The antioxidative effect of dehydroepiandrosterone-sulfate (DHEA-S) in vitro and in vivo – chemiluminometric determination of hydroperoxygroups in lipoproteins

In order to clarify the mechanism of antiatherogenic action of several steroids, we investigated the effects of DHEA-S on the photodioxygenation of human lipoproteins (LDL, HDL). First we found that up to 30% of circulating DHEA-S in humans is located in lipoproteins which were separated by ultracentrifugation. We’ve developed a new chemiluminometric detection method of hydroperoxy-groups in lipoproteins. The separated lipid particles were incubated with several amounts of DHEA-S (5–50µmol/l) and treated for 30min with UV-light in presence of rose bengale and oxygen. The generated reactive singlet oxygen leads in a nonradical pathway to the formation of HOO-groups as primarily lipid peroxidation state. The chemiluminometric measuring signal was directly proportional to the concentration of HOO-groups in the HDL and LDL fractions. We found a drastically decrease of lipid peroxidation state of both HDL and LDL in comparison to not DHEA-S incubated samples. In cases of patients with aortic surgery we found a significant decrease of plasma DHEA-S and increase of androstendione. This effect could be verified by in vitro experiments. It was shown that one of the reaction products of the antioxidative pathway of DHEA-S is androstendione. In conclusion, the protective role of DHEA-S may be caused by inhibition of lipid peroxidation via the singlet oxygen nonradical pathway in vivo.