Studies of the arylhydroxylation of monochlorophenylureas in the isolated perfused rat liver

Abstract

Biotransformation studies with phenylurea and the three isomers of monochlorophenylurea were performed using an isolated perfused rat-liver preparation. In the perfusate and the bile, ring-hydroxylation was detected only with phenylurea and with o- and m-chlorophenylurea, and yielded the corresponding p-hydroxylated compounds in each case, while with p-chlorophenylurea no ring hydroxylation was observed at the ortho or meta position. Similar results were obtained with the arylhydroxylation of the herbicide monolinuron (3-(4-chlorophenyl)-1-methoxy-1-methylurea) in the perfused rat liver. In contrast, studies of monolinuron biotransformation in vivo in rats, pigs and hens showed that ring hydroxylation at the ortho or meta position was the main degradation step. The possible reasons for the difference in biotransformation in vivo and in vitro are discussed.