There is ample evidence in the literature concerning the labile nature of rat liver xanthine oxidase and its dependence on dietary protein. McQuarrie and Venosa (1) observed a large drop in the enzyme activity when the protein content of the ration was reduced from 25 to 10 per cent. Miller (2) noticed that a 7 day inanition caused a loss of xanthine oxidase activity in rat liver which exceeded...

Xanthine oxidase has been hypothesized to be an important source of biological free radical generation. The enzyme generates the superoxide radical, .O2- and has been widely applied as a .O2- generating system; however, the enzyme may also generate other forms of reduced oxygen. We have applied electron paramagnetic resonance (EPR) spectroscopy using the spin trap 5,5'-dimethyl-1-pyrroline-N-ox...

BACKGROUND Evidence supporting the role of xanthine oxidase in myocardial reperfusion injury is based on studies with pharmacological interventions used to inhibit enzyme function. Controversy exists, however, regarding the true role of xanthine oxidase in reperfusion injury. This study was performed to determine whether xanthine oxidase inhibition limits myocardial injury due to coronary arter...

Allopurinol, the xanthine oxidase inhibitor, is the only drug available for the treatment of gout. We examined the xanthine oxidase inhibitory activity of some commercially available flavonoids such asepigallocatechin, acacatechin, myricetin, naringenin, daidzein and glycitein by virtual screening and in-vitro studies. The interacting residues within the complex model and their contact types we...

The reperfusion of previously ischemic tissue may lead to the formation of highly reactive free radicals that promote tissue injury. Xanthine oxidase has been implicated as one source of these free radicals. We examined the role of xanthine oxidase in brain injury using a cerebrospinal fluid compression model of global cerebral ischemia with 15 minutes of ischemia and 4 hours of reperfusion. Se...

Oxidative stress is an important signal for apoptosis to start. So far the mitochondrial respiratory chain has been considered as the major, if not the only, cause of such stress. Here we report that this is not the case. Xanthine oxidase, a O2(-) and H2O2 generating enzyme which is important in causing significant oxidative stress in the cytosol, is also present in the mitochondrial fraction o...

We previously showed oxidative damage and edema within skeletal muscle after contractile claudication. To investigate the sources of this oxidative damage in the gastrocnemius muscle, we administered allopurinol (Allo, to inhibit xanthine oxidase) and cyclophosphamide (Cyclo, to deplete neutrophils) before inducing contractile claudication in male Sprague Dawley rats. Contractile claudication (...

Various purine analogs active as carcinostatic agents have previously been shown to act as po tent inhibitors of xanthine oxidase in vitro in both homogenate and isolated enzyme systems (4, 5). 8-Azaguanine (8-AG) has been demonstrated to be an in vitro inhibitor of both xanthine oxidase and uricase (4, 9). Elion et al. have reported that 6mercaptopurine (6-MP) is a substrate for xanthine oxida...