For the SOD assay, 500 lL of separated RBCs was washed three
times with 0.9% w/v cold normal saline and centrifuged for 10 min
at 1500g after each wash. Washed RBCs were mixed with four volumes
of cold, double-distilled water at 4 C for 15 min. The resulting
suspension was centrifuged twice to eliminate all of the cell
membrane material. The haemolysates were used to determine
the SOD activity by using the Ransod kit (Randox Laboratories
Ltd., Northern Ireland, UK). The specific activity of SOD was expressed
in units per gram of haemoglobin (U/g Hb).