Detection of 2,6-cyclolycopene-1,5-diol in breast nipple aspirate fluids and plasma: a potential marker of oxidative stress.

An high-performance liquid chromatography method with electrochemical detection was developed to quantify both 2,6-cyclolycopene-1,5-diol and lycopene in plasma and breast nipple aspirate fluids (NAF). As an example of the utility of this assay, levels in plasma and NAF of 11 women were examined and compared with levels of 8-isoprostane, a commonly used marker of lipid oxidation. Levels of 2,6-cyclolycopene-1,5-diol and 8-isoprostane were higher in NAF than in plasma, but levels of lycopene were lower in NAF than in plasma. Levels of 2,6-cyclolycopene-1,5-diol in plasma and in NAF were significantly correlated with both lycopene and 8-isoprostane levels. This is consistent with the dependence of 2,6-cyclolycopene-1,5-diol levels on both dietary intakes of lycopene and oxidative stress levels. For the correlations between NAF and plasma, lycopene levels were significantly correlated, whereas 2,6-cyclolycopene-1,5-diol levels were not, indicating that levels of 2,6-cyclolycopene-1,5-diol in NAF are difficult to predict from plasma levels. The high levels of 2,6-cyclolycopene-1,5-diol and 8-isoprostane in NAF are consistent with high levels of oxidative stress in the breast.