Superoxide dismutase (SOD, E.C.1.15.1.1) was assayed by the method of
Marklund and Marklund (1974). Catalase (E.C.1.11.1.6) and glutathione peroxidase
(GSH-Px, E.C.1.11.1.9) activities were determined by the method of Giri et al. (1996)
and Flohe and Gunzler (1984) respectively.