Requirements for SOD mimics operating in vitro to work also in vivo.

When an efficient SOD mimic operating in vitro is introduced into cells, the following requirements are needed in order that this compound will catalyze O2- dismutation efficiently: it should be non toxic, stable, has a long metabolic half life, does not form ternary complexes with the cell components, its reduced form reacts slowly with molecular oxygen, should be able to cross cell membranes and also to reach lipophilic or hydrophobic regions. Thus, it seems that finding an efficient compound that has high SOD-like activity in vivo will not be easily achieved.