Abstract
Purpose: :
The aim of this study was to compare 8-hydroxy-2’-deoxyguanosine (8-oxo-dG) levels in serum (a biomarker of oxidative stress) of subjects with high and low serum concentrations of lutein (L).
Methods: :
112 serum samples were selected from a pooled database of normal subjects (n = 485). Subjects with the lowest (n = 56, lowest quartile, Group 1) and highest (n = 56, highest quartile, Group 2) serum concentrations of L (assessed by HPLC) in this database were selected for analysis. We measured a biomarker of oxidative damage in serum using an enzyme-linked immunosorbent assay (ELISA), which measures levels of 8-oxo-dG in serum.
Results: :
Mean (± SD) serum concentrations of L were significantly lower in Group 1 when compared to Group 2 (mean [± SD] serum L µmol/L: 0.198 ± 0.036 and 0.883 ± 0.214, respectively, p < 0.01). We report that Group 2 subjects have, on average, significantly higher mean (± SD) 8-oxo-dG levels when compared to Group 1 subjects (8-oxo-dG levels ng/mL: 54.68 ± 18.66 and 40.79 ± 19.59, respectively, p < 0.01).
Conclusions: :
The serums with higher serum L concentrations demonstrated higher levels of 8-oxo-dG, indicating (unexpected) higher levels of oxidative stress in these subjects. However, given the known antioxidant properties of L, we suggest that the 8-oxo-dG assay is actually measuring DNA repair (and not oxidative stress), as 8-oxo-dG is released during DNA repair. It is likely that DNA repair enzymes are susceptible to reactive oxygen species and that higher amounts of serum L reduces these species, which gives rise to higher rates of repair. It is also possible that the higher levels of 8-oxo-dG found in the serum represent lower DNA levels of 8-oxo-dG, resulting from the potential antioxidant effect of L.
Keywords: macular pigment • oxidation/oxidative or free radical damage