Title : Interrelations between the steady state plasma concentrations of oxidative stress biomarkers and low molecular weight antioxidants
"Oxidative stress" is an ill-defined term, being dependent on the method of its evaluation. Quantitation in terms of a universal criterion is impossible. The most commonly used biomarkers of OS are lipid peroxidation products, particularly hydroperoxides and aldehydes. In the MARK-AGE study of more than two thousand individuals, the OS, as evaluated on the basis of the steady state concentration of any given peroxidation product either does not correlate with the OS determined on the basis of another biomarker or, when the results based on two biomarkers correlate significantly with each other, the correlations were weak. We think that the different biomarkers are not merely different manifestations of one factor (OS). The results of our recent study accord with the hypothesis that different biomarkers reflect different, thus far unidentified, types of OS. The aim of our current research is to identify the difference between the alleged sub-groups (types) of OS.
Our working hypothesis is that the different biomarkers the reflecdifferent biomarkers different types of OS (i.e.) correlate differently with different antioxidants. We studied the correlations between the steady state concentrations of eight peroxidation products and 11 low molecular weight antioxidants. In fact, high concentration of MDA is associated with low GSH concentration, indicating that MDA and GSH reflect the same type of OS. By contrast protein carbonyls and nitro-tyrosine are markers of another type (or types) of OS. It appears that both the different biomarkers reflect different types of OS. We propose that the OS, as determined on the basis of the MDA or GSH reflect the same type of OS, which we denote OSa and the other biomarkers be denoted OSb.