2.4. Oxidative stress parameters
2.4.1. Thiobarbituric acid reactive substances (TBARS)
The concentration of TBARS was measured spectrophotometrically, and the
results were expressed as nmol/mL [30].
2.4.2. Superoxide dismutase activity (SOD)
Superoxide dismutase activity was determined spectrophotometrically in
serum samples by measuring the inhibition of the rate of auto-catalytic
adrenochrome formation at 480 nm in a reaction medium containing a final concentration of 1 mmol L
−1
adrenaline (pH 2.0) and 50 mmol L
−1
glycine (pH 10.2) [31],
both from E. Merck, with a pH of 10.0. This reaction was conducted at a constant
temperature of 30
◦
C for 3 min. The enzymatic activity was expressed as superoxide
dismutase units per gram of protein. One unit is defined as the amount of enzyme
that inhibits the rate of adrenochrome formation by 50%.