Chemistry of Sponges, XII. A New Dihydric Phenol from the Sponge Fasciospongia sp.

1991 ◽  
Vol 54 (1) ◽  
pp. 269-270 ◽  
Author(s):  
M. R. Kernan ◽  
R. C. Cambie ◽  
Patricia R. Bergquist
Keyword(s):  
Dihydric Phenol

scholarly journals The abundance of epiphytic liverworts on the bark of Cryptomeria japonica in relation to different physical and biochemical attributes, found in Senchal Wildlife Sanctuary, Darjeeling, Eastern Himalaya

BMC Ecology ◽  
2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Sumira Mukhia ◽  
Palash Mandal ◽  
D. K. Singh ◽  
Devendra Singh
Keyword(s):  
Forest Management ◽  
Light Intensity ◽  
Sustainable Forest Management ◽  
Principal Component ◽  
Biochemical Properties ◽  
Tree Cover ◽  
Eastern Himalaya ◽  
Wildlife Sanctuary ◽  
Dihydric Phenol ◽  
Old Trees

Abstract Background Maintenance of biodiversity is an integral part of sustainable forest management. Epiphytic bryophytes are an important element of biodiversity. Thus, this work aims to study the role of different physical and biochemical factors in affecting the growth and proliferation of epiphytic liverworts. Fifty trees in three different plots, distributed in Senchal wildlife sanctuary, Darjeeling, were surveyed. Factors such as light intensity, moisture, and diameter at breast height (DBH) of the tree were studied to evaluate their possible role in affecting epiphytic liverworts. The effect of bark biochemical characteristics on the abundance of epiphytic liverworts was also studied by undertaking a quantitative test of pH, phenol, flavonoid, ortho-dihydric phenol, terpene, total sugar, and tannin. Multiple regression analysis and principal component analysis (PCA) were carried out to test the effects of these parameters. Results Light intensity, moisture, and DBH highly influenced the abundance of liverworts. Old trees had higher epiphytic liverwort cover than younger ones. Bark biochemical properties like pH, phenol, flavonoid, ortho-dihydric phenol, tannin and sugar did not have a significant effect on the epiphytic liverwort cover, while the terpenoid content of the bark reduced liverworts cover. Conclusion To sustain the occurrence of epiphytic liverworts in ecosystems, forest management should ensure the presence of old trees. Light intensity and moisture had a large effect on the distribution and abundance of liverworts, so it is important to maintain tree cover, shrub layer, and tree density.

scholarly journals Studies in the Biochemistry of Micro-organisms. Part XV.—The Molecular Structure of Citrinin

1931 ◽  
Vol 220 (468-473) ◽  
pp. 297-300 ◽  
Keyword(s):  
Molecular Structure ◽  
Potassium Hydroxide ◽  
Side Chain ◽  
Hydroxyl Groups ◽  
Alkyl Side Chain ◽  
Present Communication ◽  
Colour Reaction ◽  
Dihydric Phenol ◽  
Resorcinol Derivative ◽  
Micro Organisms

The present communication is, in effect, a discussion of the results obtained in the investigation of citrinin, and described in the preceding memoir (Part XIV ); these results, combined with some few further observations, appear to afford a key to the constitution of the substance. In considering this matter, it is convenient to start with the dihydric phenol, C 9 H 12 O 2 (I) (p. 290), which was obtained by fusing either of the isomeric products A or B (p. 283) with potassium hydroxide. This dihydric phenol has the composition of a dihydroxypropylbenzene, but the relative position of the hydroxyl groups and the arrangement of the alkyl side-chain or chains is unknown. The colour reaction with ferric chloride is, however, in agreement with the view that the substance is a resorcinol derivative, rather less well in harmony with the catechol hypothesis, and is hardly reconcilable with the assumption of a quinol nucleus.

scholarly journals Electrocatalytic Oxidation of Dihydric Phenol on Polypyrrole Film Modified Electrodes

1995 ◽  
Vol 11 (05) ◽  
pp. 460-464
Author(s):  
Li Yi-Jun ◽  
◽  
Liu Jun-Li ◽  
Dong Shao-Jun
Keyword(s):  
Electrocatalytic Oxidation ◽  
Modified Electrodes ◽  
Polypyrrole Film ◽  
Dihydric Phenol

scholarly journals Oxidation of monohydric phenol substrates by tyrosinase: effect of dithiothreitol on kinetics

1994 ◽  
Vol 304 (1) ◽  
pp. 155-162 ◽  
Author(s):  
S Naish-Byfield ◽  
C J Cooksey ◽  
P A Riley
Keyword(s):  
Active Site ◽  
Direct Reduction ◽  
Reaction System ◽  
Adduct Formation ◽  
Lag Phase ◽  
Oxygen Utilization ◽  
Total Oxygen ◽  
Thiol Compounds ◽  
Monophenolase Activity ◽  
Dihydric Phenol

The effect of thiol compounds on the monophenolase activity of tyrosinase was investigated using 4-hydroxyanisole as the substrate and dithiothreitol (DTT) as the model thiol compound. We have demonstrated three actions of DTT on tyrosinase-catalysed reactions: (1) direct reduction of the copper at the active site of the enzyme; (2) generation of secondary, oxidizable species by adduct formation with the o-quinone reaction product, 4-MOB, which leads to an increase in the total oxygen utilization by the reaction system; and (3) reversible inhibition of the enzyme. We confirm our previous observation that, at approx. 10 mol of DTT/mol of enzyme, the lag phase associated with monohydric phenol oxidation by tyrosinase is abolished. We suggest that this is due to reduction of the copper at the active site of the enzyme by DTT, since (a) reduction of active-site copper in situ by DTT was demonstrated by [Cu(I)]2-carbon monoxide complex formation and (b) abolition of the lag at low DTT concentration occurs without effect on the maximum rate of reaction or on the total amount of oxygen utilized. At concentrations of DTT above that required to abolish the lag, we found that the initial velocity of the reaction increased with increasing DTT, with a concomitant increase in the total oxygen utilization. This is due to the formation of DTT-4-methoxy-o-benzoquinone (4-MOB) adducts which provide additional dihydric phenol substrate either directly or by reducing nascent 4-MOB. We present n.m.r. evidence for the formation of mono- and di-aromatic DTT adducts with 4-MOB, consistent with a suggested reoxidation scheme in the presence of tyrosinase. Inhibition of the enzyme at concentrations of DTT above 300 pmol/unit of enzyme was released on exhaustion of DTT by adduct formation with 4-MOB as it was generated.

Diarylheptanoid and other phenolic constituents of Centrolobium species

1984 ◽  
Vol 37 (5) ◽  
pp. 1127 ◽  
Author(s):  
L Jurd ◽  
RY Wong
Keyword(s):  
Forest Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Phenolic Constituents ◽  
Dihydric Phenol ◽  
The U.S

The heartwood of a specimen of Centrolobium tomentosum Benth (Leguminosae) has given (–)-centrolobine (1a), (–)-de-O-methylcentrolobine (1b), (–)-centrolobol (2), piceatannol (3)and the isoflavone formononetin (4). The heartwood of a second Centrolobium species, which could not be identified further at the U.S. Forest Products Laboratory, yielded (+)-centrolobine, (+)-de-O-methylcentrolobine, (+)-centrolobol, formononetin, 4',7-dihydroxyflavanone (5), 3-hydroxy-9-methoxypterocarpan (6) and minor amounts of a new dihydric phenol. This was identified by n.m.r. and X-ray diffraction measurements as 2-(2'-hydroxy-4'-methoxyphenyl)benzofuran-6-ol (8).

Comparative Studies of Brown Coal and Lignin. II. The Action of Concentrated Alkali at Elevated Temperatures

1960 ◽  
Vol 13 (4) ◽  
pp. 567 ◽  
Author(s):  
BM Lynch ◽  
RA Durie
Keyword(s):  
Functional Groups ◽  
Brown Coal ◽  
Comparative Studies ◽  
Elevated Temperatures ◽  
Carboxyl Groups ◽  
Hydroxyl Groups ◽  
Brown Coals ◽  
Simple Chemical ◽  
Phenolic Hydroxyl Groups ◽  
Dihydric Phenol

A study was made of the products formed by treating brown coal or lignin with concentrated aqueous or ethanolic alkali at 200 �C. With brown coals a major redistribution of the oxygen-containing functional groups appeared to occur, because the products contained aliphatically linked carboxyl groups and aliphatic hydroxyl, as well as phenolic hydroxyl groups. The behaviour of lignin under the same conditions was less clear but sufficiently similar to that of brown coal to suggest that reactions of the same type were occurring in both cases. Reactions involving decarboxylation, ring scission of dihydric phenol structures, and subsequent hydrogenation are suggested tentatively as the main steps in the formation of the products. The results provide some additional evidence for the view that there is a simple chemical relation between Victorian brown coal and lignin.

scholarly journals Tyrosinase kinetics: failure of the auto-activation mechanism of monohydric phenol oxidation by rapid formation of a quinomethane intermediate

1998 ◽  
Vol 333 (3) ◽  
pp. 685-691 ◽  
Author(s):  
Christopher J. COOKSEY ◽  
Peter J. GARRATT ◽  
Edward J. LAND ◽  
Christopher A. RAMSDEN ◽  
Patrick A. RILEY
Keyword(s):  
Rate Constant ◽  
Pulse Radiolysis ◽  
Phenol Oxidation ◽  
Activation Mechanism ◽  
Oxygen Stoichiometry ◽  
Oxygen Utilization ◽  
Maximum Acceleration ◽  
Semiquinone Radicals ◽  
Catalysed Oxidation ◽  
Dihydric Phenol

When 3,4-dihydroxybenzylcyanide (DBC) is oxidized by mushroom tyrosinase, the first visible product, identified as the corresponding quinomethane, exhibits an absorption maximum at 480 nm. Pulse-radiolysis experiments, in which the o-quinone is formed by disproportionation of semiquinone radicals generated by single-electron oxidation of DBC, showed that the quinomethane (A480 6440 M-1·cm-1) is formed through the intermediacy of the o-quinone with a rate constant at neutral pH of 7.5 s-1. The oxygen stoichiometry of the formation of the quinomethane by tyrosinase-catalysed oxidation of DBC was 0.5:1. On the basis of oxygen utilization rates the calculated Vmax was 4900 nmol·min-1 and the apparent Km was 374 µM. The corresponding monohydric phenol, 4-hydroxybenzylcyanide (HBC), was not oxidized by tyrosinase unless the enzyme was pre-exposed to DBC, the maximum acceleration of HBC oxidation being obtained by approximately equimolar addition of DBC. These results are consistent with tyrosinase auto-activation on the basis of the indirect formation of the dihydric phenol-activating cofactor. The rapid conversion of the o-quinone to the quinomethane prevents the formation of the catechol by reduction of the o-quinone product of monohydric phenol oxidation from occurring in the case of the compounds studied. In the absence of auto-activation, the kinetic parameters for HBC oxidation by tyrosinase were estimated as Vmax 70 nmol·min-1 and Km 309 µM. The quinomethane was found to decay with a rate constant of 2k 38 M-1·s-1, as determined both by pulse-radiolysis and tyrosinase experiments. The second-order kinetics indicate that a dimer is formed. In the presence of tyrosinase, but not in the pulse-radiolysis experiments, the quinomethane decay was accompanied by a steady-state oxygen uptake concurrently with the generation of a melanoid product measured by its A650, which is ascribed to the formation of an oligomer incorporating the oxidized dimer.

Two distinct S-adenosyl-l-methionine:3,4-Dihydric phenol 3-O-methyltransferases of phenylpropanoid metabolism in soybean cell suspension cultures

1976 ◽  
Vol 173 (1) ◽  
pp. 301-305 ◽  
Author(s):  
Jonathan Poulton ◽  
Hans Grisebach ◽  
Jürgen Ebel ◽  
Bärbel Schaller-Hekeler ◽  
Klaus Hahlbrock
Keyword(s):  
Cell Suspension ◽  
Cell Suspension Cultures ◽  
Suspension Cultures ◽  
Phenylpropanoid Metabolism ◽  
Dihydric Phenol ◽  
Soybean Cell

scholarly journals CONTENT OF PROTEIN AND ORTHO-DIHYDRIC PHENOL IN AGARICUS BISPORUS X25 CULTIVATED ON DECOMPOSED AGROSUBSTRATES

2017 ◽  
Vol 42 (3) ◽  
pp. 324-328
Author(s):  
Mustafa Nadhim Owaid ◽  
◽  
Mowafaq Mezban Muslat ◽  
Idham Ali Abed
Keyword(s):  
Agaricus Bisporus ◽  
Dihydric Phenol
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