nitrophenols and 4-phenylphenol

A UDP-glucuronyltransferase isoform glucuronizes phenolic xenobiotics such as 4-nitrophenol, and an isoform glucuronizing 4-hydroxybiphenyl has also been found in rat liver. We purified a UDP-glucuronyltransferase isoform glucuronizing 4-hydroxybiphenyl from bovine liver microsomes by solubilization with 0.7% sodium cholate followed by three column chromatographic separations using DEAE-Toyopearl 650S, UDP-hexanolamine Sepharose 4B, and hydroxyapatite. The purified bovine liver 4-hydroxybiphenyl UDP-glucuronyltransferase (named Bovine 4HBGT) had glucuronidation activities toward 4-hydroxybiphenyl and 4-methylumbelliferone but had little activity toward 4-nitrophenol and 1-naphthol. The apparent molecular mass of Bovine 4HBGT was 54,000 Da on SDS-PAGE, and this was decreased to 50,000 Da by digestion with endo-beta-N-acetylglucosaminidase H. These data suggest that Bovine 4HBGT consists of a 50,000 Da polypeptide and a high mannose type oligosaccharide chain(s) of about 4,000 Da. The NH2-terminal sequence of GT-3 was GKVLVWPVDFSXWINI. These properties of Bovine 4HBGT were very similar to those of rat UDP-glucuronyltransferase glucuronizing xenobiotics. However, the NH2-terminal sequence of Bovine 4HBGT had higher homology with that of rat liver 4-hydroxybiphenyl UDP-glucuronyltransferase than with that of rat liver 4-nitrophenol UDP-glucuronyltransferase.

Topics: Amino Acid Sequence; Animals; Biphenyl Compounds; Catalysis; Cattle; Chromatography, Liquid; Electrophoresis, Polyacrylamide Gel; Glucuronosyltransferase; Hymecromone; Male; Microsomes, Liver; Molecular Sequence Data; Naphthols; Nitrophenols; Sequence Homology, Amino Acid; Substrate Specificity

Species difference in glucuronidation of morphine was studied using mice, rats, guinea pigs and rabbits in vivo and in vitro. Morphine-3-glucuronide (M-3-G) and morphine-6-glucuronide (M-6-G) were determined by high-performance liquid chromatography. M-3-G was the major urinary metabolite of morphine in all these animal species. However, a remarkable species difference was observed in the urinary excretion of the M-6-G. Excretion ratios of the M-3-G to M-6-G were approximately 4:1 and 50:1 in guinea pigs and rabbits, respectively. The urinary excretion of M-6-G in mice and rats was too small to be determined. On the other hand, the ratios of uridine diphosphate-glucuronyltransferase (UDPGT) activities toward 3- and 6-hydroxyl groups of morphine in liver microsomes of mice, rats, guinea pigs and rabbits were approximately 300:1, 90:1, 4:1 and 40:1, respectively. Ratios of two morphine UDPGT activities in the liver microsomes of guinea pigs and rabbits, thus, reflected those of urinary excretion of morphine glucuronides.

Topics: Animals; Biotransformation; Biphenyl Compounds; Chromatography, High Pressure Liquid; Glucuronates; Glucuronosyltransferase; Guinea Pigs; In Vitro Techniques; Liver; Male; Mice; Mice, Inbred Strains; Microsomes, Liver; Morphine; Morphine Derivatives; Nitrophenols; Rabbits; Rats; Rats, Inbred Strains; Species Specificity

Species difference in codeine uridine diphosphate-glucuronyltransferase (UDPGT) activity was studied in liver microsomes of mice, rats, guinea pigs and rabbits. Codeine UDPGT activity was the highest in guinea pigs, followed by that in rabbits, and the lowest in mice and rats among these four animal species. The specific activities of codeine UDPGT in liver microsomes were not correlated well with those toward morphine, 4-nitrophenol, and 4-hydroxybiphenyl in liver microsomes of each of the species. Inducibility of liver microsomal codeine UDPGT activity in rats was examined by pretreatment with phenobarbital and 3-methylcholanthrene and compared with those of other UDPGT activities. The activity was inducible by phenobarbital pretreatment as the activity toward morphine and 4-hydroxybiphenyl. The inducibility of codeine UDPGT activity by phenobarbital pretreatment was not as high as that of morphine UDPGT activity.

Topics: Animals; Biphenyl Compounds; Codeine; Enzyme Induction; Glucuronosyltransferase; Guinea Pigs; In Vitro Techniques; Male; Methylcholanthrene; Mice; Microsomes, Liver; Morphine; Nitrophenols; Phenobarbital; Rabbits; Rats; Rats, Inbred Strains; Species Specificity; Substrate Specificity

Studies on the induction of non-oxygenative detoxication enzymes in mice by anticarcinogenic thionosulfur compounds have been extended to include hepatic and pulmonary UDP-glucuronosyltransferases. Dietary administration of disulfiram and of bisethylxanthogen to female CD-1 mice enhanced microsomal glucuronidation of 4-methylumbelliferone, a characteristic GT1 substrate, and of 4-hydroxybiphenyl, a GT2 substrate. Latency of the activity toward 4-methylumbelliferone was not affected appreciably. Disulfiram also enhanced glucuronidation of 4-nitrophenol. Diethyldithiocarbamate was ineffective under the conditions used. These thionosulfur compounds caused no significant change in beta-glucuronidase activity measured in homogenates of 7 organs.

Topics: Animals; Biphenyl Compounds; Diet; Disulfides; Disulfiram; Ditiocarb; Female; Glucuronates; Glucuronidase; Glucuronosyltransferase; Hymecromone; Lung; Mice; Microsomes; Microsomes, Liver; Nitrophenols; Thiones

Liver microsomes of male Beagle dogs contain a form of UDP-glucuronyltransferase which is capable of conjugating digitoxin and its cleavage products digitoxigenin-bisdigitoxoside and digitoxigenin-monodigitoxoside. The highest reaction rates (Vmax 236 pmoles/mg microsomal protein min) were found for digitoxin and digitoxigenin-monodigitoxoside whereas the lowest Km was obtained for digitoxigenin-bisdigitoxoside (29 microM). Digoxin cannot be glucuronidated and digitoxigenin is glucuronidated only in traces. The result may explain the fast digitoxin elimination in dogs. Mutual induction experiments utilizing cardenolides and model substrates of UDP-glucuronyltransferase result in the conclusion that a specific form of UDP-glucuronyltransferase is responsible for glucuronidating digitoxigenin glycosides.

Topics: Animals; Biphenyl Compounds; Digitoxigenin; Digitoxin; Dogs; Glucuronates; Glucuronosyltransferase; In Vitro Techniques; Kinetics; Male; Microsomes, Liver; Nitrophenols; Pregnanediol; Substrate Specificity; Testosterone

Topics: Animals; Biphenyl Compounds; Glucuronates; Glucuronic Acid; Liver; Male; Nitrophenols; Rats; Rats, Inbred Strains; Sulfates

The effect of polyriboinosinic acid-polyribocytidylic acid [poly(I).poly(C)] on glucuronyltransferase activities toward 4-nitrophenol and 4-hydroxybiphenyl in liver microsomes of Wistar rats was examined by its single or co-administration with 3-methylcholanthrene and phenobarbital. The increased 4-nitrophenol glucuronyltransferase activity by treatment with 3-methylcholanthrene was significantly suppressed following the co-administration with poly(I).poly(C), although the activity was not affected by the treatment with poly(I).poly(C) alone. In addition, 4-hydroxybiphenyl glucuronyltransferase activity decreased or tended to decrease by the treatment with poly(I).poly(C) alone, and the activity induced by phenobarbital was strikingly decreased following the co-administration with poly(I).poly(C). This result suggested that poly(I).poly(C) comprehensively decrease the induction of glucuronyltransferases regardless of their multiple forms. Furthermore, contents of cytochromes P-450 and b5 were also decreased by the treatment with poly(I).poly(C) alone or the co-administration with the inducers. Concomitantly, arylhydrocarbon hydroxylase and benzphetamine N-demethylase activities were significantly decreased by the treatment alone or the co-administration with the inducers. These findings supported a view that the suppressive effect of poly(I).poly(C) may be derived from the prevention of de novo synthesis of the apoprotein of the enzymes and/or the increased degradation.

Topics: Animals; Biphenyl Compounds; Cytochrome b Group; Cytochrome P-450 Enzyme System; Cytochromes b5; Enzyme Induction; Glucuronosyltransferase; Heme Oxygenase (Decyclizing); In Vitro Techniques; Interferon Inducers; Male; Methylcholanthrene; Microsomes, Liver; Mixed Function Oxygenases; Nitrophenols; Poly I-C; Rats; Rats, Inbred Strains