Monochloramine produces reactive oxygen species in liver by converting xanthine dehydrogenase into xanthine oxidase.

In the present study, we assessed the influence of monochloramine (NH(2)Cl) on the conversion of xanthine dehydrogenase (XD) into xanthine oxidase (XO) in rat liver in vitro. When incubated with the partially purified cytosolic fraction from rat liver, NH(2)Cl (2.5-20 microM) dose-dependently enhanced XO activity concomitant with a decrease in XD activity, implying that NH(2)Cl can convert XD into the reactive oxygen species (ROS) producing form XO.

Effects of antirheumatic gold compounds on the conversion of xanthine dehydrogenase to oxidase in rabbit liver cytosol in vitro.

Effects of auranofin (AUR), aurothioglucose (AuTG) and aurothiomalate (AuTM) on the conversion of xanthine dehydrogenase (XD) to oxidase (XO) in the cytosolic fraction from rabbit liver were examined. AUR had no effect on the conversion of XD to XO at concentrations up to 50 microM, whereas at concentrations ranging from 10 to 25 microM, AuTG and AuTM induced the conversion of XD to XO. The constituents of AuTG and AuTM, aurous ion (Au+), but not mercaptosuccinic acid and 1-thio-beta-D-glucose, converted XD to XO in a similar degree to AuTG and AuTM.