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Catechol structure

COMT O-methylates catecholamines and other compounds having a catechol structure including catecholoestrogens (Fig. 2). The two isoforms of... [Pg.335]

As strong metal ion chelators due to their catechol structure, tea flavonoids are able to bind and thus decrease the level of free cellular ferric and ferrous ions, which are required for the generation of reactive oxygen radicals via the Fenton reaction (Yang and Wang, 1993). [Pg.138]

Complexes between heavy metals and catechol structures in the kraft lignin could theoretically contribute to the long wave absorption, but it is unlikely that their contribution to the color of the kraft lignin is very important. [Pg.101]

Native, as well as technical lignins, whether present in pulp (wood) or in the form of isolated samples, usually contain trace amounts of catechol structures These can be identified and quantified if the alkylation step in the oxidative degradation procedure is performed with diethyl sulfate since, in this case, various types of catechol units in the form of 1,2-diethoxybenzene derivatives are distinguished from guaiacyl and synngyl structures (Gellerstedt and Lindfors... [Pg.331]

The enzyme catechol-O-methyltransferase (COMT) is involved in pain regulation and regulation of neurotransmitters. COMT acts to catalyze the transfer of a methyl group from the cofactor S-adenosyl-L-methionine (SAM, 5) to the 0 of catecholate 4 (Reaction 9.5). The catechol structure is found in neurotransmitters such as dopamine, noradrenahne, and adrenaline. A related set of enzymes are the DNA methyltransferases that appear to have similar structure, especially in their active sites, to the structure of COMT. ... [Pg.582]

Frank, J., Budek, A., Lundh, T., Parker, R. S., Swanson, J. E., Lourenco, C. F., Gago, B., Laran-jinha, J., Vessby, B., Kamal-Eldin, A. (2006). Dietary flavonoids with a catechol structure increase alpha-tocopherol in rats and protect the vitamin from oxidation in vitro. J. Lipid Res., 47, 2718-2725. [Pg.585]

Flavonoids are widely distributed in fruits and vegetables and are very common nutritional supplements as antioxidants. The results on antioxidant activities of simple catechols provide a useful basis for evaluating results for the many, more complex natural compounds containing the catechol structure, such as the flavonoids, steroidal catechols and hormonal catecholamines. There are several reviews on the antioxidant properties of flavonoids and several reports on experimental " and theoretical evidence linking their antioxidant properties to the catechol moiety usually found in their structure. The basic flavonoid structure (29) is shown in Chart 1, with a few selected examples (30-36) from different groups to illustrate some of the relationships between their detailed structures and related antioxidant properties. Efforts to elucidate these relationships are hampered by their very low solubility in non-polar solvents, and the tendency of some researchers to employ metal ions as initiators of oxidation in aqueous media so that one cannot distinguish between their action as chain-breaking... [Pg.871]

The structural features responsible for their antioxidant properties (a) the catechol structure in ring B is most important, (b) the 2,3-double bond in conjunction with the 4-0X0 function provides additional, beneficial electron delocalization and (c) coplanarity of the system is beneficial and the 3-hydroxyl group may help lock a coplanar configuration. [Pg.895]

Phenolic OH in guaiacyl units and catechol structures COOH groups in aliphatic acids and cinnamic acids... [Pg.249]

When the B-ring possesses a catechol type structure, this nucleus acts mostly as a reducing agent. Once oxidized, it can undergo either coupled oxidation or Michael addition as a powerful electrophile, both mechanisms restore the catechol structure. The main grape anthocyanins, as their B-ring lacks the catechol hydroxylation pattern. [Pg.72]

The numerous health related properties of flavonoids, widely described in epidemiological studies, are mainly based on their antioxidant activities. These properties have been found to include anti-inflammatory and antiviral activities, effects on capillary fragility, inhibition of human platelet aggregation and anticancer activity. The antioxidant capacity of any flavonoid will be determined by a combination of the catechol structure in the B-ring, the 2,3-double bond in conjunction with a 4-oxo function, and the presence of both hydroxyl groups in positions 3 and 5. Due to their... [Pg.741]


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See also in sourсe #XX -- [ Pg.61 ]




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Catechol

Catechol (3-methyltransferase structure

Catechol Oxidase Structure and Function

Catechol crystal structure

Catechol dioxygenases structure

Catechol structural model

Catecholate

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