2.6.3 Measurement of lipid peroxide

0.2 ml of tissue homogenate, 1.5 ml of 20% acetic acid, 0.2 ml of 8.1% sodium dodecyl sulphate and 1.5 ml of 8% thiobarbituric acid were added. The mixture was diluted to 4.0 ml with distilled water and then heated in a water bath (95°C) for 60 min. After cooling the tubes to room temperature, the final volume was increased to 5.0 ml in each tube. Then, the n-butanol:pyridine mixture was added and the contents were vortexed for 2 min. The organic upper layer was taken following centrifugation at 3,000 rpm for 10 min and the optical density was measured at 532 nm against the blank. The quantities of lipid peroxides in brain homogenate were measured in nanomoles of malondialdehyde/min/mg protein (Ohkawa et al., 1979).