants, the native microflora of the soil under study was incapable to degrade 3-CB. Among pseudomonads isolated from inoculated soil at different stages of cultivation and growth on 3-CB, some had the taxonomic features of P. putida as well as those differing in 1-5 characteristics. The study of the activities of the enzymes cleaving the aromatic ring revealed the presence of pyrocatechol 1,2-dioxygenase in the isolated strains only, as estimated by means of benzoate and 3-CB as substrates.

The reduction of acetylene by complexes of the transition metals with pyrocatechol

1. The reduction of acetylene by complexes of transition metals [V(II), Ti(III), Cr(II), Mo(III] in the presence of pyrocatechol at various pH of the solutions was studied, 2. In the reaction of deuteroacetylene with V(II), cis-dideuteroethylene is formed, with Ti(III) a mixture of the cis- and trans-isomers, and with Cr(II) and Mo(III) only the trans-isomer.

SOME INOCULUM AND SUBSTRATE FACTORS IN THE CULTURAL INHIBITION OF HYPOXYLON PRUINATUM (KLOTZSCHE) CKE. BY PYROCATECHOL

The experimental results indicated that the type of inoculum was a critical factor in the ability of Hypoxylon pruinalum (Klotzsche) Cke. to colonize 2% Difco Bacto malt agar containing 640 p.p.m. of pyrocatechol, or plates with 10% autoclaved bark meal of Populustremuloides Michx. in 2% water agar. Hypoxylon failed to become established on these media when the inoculum consisted of agar plugs from the margin of 5- to 7-day-old colonies on 2% Difco Bacto malt agar. However, the fungus did colonize the same plates when infected portions of autoclaved bark meal of P. tremuloides were used as the inoculum. Apparently, the total inhibition of Hypoxylon on these media was related to the use of the agar plug type of inoculum rather than to the concentration of fungistatic substances in the media. The most rapid growth of Hypoxylon on malt agar containing pyrocatechol occurred in the colonies that developed from infected portions of untreated bark meal of P. tremuloides. In these cultures Hypoxylon grew in association with bark saprophytes that appeared to act on the pyrocatechol and provide a more favorable medium for the growth of the fungus.It was demonstrated that the nutritional properties of the untreated bark of P. tremuloides were more favorable to the growth of Hypoxylon than those of autoclaved bark. The growth of the fungus was strongly inhibited on malt agar containing suspensions of autoclaved bark and 640 p.p.m. of pyrocatechol. Excellent growth occurred when the medium contained suspensions of untreated bark and the additional pyrocatechol. Apparently, the development of the bark saprophytes inactivated the pyrocatechol in the medium and the untreated bark tissues and prevented the chemical inhibition of Hypoxylon. Therefore, the nutritional and microbiological factors of untreated bark were such that the fungus could grow and survive in these tissues despite the presence of pyrocatechol. However, the saprophytic microfloras of most samples of untreated bark included Trichoderma sp. and (or) Aspergillus sp., which overcame the competition from the other saprophytes and were mutually antagonistic with Hypoxylon. The growth of the fungus was inhibited when the untreated bark tissues were colonized by these saprophytes.

Differential Reactions Between Carotene and Oils Rich in Vitamin A

It has recently been demonstrated that carotene gives characteristic color reactions with trichloracetic acid, with chloral hydrate and with a reagent containing a mixture of sulphuric acid and formaldehyde. Tested on the rat, carotene in a biologic sense behaves in a manner similar to vitamin A. From a chemical standpoint, carotene shows a striking resemblance to vitamin A. One molecule of vitamin A is equivalent to half a molecule of carotene. Carotene and vitamin A both yield a characteristic blue color with antimony trichloride. The blue chloroform reaction mixture obtained with carotene in the presence of antimony trichloride yields, however, an absorption band at 590 mu, while the reaction mixture with vitamin A yields a wider absorption band at 610–630 mu. Recently Rosenthal and Erdelyi have demonstrated the possibility of distinguishing between carotene and vitamin A by applying the antimony trichloride test in the presence of pyrocatechol. They observed that when oil rich in vitamin A or vitamin A concentrate is dissolved in absolute chloroform and heated with antimony trichloride reagent and 0.5% pyrocatechol in chloroform solution, the blue changes to a purple or violet-red color comparable with the one characteristic of an aqueous solution of potassium permanganate. More recently Rosenthal and Erdelyi have demonstrated that in addition to pyrocatechol, hydroquinone, quaiacol and veratrole may be employed. Andersen and Levine have studied their procedure and report positive tests with antimony trichloride with vitamin Arich oils in the absence of pyrocatechol or any other phenol. They observed that pyrocatechol is even detrimental, since it inhibits the reaction and diminishes its sensitivity.