In animals and humans, after ingestion, natural phenols become part of the xenobiotic metabolism . In subsequent phase II reactions, these activated metabolites are conjugated with charged species such as glutathione , sulfate , glycine or glucuronic acid . These reactions are catalysed by a large group of broad-specificity transferases. UGT1A6 is a human gene encoding a phenol UDP glucuronosyltransferase active on simple phenols.  The enzyme encoded by the gene UGT1A8 has glucuronidase activity with many substrates including coumarins , anthraquinones and flavones .