Antioxidants are molecules that work against the oxidation of the cells. They are stable enough to offer electrons to free radicals and thus help neutralize them. They provide protection against the damaging effects of free radicals.
According to the study Nishida et al., (2007), astaxanthin is the most powerful antioxidant known to science until this moment. Its power comes from its unique structure that allows it to quench free radicals in the inner and outer layer of the cell membrane unlike other antioxidants.