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Xenobiotic Biotransformation
Published in Robert G. Meeks, Steadman D. Harrison, Richard J. Bull, Hepatotoxicology, 2020
The primary type of sulfotransferase involved in xenobiotic biotransformation is that reacting with aryl compounds. At least three forms of aryl sulfotransferase and three forms of hydroxysteroid sulfotransferase have been purified to homogeneity from rat liver. The enzymes are developmentally and hormonally regulated, but apparently are not inducible by PB or 3-MC exposure.
In vitro sulfonation of 7-hydroxycoumarin derivatives in liver cytosol of human and six animal species
Published in Xenobiotica, 2020
Risto O. Juvonen, Olli Pentikäinen, Juhani Huuskonen, Juri Timonen, Olli Kärkkäinen, Aki Heikkinen, Muluneh Fashe, Hannu Raunio
The rate of sulfonation can be measured by assays based on radiometric, absorbance, fluorescence and HPLC-MS detection. In radiometric assay the sulfur atom of transferred sulfone is labeled with 35S, which can be measured precisely and at high sensitivity from the isolated metabolite in an endpoint experimental setup (Paul et al., 2012). The absorbance and fluorescence assays are based on indirect measurement of sulfonation in which the actual substrates and p-nitrophenol sulfate or 4-methyl-7-hydroxycoumarin sulfate are tightly coupled to the regeneration of PAP to PAPS by aryl sulfotransferase IV enzyme. In this coupling reaction sulfates are transformed to absorbing p-nitrophenol or fluorescent 4-methyl-7-hydroxycoumarin. The increase in absorbance or fluorescence can be measured by continuous or endpoint assays; measurement of fluorescence is more sensitive than of absorbance (Chen et al., 2005; Lu et al., 2010). The decrease of fluorescence of 7-hydroxycoumarin or resorufin during sulfonation has also been measured directly. In HPLC-MS assays substrates and the formed metabolites are separated by HPLC and then detected and analyzed by different kinds of MS approaches (Paul et al., 2012).