Ethoxyresorufin-O-deethylation

In this study, we have utilized 2,2, 4,4 -tetrachlorobiphenyl and 3,3, 4,4 -tetrachlorobiphenyl as representative non-coplanar and coplanar isomers respectively. The 3,3, 4,4 -tetrachlordbi-phenyl isomer (0.3mmole/kg) induced ethoxycoumarin-and ethoxy-resorufin-O-deethylations in the rainbow trout to a similar extent as did Aroclor 1242 (Table III). However, the non-coplanar 2,2 -4,4 -tetrachlorobiphenyl was without effect upon any of the monooxygenase activities examined. Cytochrome P -450-like activity as determined by ethoxyresorufin-O-deethylation was increased by the planar 3,3, 4,4 -tetrachlorobiphenyl while cytochrome P-450-like activity (benzphetamine-N-demethylation) was unaffected. 

CYP1A1 Mainly ex-trahepatic CYP1A1 2 CYP1A1 3 7-ethoxyresorufin O -deethylation alpha-N aphthoflavone (acceptable1, inhibits also CYP3A4) Polycyclic hydrocarbons < 1%... 

Acute exposure to allyl alcohol causes liver and kidney damage. Allyl alcohol is classified as a periportal hepatotoxicant since it selectively damages the periportal region of the liver. Studies have shown that in adult rats, allyl alcohol produces a moderate to marked periportal necrosis with attendant inflammation, hemorrhage, and also decreases hepatic cytochrome P-450, benzphentamine N-demethyla-tion, and ethoxyresorufin 0-deethylation activities by 30%. In immature rats, it lowered both cytochrome P-450 activity (30%) and ethoxyresorufin O-deethylation (75%). Benzphetamine N-demethyl-ation was not significantly affected in immature rats. Intraperitoneal administration of 1.5 mmol kg of allyl alcohol to starved Swiss albino mice causes the development of hemolysis in 50% of the animals. Other toxic effects include renal necrosis, pulmonary edema, and central nervous system effects at higher dose levels. 

Human P450 IBl, like P450 lAl, has never been purified from tissue and all of our information has come from protein expressed in heterologous systems. 7-Ethoxyresorufin O-deethylation... 

A2 Caffeine iV3-demethylation Phenacetin O-deethylation 7-Ethoxyresorufin O-deethylation Smoking Charcoal-broiled foods Cruciferous vegetables Omeprazole Furafylline" Galangin" Caffeine... 

A decrease in expression of the GYPIA drug-metabolizing isoenzymes was observed in mice orally or intraperi-toneally administered 10 mg/kg of the compound lentinan every other day for four doses (Okamoto et al. 2004). In mice intraperitoneally administered 10 mg/kg of the compound lentinan every other day for four doses, suppression of constitutive and 3-methylcholanthrene-induced GYPIA expression and ethoxyresorufin-O-deethylation activity in the liver was observed (Hashimoto et al. 2002). 

Methanol inhalation (0, 1000, 2500, or 10000 ppm for 6h) potentiated CCI4 hepatotoxicity in Fischer 344 male rats (Allis et al. 1996). Hepatic microsomes showed increased p-nitrophenol hydroxylase activity but no increase in pentoxyreso-rufin-O-dealkylase or ethoxyresorufin-O-deethyl-ase activities. Hepatic antioxidant levels, glutathione levels and glutathione-S-transferase activity in methanol-treated animals were not different from controls. Pre-treatment with allyl sulphone, a specific chemical inhibitor of CYP2E1, abolished the difference in microsomal metabolism between exposed and control animals. 

Figure 2 Effects of i.p.-injectedpolysaccharides on the level and activity of cytochrome P450s (CYPs). Mice were intraperitoneally administered polysaccharides and /or MC as described in Figure 1. (A) Microsomal proteins were prepared from the liver, and the total CYP contents and (B) the ethoxycoumarin O-deethylation (ECOD) and (C) ethoxyresorufin O-deethylation (EROD) activities were measured as described in Materials and...

Burke, M.D. and Mayer, R.T. Ethoxyresorufin Direct fluori-metric assay of a microsomal O-deethylation which is preferentially inducible by 3-methylcholanthrene. Drug. Metab. Disp. (1974) 2 583-588. 

The previous discussion has illustrated the role of monooxygenase systems in fish for the metabolism of xenobiotics. Measurements of this activity have therefore been used as a measure of the extent to which fish have been exposed to xenobiotics at the same time, of course, increased levels enable the fish to metabolize xenobiotics effectively (Kleinow et al. 1987). Although specific assays of cytochrome P-450 activity may be made by immunoblot methods (Monosson and Stegeman 1991), it may be expedient to measure specific enzyme activity using defined substrates. Two assays have been widely used (1) aryl hydrocarbon hydroxylase activity that may be assayed using benzo[a]pyrene as substrate, although this substrate has been replaced recently by the less hazardous 2,5-diphenyloxazole, and (2) activity for O-deethylation of 7-ethoxyresorufin (EROD) has been extensively used and is a simple and convenient assay. 

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