Abstract
Epidemiological studies concerning on the therapy of antioxidants are not fully successful, despite the prove of oxidative stress. Reactive oxygen species (ROS) have a great importance in signalization and neutralisation of bacteries, yeasts, parasites, viruses with the help of leukocytes and tumor cells by NK cells.
The balance between free radikals and antioxidants is complex and very carefully regulated. The disbalance of this system leeds to the disturbance of homeostasis.
Therefore the application of weak prooxidants is sometimes useful for the prevention of deseases (Halliwel, 2013). Oxidative stress is characterised by the predominance of free radicals above the antioxidative defence.