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    Establishment of a novel in vitro system for studying the interaction of xenobiotic metabolism of liver and intestinal microflora.
        
        Arch. Toxicol. 74, 379-387 (2000)
    
    
    
	    We developed a new two-chamber system for the coculture of hepatocytes and fecal microflora under aerobic and anaerobic conditions, respectively, to investigate the sequential metabolism of chemicals by the liver and microflora in vitro. The culture device consisted of two chambers separated by a permeable polycarbonate membrane. In the aerobic compartment, hepatocytes were cultivated as a monolayer on the membrane and in the anaerobic compartment fecal microflora as a suspension. To characterize the metabolic capacity of the microflora and hepatocytes, various marker enzymes were studied. Azoreductase, nitroductase, beta-glucuronidase, beta-glucosidase and sulphatase were tested in the microflora of the feces from three volunteers who had had significantly different eating habits for years (daily meat, mixed diet, vegetarian). The microflora exhibited significant activities and the various enzymes differed only moderately in the samples from the three volunteers. For rat hepatocytes the activities of various cytochrome P450 forms and conjugating enzymes served as markers. The enzyme activities were tested in the coculture system during a 4-h culture period intended for the test protocol. Deethylation of ethoxycoumarin and 2alpha-, 6beta- and 16alpha-hydroxylation of testosterone decreased by about 30%, 25%, 40% and 20%, respectively, while there was no loss of glucuronidation and sulphonation of 3-OH-benzo(a)pyrene nor of glutathione conjugation of 1-chloro-2,4-dinitrobenzene during the 4-h culture period. The activities of the tested hepatic phase I and II enzymes were not changed after coculture of the hepatocytes with the microflora for 4 h. The applicability of the in vitro system for studying the metabolic interaction of liver and microflora was demonstrated using 7-ethoxycoumarin and the developmental drug EMD 57033, a thiadiazinon derivative from Merck KGaA, as model compounds. Both compounds were oxidized and conjugated by liver cells. In the coculture of hepatocytes and fecal microflora the resulting glucuronides and sulphoconjugates were split by hydrolytic enzymes of the intestinal microflora.
	
	
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        Publication type
        Article: Journal article
    
 
    
        Document type
        Scientific Article
    
 
     
    
    
        Keywords
        coculture system; hepatocytes; intestinal microflora; drug metabolism; 7-ethoxycoumarin; MICROSOMAL CYTOCHROME-P-450; UDP-GLUCURONYLTRANSFERASE; REDUCTIVE ENZYMES; RAT HEPATOCYTES; CARCINOGENS; DIETARY; FLORA; HYDROXYLATION; PURIFICATION; MUTAGENS
    
 
     
    
    
        Language
        english
    
 
    
        Publication Year
        2000
    
 
     
    
        HGF-reported in Year
        0
    
 
    
    
        ISSN (print) / ISBN
        0340-5761
    
 
    
        e-ISSN
        1432-0738
    
 
    
     
     
	     
	 
	 
    
        Journal
        Archives of Toxicology
    
 
	
    
        Quellenangaben
        
	    Volume: 74,  
	    Issue: 7,  
	    Pages: 379-387 
	    
	    
	
    
 
    
         
        
            Publisher
            Springer
        
 
         
	
         
         
         
         
         
	
         
         
         
    
         
         
         
         
         
         
         
    
        Reviewing status
        Peer reviewed
    
 
     
     
     
     
     
     	
    
        PubMed ID
        11043493
    
    
    
        WOS ID
        WOS:000089510900005
    
    
        Scopus ID
        0033826022
    
    
        Erfassungsdatum
        2001-12-31