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PubMed1995

Metabolism of polychlorinated phenols by Pseudomonas cepacia AC1100: determination of the first two steps and specific inhibitory effect of methimazole.

Resting cells of 2,4,5-trichlorophenoxyacetic acid-grown Pseudomonas cepacia AC1100 metabolize both dichlorophenols, such as 2,4-dichlorophenol, 2,6-dichlorophenol, 3,4-dichlorophenol, and 3,5-dichlorophenol, and more highly substituted phenols, such as 2,4,6-trichlorophenol and pentachlorophenol, to the corresponding chlorohydroquinones. The first hydroxylation occurs in the para position of the phenol regardless of whether this position is replaced by a chlorine substituent. The first evidence leading to the characterization of para-hydroxylase as a flavin-containing enzyme is provided by the inhibitory effect of methimazole, an alternate substrate for this monooxygenase, on the degradative ability of the strain. In a second step, with tetrachlorohydroquinone, trichlorohydroxyquinone was isolated and completely characterized. Trichlorohydroxyquinone was also obtained from tetrachloroquinone. Incubation of the cells in the presence of an external source of NADPH prevents the further degradation of tetrachlorohydroquinone, suggesting that the quinone derived from the two-electron oxidation of the hydroquinone is more likely the substrate for the second hydroxylation.

Burkholderia cepacia↗
PubMed1997

Purification and characterization of 2,6-dichloro-p-hydroquinone chlorohydrolase from Flavobacterium sp. strain ATCC 39723.

The biochemistry of pentachlorophenol (PCP) degradation by Flavobacterium sp. strain ATCC 39723 has been studied, and two enzymes responsible for the conversion of PCP to 2,6-dichloro-p-hydroquinone (2,6-DiCH) have previously been purified and characterized. In this study, enzymatic activities consuming 2,6-DiCH were identified from the cell extracts of strain ATCC 39723. The enzyme was purified to apparent homogeneity by a purification scheme consisting of seven steps. Gel filtration chromatography showed a native molecular weight of about 40,000, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed a single protein of 42,500 Da. The purified enzyme converted 2,6-DiCH to 6-chlorohydroxyquinol (6-chloro-1,2,4-trihydroxybenzene), which was easily oxidized by molecular oxygen and hard to detect. The end product, 6-chlorohydroxyquinol, was detected only in the presence of a reductase and NADH in the reaction mixture. The enzyme dechlorinated 2,6-DiCH but not 2,5-DiCH. The enzyme required Fe2+ for activity and was severely inhibited by metal chelating agents. The optimal conditions for activity were pH 7.0 and 40 degrees C. The Kcat for 2,6-DiCH was 35 microM, and the kcat was 0.011 s-1.

Biodegradation, Environmental↗
PubMed2006

Mechanism of growth inhibition by free bile acids in lactobacilli and bifidobacteria.

The effects of the free bile acids (FBAs) cholic acid (CA), deoxycholic acid (DCA), and chenodeoxycholic acid on the bioenergetics and growth of lactobacilli and bifidobacteria were investigated. It was found that these FBAs reduced the internal pH levels of these bacteria with rapid and stepwise kinetics and, at certain concentrations, dissipated DeltapH. The bile acid concentrations that dissipated DeltapH corresponded with the MICs for the selected bacteria. Unlike acetate, propionate, and butyrate, FBAs dissipated the transmembrane electrical potential (DeltaPsi). In Bifidobacterium breve JCM 1192, the synthetic proton conductor pentachlorophenol (PCP) dissipated DeltapH with a slow and continuous kinetics at a much lower concentration than FBAs did, suggesting the difference in mode of action between FBAs and true proton conductors. Membrane damage assessed by the fluorescence method and a viability decrease were also observed upon exposure to CA or DCA at the MIC but not to PCP or a short-chain fatty acid mixture. Loss of potassium ion was observed at CA concentrations more than 2 mM (0.4x MIC), while leakage of other cellular components increased at CA concentrations more than 4 mM (0.8 x MIC). Additionally, in experiments with membrane phospholipid vesicles extracted from Lactobacillus salivarius subsp. salicinius JCM 1044, CA and DCA at the MIC collapsed the DeltapH with concomitant leakage of intravesicular fluorescent pH probe, while they did not show proton conductance at a lower concentration range (e.g., 0.2x MIC). Taking these observations together, we conclude that FBAs at the MIC disturb membrane integrity and that this effect can lead to leakage of proton (membrane DeltapH and DeltaPsi dissipation), potassium ion, and other cellular components and eventually cell death.

Bifidobacterium↗
PubMed1968

Inhibition of membrane transport in Streptococcus faecalis by uncouplers of oxidative phosphorylation and its relationship to proton conduction.

We studied the effect of compounds that uncouple oxidative phosphorylation on membrane function in Streptoccocus faecalis, an organism which relies upon glycolysis for the generation of metabolic energy. At low concentrations (ranging from 10(-7) to 10(-4)m), tetrachlorosalicylanilide, tetramethyldipicrylamine, carbonylcyanide m-chlorophenylhydrazone, pentachlorophenol, and dicoumarol strongly inhibited energy-dependent transport of rubidium, phosphate, and certain amino acids. However, these compounds had little effect on the generation of adenosine triphosphate via glycolysis or on its utilization for the synthesis of macromolecules. They also did not seriously inhibit uptake of those monosaccharides and amino acids which do not require concurrent metabolism. It is proposed that the uncouplers interfere with the utilization of metabolic energy for membrane transport. The uncouplers accelerated the translocation of protons across the cytoplasmic membrane. It appears that a proton-impermeable membrane is required for transport, perhaps, because a proton gradient is involved in the coupling of metabolic energy to the translocation of substrates across the membrane.

Adenosine Triphosphate↗
PubMed1976

The respiratory metabolism of Mycobacterium lepraemurium.

The respiratory metabolism of Mycobacterium lepraemurium isolated from Sprague-Dawley rats lepromata using several substrates was investigated. None of the intermediates of the glycolysis cycle as well as of the tricarboxylic acid cycle except succinate was oxidized by purified whole suspensions of M. lepraemurium. Likewise, many sulfur compounds such as cystine, thiourea, thioacetate, thiodiglycol, mercaptoact and some sulfhydryl compounds, e.g., cysteine, dithioerythritol, dithiorthritol, and penicillamine were readily oxidized by murine bacillary suspensions, whereas thioglycolate, thioglucose, and reduced glutathione were oxidized at a slow rate. Succinate was not or was very poorly oxidized by normal cells probably because of impermeability of the cell wall but the addition of succinate to the cell suspensions frozen for 1 min at -40 degrees C considerably enhanced oxygen uptake over the endogenous value. The oxidation of succinate was unaffected by inhibitors rotenone, atabrine, and amytal but was markedly inhibited by thenoyltrifluoroacetone, antimycin A, 2-N-heptyl-4-hydroxyquinoline-N-oxide, and cyanide. The thiol-binding agents, p-hydroxymercuribenzoate and N-ethylmaleimide were also effective inhibitors of succinate oxidation but the process was not affected by uncouplers dinitrophenol, dibromophenol, pentachlorophenol, and carbonyl-cyanide-m-chlorophenylhydrazone. The results indicated that succinate oxidation by M. lepraemurium was mediated by oxidative enzymes involving an electron transport chain with oxygen as the terminal electron acceptor.

Antimycin A↗
PubMed1976

The metabolism of higher chlorinated benzene isomers.

The metabolism of the isomeric tri- and tetrachlorobenzene isomers, penta- and hexachlorobenzene was investigated in the rabbit. The major urinary metabolites of the isomeric tri- and tetrachlorobenzenes were identified as the corresponding tri- and tetrachlorophenols whose structures were confirmed by chromatographic analyses. The genesis of the formation of metabolites is discussed in terms of their possible arene oxide intermediates in which the NIH shift of a chlorine atom is observed in the oxidation of many of the isomers. Pentachlorobenzene is metabolized to give both pentachlorophenol and a dechlorination-hydroxylation product which was identified as 2,3,4,5-tetrachlorophenol. The hexachlorobenzene substrate did not give any phenolic metabolites.

Animals↗
PubMed1981

Energy coupling mechanisms in host-grown Mycobacterium lepraemurium.

Energy coupling mechanisms of Mycobacterium lepraemurium isolated from Sprague-Dawley rats lepromata were investigated. Cell-free extracts catalyzed phosphorylation coupled to the oxidation of generated NADH, added NADH, and succinate yielding P/O ratios of approximately 0.8, 0.6, and 0.4, respectively. Ascorbate oxidation alone or in the presence of cytochrome c or N,N,N',N'-tetramethyl-p-phenylenediamine was not coupled to ATP synthesis. The oxidative phosphorylation was completely uncoupled by 2,4-dinitrophenol, 2,6-dibromophenol, pentachlorophenol, m-chlorocarbonylcyanide phenylhydrazone, dicumarol, and gramicidin at concentrations which did not cause any inhibition of oxygen uptake. While the NADH oxidation and associated phosphate esterification was markedly sensitive to rotenone and other flavoprotein inhibitors, these inhibitors had no effect, however, on the phosphorylation coupled to succinate oxidation. The respiratory chain inhibitors such as antimycin A or 2-n-heptyl-4-hydroxyquinoline-N-oxide, and cyanide were the potent inhibitors of the phosphorylation associated with the oxidation of NADH and succinate. The ATP formation coupled to the oxidation of NADH and succinate was also inhibited by oligomycin as well as by the thiol-binding agents, p-hydroxymercuribenzoate and N-ethylmaleimide. The results indicated that NADH and succinate oxidation by in vivo grown M. lepraemurium was mediated by oxidative enzymes involving first and second energy coupling sites.

Adenosine Triphosphate↗
PubMed1994

Carrier-mediated transport of lipoxin A4 in human neutrophils.

Lipoxins and other eicosanoids display potent and selective biological effects on leukocytes. In this study, we utilized radiolabeled lipoxin A4 ([3H]LXA4) to investigate whether carrier-mediated transport of LXA4 might occur in human neutrophils. At a concentration of 5 nM, uptake of [3H]LXA4, above that due to specific binding to receptors, amounted to approximately 0.6 fmol.10(6) cells-1.min-1. This influx was sensitive to a number of anionic inhibitors, including 3,5-diiodosalicylic acid (K0.5 12 microM), pentachlorophenol (K0.5 25 microM), alpha-cyano-beta-(1-phenylindol-3-yl) acrylic acid, and the organomercurial agents mersalyl (K0.5 110 microM) and p-hydroxy-mercuribenzoate. Influx, which was Na+ and membrane voltage independent, exhibited a striking dependence on pH (negative log of dissociation 5.9), results compatible with an H+ + LXA4 anion cotransport system. The LXA4 carrier did not appear to interact with arachidonic acid, prostaglandin E2, 15(S)-hydroxy-(5Z,8Z,11Z,13E)-eicosatetraenoic acid, or the leukotrienes B4, C4, and D4. Moreover, transport activity was not observed in human erythrocytes, lymphocytes, or platelets, but it was inducible in HL-60 cells on differentiation by exposure to retinoic acid. These findings represent the identification and initial characterization of a novel carrier-mediated pathway in human neutrophils that facilitates transport of LXA4 into cells.

Biological Transport↗
PubMed2006

Cluster analysis of the dermal permeability and stratum corneum/solvent partitioning of ten chemicals in twenty-four chemical mixtures in porcine skin.

Assumptions based on absorption from single solvent systems may be inappropriate for risk assessment when chemical mixtures are involved. We used K-means and hierarchical cluster analyses to identify clusters in stratum corneum partitioning and porcine skin permeability datasets that are distinct from each other based on mathematical indices of similarity and dissimilarity. Twenty-four solvent systems consisting of combinations of water, ethanol, propylene glycol, methyl nicotinate and sodium lauryl sulfate were used with 10 solutes, including phenol, p-nitrophenol, pentachlorophenol, methyl parathion, ethyl parathion, chlorpyrifos, fenthion, simazine, atrazine and propazine. Identifying the relationships between solvent systems that have similar effects on dermal absorption formed the bases for hypotheses generation. The determining influence of solvent polarity on the partitioning data structure supported the hypothesis that solvent polarity drives the partitioning of non-polar solutes. Solvent polarity could not be used to predict permeability because solvent effects on diffusivity masked the effects of partitioning on permeability. The consistent influence of the inclusion of propylene glycol in the solvent system supports the hypothesis that over-saturation due to solvent evaporation has a marked effect on permeability. These results demonstrated the potential of using cluster analysis of large datasets to identify consistent solvent and chemical mixture effects.

Animals↗
PubMed1989

Indoor air contamination with polychlorinated dibenzo-p-dioxins and dibenzofurans.

Pentachlorophenol (PCP), used extensively for wood preservative purposes, contains trace amounts of polychlorinated dibenzodioxins (PCDDs) and-dibenzofurans (PCDFs) as contaminants. Residues of these compounds are present on the surface and sub-surface of the treated wood. These contaminants have the potential to wear (or migrate) away or volatilize from the wood surface and become entrained in ambient air or dust particles, and thus becoming available for human contact. During the early sixties several day nursery facilities were built with PCP-treated wood in the northern part of West Germany. In this paper we describe the indoor air monitoring data in these kindergarten buildings and the associated possible long-term health risk. The indoor ambient air was found to be contaminated with highly toxic PCDDs/PCDFs at pg/m3 levels. HxCDDs, HpCFs and OCDDs/OCDFs congeners were the major contaminants.

Air Pollutants↗
PubMed2006

Effects of organochlorine pesticides on interleukin secretion from lymphocytes.

Organochlorine pesticides have been used worldwide primarily as insecticides. Due to their chemical stability, they often persist in the environment long after their use has ceased. In a previous study, we found that six organochlorine compounds (alpha-chlordane, gamma-chlordane, 4,4'-DDT, heptachlor, oxychlordane, and pentachlorophenol (PCP)), at concentrations of 5 microM, were able to significantly decrease the ability of highly purified human natural killer (NK) cells to lyse tumor cells after exposures, ranging from 1 hour to 6 days. However, if T cells were present with the NK cells (T/NK cells), loss of lytic function was seen only with oxychlordane and PCP. The purpose of the current study is to begin to investigate the mechanism by which T cells may be blocking the negative effects of some organochlorine compounds on NK cell function. Here, we investigated the hypothesis that T cells could produce significant levels of NK-stimulatory interleukin(s) (ILs), and that this may account for the decreased inhibition seen with organochlorine exposures when T cells were present. Secretion of four cytokines that have a demonstrated capacity to influence NK function, and/or are secreted by T cells, was measured (IL-2, IL-4, IL-10, IL-12). We measured both the baseline levels of ILs and the effects of organochlorine compound on IL secretion in T/NK cells. The results showed that baseline levels of the NK-stimulatory IL, IL-12, were 898 +/- 264 pg/mL at 24 hours and IL-10 levels were 564 +/- 337 pg/mL. In contrast, IL-2 levels were 14 +/- 10 pg/mL, and IL-4 levels were 3 +/- 2 pg/mL at 24 hours. The two compounds that retained their capacity to decrease NK lytic function in T/NK cells, oxychlordane (5 microM) and PCP (5 and 10 microM), were able to either decrease the secretion of NK-stimulatory ILs (IL-2, IL-12 and/or IL-10) and/or increase secretion of the NK-inhibitory cytokine, IL-4, at each length of exposure tested.

Adult↗
PubMed1991

Chloracne caused by ingestion of olive oil contaminated with PCDDs and PCDFs.

1. All members of a Spanish family (father, mother and six children) developed chloracne. 2. The causative agent was found to be the family's stock of olive oil, which had become contaminated with polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), pentachlorophenol, and hexachlorobenzene. 3. The more highly chlorinated PCDDs, in particular octachlorodibenzo-p-dioxin, were the predominant congeners in the oil. 4. Three members of the family exhibited either an overt or a sub-clinical disturbance of kidney function. The father also had a chronic respiratory problem. These changes could not be unequivocally attributed to the PCDDs. 5. Experimental toxicity of the oil was limited to the development of an hepatic porphyria in mice. 6. A serum sample, taken 5 years after consumption of the oil ceased, contained high levels of the PCDDs and PCDFs. Extrapolation back to ingested dose was used to validate dosage estimates. 7. The use of toxicity equivalence factors (TEFs) provided estimates of cumulative dosage to produce chloracne as 0.13-0.31 micrograms 2378-TCDD kg-1 (using EPA TEFs) or 6.7-16 micrograms 2378-TCDD kg-1 (using Nordic/NATO TEFs). 8. This is the first incident in which human toxicity is related primarily to ingestion of PCDDs and for which estimates of dosage can be made.

Acne Vulgaris↗
PubMed1992

Sulphur derivative of hexachlorobenzene in human urine.

Pentachlorothiophenol, a sulphur derivative of the widespread environmental pollutant hexachlorobenzene (HCB) has been detected and quantified in the urine of a human general population with high body burden of HCB. The sulphur derivative was analysed by GLC-MS as pentachlorothioanisole (PCTA) after hydrolysis and methylation of the respective conjugate and was found in 100% of the samples (n = 40) with a mean concentration of 1.85 +/- 0.98 ng ml-1 (mean +/- s.d., range 0.58-4.50 ng ml-1). No correlation with urinary pentachlorophenol (PCP) and no sex-related differences were found. The derivative may originate from the biotransformation of HCB stored in tissues and may be a useful maker of HCB metabolism in humans.

Biotransformation↗
PubMed1993

Analysis of polychlorinated dioxins and furans in samples of the toxic oil syndrome.

1 Polychlorinated dioxins (PCDDs) and furans (PCDFs) are known to produce a wide range of toxic effects. 2 PCDDs and PCDFs are typical contaminants of chlorinated phenols, and pentachlorophenol and related compounds have been shown to be widely distributed among selected oil samples taken from the 1981 Spanish toxic oil epidemic. 3 Six control and eight case oil samples were analysed using GC/MS for PCDDs and PCDFs. Only small concentrations, normally below 1 ng g-1, of the higher chlorinated PCDDs and PCDFs were detected. There were no statistical differences between the case and control oils. 4 These levels seem to be too low to elicit toxic effects, although they could be enough to potentiate the toxicity of other xenobiotics present in the oils. However, it is uncertain whether the levels of these compounds measured in 1990 reflect the levels present when the oils were consumed in 1981, or whether or not the levels measured in crude oils are representative of fried oils.

Brassica↗
PubMed2004

Cell-based assay for the detection of chemically induced cellular stress by immortalized untransformed transgenic hepatocytes.

BACKGROUND: Primary hepatocytes, one of the most widely used cell types for toxicological studies, have a very limited life span and must be freshly derived from mice or even humans. Attempts to use stable cell lines maintaining the enzymatic pattern of liver cells have been so far unsatisfactory. Stress proteins (heat shock proteins, HSPs) have been proposed as general markers of cellular injury and their use for environmental monitoring has been suggested. The aim of this work is to develop a bi-transgenic hepatocyte cell line in order to evaluate the ability of various organic and inorganic chemicals to induce the expression of the HSP70 driven reporter gene. We previously described transgenic mice (Hsp70/hGH) secreting high levels of human Growth Hormone (hGH) following exposure to toxic compounds in vivo and in vitro in primary cultures derived from different organs. In addition, we also reported another transgenic model (AT/cytoMet) allowing the reproducible immortalization of untransformed hepatocytes retaining in vitro complex liver functions. RESULTS: The transgenic mouse line Hsp70/hGH was crossed with the AT/cytoMet transgenic strain permitting the reproducible immortalization of untransformed hepatocytes. From double transgenic animals we derived several stable hepatic cell lines (MMH-GH) which showed a highly-differentiated phenotype as judged from the retention of epithelial cell polarity and the profile of gene expression, including hepatocyte-enriched transcription factors and detoxifying enzymes. In these cell lines, stresses induced by exposure to inorganic [Sodium Arsenite (NaAsO2) and Cadmium Chloride (CdCl2)], and organic [Benzo(a)Pyrene (BaP), PentaChloroPhenol (PCP), TetraChloroHydroQuinone (TCHQ), 1-Chloro-2,4-DiNitro-Benzene (CDNB)] compounds, specifically induced hGH release in the culture medium. CONCLUSIONS: MMH-GH, an innovative model to evaluate the toxic potential of chemical and physical xenobiotics, provides a simple biological system that may reduce the need for animal experimentation and/or continuously deriving fresh hepatocytes.

Animals↗
PubMed1997

Cytotoxicity of organochlorine pesticides and lipid peroxidation in isolated rat hepatocytes.

The cytotoxicity and lipid peroxidation of pesticides containing a halogen group were examined in isolated rat hepatocytes. We examined 9 pesticides of 3 different representative chemical families, chlorinated aromatic fungicides (pentachlorophenol (PCP), pentachloronitrobenzene (PCNB), chlorothalonil, fthalide), polyhaloalkylated thio fungicides (dichlofluanid, captan) and diphenyl ether herbicide (2,4-dichlorophenyl 4-nitrophenyl ether (NIP), 4-nitrophenyl2,4,6-trichlorophenyl ether (CNP), chlomethoxynil). The contents of the hydroperoxides in phospholipid, phosphatidylcholine hydroperoxide (PCOOH) and phosphatidylethanolamine hydroperoxide (PEOOH) were determined by the HPLC-chemiluminescence (CL-HPLC) method, which is sensitive and specific for lipid hydroperoxide. Chlorothalonil, dichlofluanid and captan were the most potent cytotoxicants evaluated by lactate dehydrogenase (LDH) leakage. PCP, NIP and CNP exhibited intermediate cytotoxicity. PCNB, fthalide and chlomethoxynil showed low cytotoxicity. The cellular phospholipid hydroperoxide (PCOOH and PEOOH) levels were remarkably increased by chlorothalonil (PCOOH, 23 times and PEOOH, 7 times), dichlofluanid (PCOOH, 523 times and PEOOH, 22 times) and captan (PCOOH, 518 times and PEOOH, 16 times) as compared with the control group. The PCOOH content was slightly increased by PCP (4.8 times) and NIP (6.3 times), whereas the other 4 pesticides did not change the phospholipid hydroperoxide level. Severe cytotoxicity was observed with a remarkable increase of phospholipid hydroperoxide by chlorothalonil, dichlofluanid and captan.

Animals↗
PubMed2006

Effects of possible endocrine disrupting chemicals on bacterial component-induced activation of NF-kappaB.

Endocrine disrupting chemicals (EDCs) have a possibility to exacerbate infectious diseases because EDCs disturb the human immune system by interfering with endocrine balance. To assess the influence of EDCs on the innate immune function of macrophages, we investigated the effects of thirty-seven possible endocrine disruptors on lipopolysaccharide (LPS)- or bacterial lipopeptide (Pam3CSK4)-induced activation of nuclear factor kappa B (NF-kappaB). Alachlor, benomyl, bisphenol A, carbaryl, kelthane, kepone, octachlorostyrene, pentachlorophenol, nonyl phenol, p-octylphenol and ziram inhibited both LPS- and Pam3CSK4-induced activation of NF-kappaB. Simazine inhibited only LPS-induced activation. A strong inhibitory effect was observed with ziram and benomyl. On the other hand, diethylhexyl adipate and 4-nitrotoluene tended to enhance the activation induced by Pam3CSK4 and LPS, respectively. Aldicarb, amitrole, atrazine, benzophenone, butyl benzyl phthalate, 2,4-dichlorophenoxy acetic acid, dibutyl phthalate, 2,4-dichlorophenol, dicyclohexyl phthalate, diethylhexyl phthalate, diethyl phthalate, dihexyl phthalate, di-n-pentyl phthalate, dipropyl phthalate, malathion, methomyl, methoxychlor, metribuzin, nitrofen, permethrin, trifluralin, 2,4,5-trichlorophenoxyacetic acid and vinclozolin had no significant effects at 100 microM. These results indicate that some agrochemicals have the potential to inhibit macrophage function and suggest that endocrine disruptors may influence the development of bacterial infections.

Animals↗
PubMed1986

Mutagenicity of some hydroxylaminotoluene derivatives towards Salmonella typhimurium in esterification systems.

The mutagenicity of 2-hydroxylamino-4-nitrotoluene (2HA4NT), 4-hydroxylamino-2-nitrotoluene (4HA2NT), 2-hydroxylamino-6-nitrotoluene (2HA6NT) or 4-acetylamino-2-hydroxylaminotoluene (4AA2HAT) towards Salmonella typhimurium strains TA98 and TA100 was investigated in the absence and presence of uridine-5'-diphosphoglucuronic acid (UDPGA), acetyl CoA or 3'-phosphoadenosine-5'-phosphosulfate (PAPS) systems, or S9 mix. None of the hydroxylaminonitrotoluenes (2HA4NT, 4HA2NT or 2HA6NT) were mutagenic in both strains while 4AA2HAT was a base-pair substitution mutagen in the UDPGA and PAPS systems. The indirect mutagenic activity was markedly decreased by omission of microsomal fraction (MCF) or UDPGA from the UDPGA system and by addition of beta-glucuronidase to the system. Similarly, the mutagenic activity was markedly decreased either when 105000 X g supernatant fluid (S105), adenosine triphosphate (ATP) or Na2SO4 was omitted from the PAPS system or when pentachlorophenol (PCP) or aryl sulphatase was added to the system. Moreover, the mutagenic activity in either system was markedly decreased by the addition of glutathione (GSH). These results suggested that two esterifications with glucuronic acid and sulfuric acid may play an important role in the appearance of mutagenic activity of 4AA2HAT.

Animals↗