Protection against alloxan-induced diabetes by various urea derivatives: relationship between protective effects and reactivity with the hydroxyl radical.

Several urea derivatives (monomethylurea, monoethylurea and diethylurea) give i.p. to mice 30 min before alloxan (75 mg/kg i.v.) were able to prevent the diabetogenic actions of alloxan. Protection by these agents correlated reasonably well with their capacity to react with (scavenge) the hydroxyl radical. Protection did not correlate with the capacity of the above agents to cause a transient hyperglycemia at the point of alloxan administration, which might have also been a potential means of protection. These data extend previously published data on the capacity of hydroxyl radical scavengers to protect against alloxan and add evidence to the concept that the hydroxyl radical, generated within the beta cells, is the species derived from alloxan responsible for the damage to beta cells.