The Steady State Concentration of Different Biomarkers of Oxidative Stress Reflect Different Types of Oxidative Stress

Abstract

Oxidative stress (OS) is an intuitively defined term that depends on the criterion used to evaluate it. The MARK-AGE consortium recently published a thorough investigation of the age dependence of the OS as determined by the steady state concentrations of different biomarkers of OS. Most biomarkers correlate significantly with almost all the other biomarkers but the correlations were weak. The possibility that all these effects are manifestations of one type of OS has yet to be evaluated. We think that the different biomarkers reflect different types of OS. This conclusion accords with two lines of comparison. (i) the overlapping between the lists of OS, as studied by different biomarkers is very low and (2) MDA appears to be sensitive to both gender and age. Specifically, in women MDA concentration increases in a stepwise fashion at the age of about 50 and, GSH decreased with age apparently simultaneously with the increase of MDA level. By contrast the concentration of both protein carbonyls and nitrotyrosine were the same in men and women and appeared to be independent of age. In conclusion, it appears that different biomarkers reflect different types of OS and that MDA and GSH reflect the same type of OS.