nitrophenols and lauric-acid

The aim of this study was to evaluate diazepam and oxazepam as cytochrome P450 inducers at doses previously shown to cause liver tumors in mice but not rats. In rats, diazepam and oxazepam induced CYP2B, and were as effective as phenobarbital despite lacking phenobarbital's tumor-promoting effect in rats. In mice, diazepam and oxazepam induced both CYP2B and CYP4A at dietary doses associated with liver tumor formation. It remains to be determined why diazepam and oxazepam induce CYP4A in mice but not rats and whether this difference accounts for the apparent species difference in the tumor-promoting activity of diazepam and oxazepam.

Topics: Animals; Benzodiazepines; Blotting, Western; Body Weight; Carcinogens; Cytochrome P-450 CYP1A1; Cytochrome P-450 CYP2B1; Cytochrome P-450 CYP4A; Cytochrome P-450 Enzyme System; Diazepam; Hypnotics and Sedatives; Immunohistochemistry; Isoenzymes; Lauric Acids; Liver Neoplasms; Male; Mice; Microsomes, Liver; Nitrophenols; Organ Size; Oxazepam; Phenobarbital; Rats; Rats, Sprague-Dawley

The aim was to characterize mouse gender and strain differences in the metabolism of commonly used human cytochrome (CYP) P450 probe substrates. Thirteen human CYP probe substrates (phenacetin, coumarin, 7-ethoxy-4-trifluoromethyl coumarin, amiodarone, paclitaxel, diclofenac, S-mephenytoin, bufuralol, dextromethorphan, chlorzoxazone, p-nitrophenol, testosterone and lauric acid) were used in activity measurements. The metabolism of the probe substrates was compared in liver microsomes from male and female NMRI, CBA, C57bl/6, 129/SvJ and CD1 strains. The expression of proteins identified on Western blots with commonly available antibodies selective for specific human and rat CYP enzymes were compared in the different mouse strains. Males had higher metabolism than corresponding females for phenacetin O-deethylation (human marker for CYP1A2 activity), and a high correlation was found between phenacetin activity and immunoreactivity in Western blots produced with rat CYP1A2 antibodies. Protein detected by antibodies cross-reacting with human CYP2B6 and rat CYP2B1/2 antibodies was female specific except for the 129/SvJ strain, where it was absent in both genders. Females generally had a higher metabolism of bufuralol 1'-hydroxylation and dextromethorphan O-demethylation (human markers for CYP2D activity). Bufuralol 1'-hydroxylation correlated with a female-dominant mouse CYP, which was detected with antibodies against rat CYP2D4. p-Nitrophenol 2-hydroxylation correlated better than chlorzoxazone 6-hydroxylation with the protein detected with antibodies against rat CYP2E1, indicating that p-nitrophenol is a more specific substrate for mouse CYP2E1.

Topics: Amiodarone; Animals; Aryl Hydrocarbon Hydroxylases; Blotting, Western; Chlorzoxazone; Coumarins; Cytochrome P-450 CYP1A2; Cytochrome P-450 CYP2B6; Cytochrome P-450 Enzyme System; Dextromethorphan; Diclofenac; DNA, Complementary; Ethanolamines; Female; Humans; Kinetics; Lauric Acids; Male; Mephenytoin; Mice; Mice, Inbred C57BL; Mice, Inbred CBA; Microsomes, Liver; Mixed Function Oxygenases; NADP; Nitrophenols; Oxidoreductases, N-Demethylating; Oxygen; Paclitaxel; Phenacetin; Rats; Sex Factors; Species Specificity; Substrate Specificity; Testosterone

Cytochrome P450 (CYP)-dependent oxidation of lauric acid, p-nitrophenol and ethanol by microsomal fractions of kidney were studied in control rats and in animals given either ethanol, red wine, or alcohol-free red wine for 10 weeks. Ethanol increased the total CYP content and specifically CYP 2E1, as well as p-nitrophenol and ethanol oxidation. The effects of ethanol treatment on the content and activity of CYP 2E1 were attenuated when red wine was administered, while the alcohol-free red wine values were similar to those of the control group. Although lauric acid hydroxylation was decreased by red wine treatment, the content of CYP 4A1 was not influenced by drinking fluids. We conclude that red wine administration attenuates the ethanol-induced enhancement of microsomal activities dependent on CYP 2E1 of rat kidney. Our results suggest that the non-alcoholic constituents of red wine could account for this modulation.

Topics: Animals; Antioxidants; Blotting, Western; Central Nervous System Depressants; Cytochrome P-450 Enzyme System; Densitometry; Ethanol; Kidney; Lauric Acids; Male; Microsomes; Nitrophenols; Oxidation-Reduction; Rats; Rats, Wistar; Wine

Cytochrome P450-dependent oxidation of lauric acid, p-nitrophenol and ethanol by liver microsomal fractions were studied in control rats and in animals given either ethanol, red wine, or alcohol-free red wine for 10 weeks. Ethanol increased the total cytochrome P450 and the isoenzyme 2E1 content, as well as the p-nitrophenol hydroxylation and ethanol oxidation. These effects of ethanol treatment were attenuated by red wine administration. Red wine increased the total antioxidant capacity of plasma, whereas the alcohol-free red wine decreased the cytochrome P450 content and decreased the oxidation of lauric acid, p-nitrophenol and ethanol to values lower than control. It is concluded that red wine administration attenuates the ethanol-induced enhancement in liver microsomal parameters dependent on cytochrome P450 2E1 activity, an affect that seems to be accomplished by the non-alcoholic constituents of red wine known to have antioxidant properties.

Topics: Animals; Antioxidants; Cytochrome P-450 CYP2E1; Ethanol; Flavonoids; Lauric Acids; Liver; Male; Microsomes, Liver; Nitrophenols; Oxidation-Reduction; Phenols; Polymers; Polyphenols; Rats; Rats, Wistar; Time Factors; Wine

(1) Lipases A and B from Candida rugosa catalyzing the hydrolysis of esters in micellar media have been characterized kinetically by studies on substrate specificity, rate equation forms and modeling of enzyme mechanisms. (2) The study on specificity revealed that both lipases are non-specific esterases with similar activity against lipid p-nitrophenyl esters micellized with Triton X-100. The slight difference was that lipase A has its maximum activity centered in the caprylate while that of lipase B is in the laurate. (3) Kinetic studies for both lipases were carried out with p-nitrophenyl laurate under three experimental conditions: (I) the molar fraction of substrate is fixed and the bulk concentration of substrate and Triton X-100 are varied; (II) the bulk concentration of substrate is held constant and the molar fraction of substrate and bulk concentration of Triton X-100 are varied; and (III) the bulk concentration of Triton X-100 is held constant but the bulk concentration of substrate and molar fraction of substrate are varied. (4) In case I, a similar Michaelis-Menten behaviour was observed with both lipases; the curve fitting gave kappcat/Kappm values of 3.0.10(5) and 5.6.10(5) s-1 M-1 for lipases A and B respectively. In case II, for both lipases the relationship between rate and the molar fraction of substrate required a fitting equation of 2:2 degree polynomial quotient. In case III, both lipases showed non-Michaelian behaviour with concave-up curves in the Eadie-Hofstee plot, a minimum degree of 2:2 in substrate concentration being detected for the rate equation. (5) The above results are interpreted in terms of the hypothesis that the mechanism of both lipases must include at least two different inputs for the molecule of substrate which would explain the quadratic terms observed in the rate equation.

Topics: Candida; Caprylates; Esters; Hydrolysis; Isoenzymes; Kinetics; Lauric Acids; Lipase; Micelles; Models, Chemical; Nitrophenols; Substrate Specificity

Many assay procedures have been devised to measure lipolytic activity, but none is without problems. It is for this reason that new methods are still being proposed. In this work we have investigated the use of two esters of p-nitrophenol, the palmitic acid and lauric acid esters, as substrates for a highly sensitive high-performance liquid chromatographic method. Data on recovery, specific activity and reproducibility are reported only for the lauric ester, because the palmitic ester turned out to be a very poor substrate.

Topics: Animals; Chromatography, High Pressure Liquid; Kinetics; Laurates; Lauric Acids; Lipase; Nitrophenols; Palmitic Acid; Palmitic Acids; Reproducibility of Results; Substrate Specificity