Metabolites, phenolic

Fluorinated Muconates Formed from Fluorophenols by Phenol Hydroxylase and Catechol 1,2-Dioxygenase from Exophilia jeanselmei Fluoromuconate Metabolite Phenolic Substrate(s)... 

Description of the model. Benzene and its metabolites (phenol, catechol, and hydroquinone) were assumed to compete for the same reaction site on the enzyme cytochrome P-450 2E1. In addition, phenol can undergo both oxidation and conjugation, although the enzymes for each of these reactions are localized in different compartments of the liver, and competition between them is thereby regulated. 

Chen H, Eastmond DA. 1995a. Synergistic increase in chromosomal breakage within the euchromatin induced by an interaction of the benzene metabolites phenol and hydroquinone in mice. Carcinogenesis 16 1963-1969. 

Legathe A, Hoener B-A, Tozer TN. 1994. Pharmacokinetic interaction between benzene metabolites, phenol and hydroquinone, in B6C3F1 mice. Toxicol Appl Pharmacol 124 131-138. 

The biomarker should be specific for the chemical or metabolites of interest that is, it needs to be an unambiguous marker of exposure. Measurement of the unchanged parent chemical may have greater specificity than that of the metabolite, which may be common to several substances (Bernard and Lauwerys 1986). For example, if the metabolite of the parent chemical is being measured, the result may be equivocal if the same metabolite is produced endogenously or formed after exposure to other compounds. Occupational exposure to high air concentrations of benzene was formerly monitored by testing for its metabolite, phenol, in urine. However, the use of phenol to measure small environmental exposures to benzene is problematic in that many foods contain phenol, and the normal... 

Benzene was also distributed to the kidney, lung, liver, brain, and spleen. The benzene metabolites phenol, catechol, and hydroquinone were detected in blood and bone marrow following 6 hours of exposure to benzene, with levels in bone marrow exceeding the respective levels in blood. The levels of phenol in blood and bone marrow decreased much more rapidly after exposure ceased than did those of catechol or hydroquinone, suggesting the possibility of accumulation of the latter two compounds. 

The primary metabolite of benzene is phenol. Phenol is excreted as glucuronide and sulphate conjugates in urine. Total phenolic metabolites (phenol, phenyl sulfate, and phenyl glucuronide) have been determined by hydrolyzing urine samples either enzymatically or by acid, then extracting the phenol with solvent. Phenol is then measured by GC or HPLC techniques. Enzymatic hydrolysis coupled with GC/FID has been reported the detection limit is 1 mg/L and recovery is excellent (92-98%) (Buchet 1988). Acid hydrolysis followed by HPLC provides quantitative recovery ( 100%) and a detection limit of 0.01 nmol/g (Murray and Adams 1988). Sulfate and glucuronide conjugates... 

The presence of high levels of pentachlorophenol in mammalian blood is well-known. The fact that as many as 120 or more phenolic OHS are present in both human and fish (salmon) blood demonstrates, in addition to lipid rich tissues, the potential importance of blood for the accumulation of environmental contaminants or their metabolites. Phenolic OHS are not strongly accumulated... 

Grimmer G, Dettbarn G, Jacob J. 1993. Biomonitoring of polycyclic aromatic hydrocarbons in highly exposed coke plant workers by measurement of urinary phenanthrene and pyrene metabolites (phenols and dihydrodiols). In Arch Occup Environ Health 65(3) 189-199. 

Phenol. Intravascularly injected phenol was very rapidly eliminated from hemolymph, with an elimination half life of 14 minutes for parent phenol (68). The route of elimination of phenol was dose dependent. At a dose of 0.1 mg/kg, about 35% of the administered drug was eliminated across the gills into the tank water in the first 30 minutes, and the remainder was converted to phenyl sulfate and eliminated from hemolymph into urine with an elimination half life of 6.3 hr in males and 11.9 hours in females (68). At doses above 2 mg/kg, >90% of the dose was excreted across the gills. Because its properties are such that it can be either excreted across the gills, or conjugated with sulfate to a readily excreted metabolite, phenol was not retained by the lobster. 

MeUdwlites Some moss species contain considerable amounts of aiachidonic acid. M. form a surprising diversity of previously unknown secondary metabolites. Phenolic compounds and terpenes dominate although clear differences between the individual classes of M. are apparent. Anthocerotae are characterized by lig-nans, liverworts mainly by terpenes - mostly sesquiterpenes (often enantiomers of those occurring in higher plants) - and bibenzyl or bisbibenzyl derivatives, Musci by the occurrence of biflavonoids, sphagnorubins (peat mosses) and coumarin derivatives (Polytrichaceae). Alkaloids are very rare. Recently sterile cultures (in vitro culmres ) have been introduced to obtain the secondary metabolites from M. The production of substances corresponds qualitatively to that of M. in natural locations. 

For more complex metabolites (phenols and tetraacetic acid lactone), further condensation of the triacetyl residue must take place and can only proceed if the priming acetyl residue, with its C-5 oxygen function, is stabilized away from the thioester region of the acyl-enzyme intermediate at this time. Possibly, the presence of NADPH assists in this process, in appropriate enzymes, since the ability to form triacetic acid lactone has been demonstrated by fatty acid and 6-methylsalicylate synthetases when deprived of this nucleotide, but other synthetases have not been tested for this effect. Moreover, the analogous formation of the styrylpyrone bisnoryangonin by flavan-one synthase (Kreuzaler and Hahlbrock, 1975a,b) confirms that the potential for synthesis of stable products with shorter chains does exist. 

The biosynthetic pathways are universal in plants and are responsible for the occurrence of both primary metabolites (carbohydrates, proteins, etc.) and secondary metabolites (phenols, alkaloids, etc.). Secondary compounds were once regarded as simple waste products of a plant s metabolism. However, this argument is weakened by the existence of specialist enzymes, strict genetic controls and the high metabolic requirements of these componnds (Waterman and Mole 1994). Today most scientists accept that many of these componnds serve primarily to repel grazing animals or destrnctive pathogens (Cronquist 1988). 

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