The role of cryoprotective agents as hydroxyl radical scavengers

The classic cryoprotective agents dimethylsulfoxide and glycerol are hydroxyl radical scavengers. In addition the cryoprotective agents tetramethylurea, dimethylformide, dimethylurea and monomethylurea act as hydroxyl radical scavengers as shown by the inhibition of ethylene production from methional and the inhibition of methane production from dimethylsulfoxide. Both cryoprotection and scavenger efficiency decrease in the same order within a homologous series: tetramethylurea > dimethylurea > monomethylurea. Urea does not act as a hydroxyl radical scavenger and urea is not a cryoprotective agent. Thus cryoprotection may involve scavengers in the prevention of membrane damage by hydroxyl radicals.