Inhibition of hydroxyl radical production by lactobionate, adenine, and tempol.

Superoxide and hydroxyl free radicals are strongly implicated in the deleterious effects of reperfusion of grafted organs. Iron ions are critical in the Fenton-like reaction that generates oxygen-free radicals from H2O2. Using the ADP/Fe2+/H2O2 .OH-generating system, we demonstrated that components of an organ-preservation solution (Henri Mondor solution): sodium lactobionate, adenine, and a nitroxide radical: 4-hydroxy-2,2,6,6-tetramethylpiperidine-n-oxyl (TEMPOL), showed unexpected inhibition properties on the production of hydroxyl radicals by complexation of Fe2+ for lactobionate and nitroxide or Fe3+ for adenine. This inhibition was 75.5% at 12 mM lactobionate. Moreover, a complete inhibition was observed at 50 mM. At 0.25 mM adenine, the reduction was 14.8% (maximum effect: 34.1%). Henri Mondor solution, at an identical adenine and lactobionate concentration, inhibited the radical production by 91.5%, indicating an additive effect. Nitroxide totally inhibited .OH production by the ADP/Fe2+/H2O2 system (maximum effect: 95.6%) and partially the production by an O2.- generating system (maximum effect: 74.8%). Thus, the association of these three components in preservation solutions would be an original method to limit the reperfusion injury observed in isolated ischemic organs.