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We have investigated the potential of piperine for inhibiting the activity of cytochrome P4502B1 and protecting against aflatoxin B1 (AFB1) in V79MZr2B1 (r2B1) cells, i.e. V79 Chinese hamster cells engineered for the expression of rat CYP4502B1. The cells were found to contain high activities of 7-methoxycoumarin demethylase (MOCD). Piperine inhibited MOCD(More)
The effects of piperine, a major ingredient of black pepper, on UDP-glucose dehydrogenase (UDP-GDH) and glucuronidation potentials of rat and guinea pig liver and intestine were studied. Piperine caused a concentration-related strong inhibition of UDP-GDH (50% at 10 microM) reversibly and equipotently, in both tissues. Partially purified rat liver UDP-GDH(More)
A V79 Chinese hamster cell line stably expressing human cytochrome P450 1A1 (CYP1A1) was obtained by chromosomal integration of the human CYP1A1 cDNA under the control of the SV40 early promoter. Chromosomal integration was verified by Southern analysis, and effective transcription of the human CYP1A1 cDNA was demonstrated by Northern analysis. The CYP1A1(More)
V79 Chinese hamster cells were genetically engineered for stable expression of human P450IA2. Full length cDNA, encoding human P450IA2, was inserted into an SV40 early promoter containing eukaryotic expression vector and cointroduced with the selection marker neomycin phosphotransferase (conferring resistance to the neomycin derivative G418) into V79(More)
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7,8-tetrachlorodibenzofuran (TCDF), and benz[a]anthracene (BA) highly induce cytochrome P4501A1, determined by aryl hydrocarbon hydroxylase (AHH) activity, in human hepatoma HepG2 cells within 24 h. AHH activity induced by TCDD and TCDF persists for at least 48 h. In contrast, AHH activity induced by BA(More)
The microsomal cytochrome P-450-dependent aryl hydrocarbon hydroxylase is important in the detoxification of polycyclic hydrocarbons as well as their activation to cytotoxic or carcinogenic derivatives. We have studied compounds that can modify the activity of this enzyme system. Three types of flavones are distinguished on the basis of their effect on the(More)
The study was aimed at determining the genotoxic potential of extractable organic matter (EOM) from ambient air particles PM10 (<10 micrometer) using mammalian cells in culture as test system. Air samples were collected in the course of summer and winter periods in two regions of the Czech Republic representing low and high levels of air pollution, the(More)
The study was aimed at establishing a bioassay for the determination of 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalents (TEQs) in environmental samples. Specifically, development of a rapid cleanup procedure adapted to the needs of the bioassay and simplification of the measurement of its endpoint, the induction of 7-ethoxyresorufin O-deethylase(More)
The expression of xenobiotic-metabolizing enzymes was studied in the human lung tumour cell lines NCI-H322 and NCI-H358. These cells are derived from adenocarcinomas and exhibit features of Clara cells and alveolar type II cells, respectively. Examination of the in vitro activities showed that both cell lines lack UDP-glucuronosyltransferase against the(More)