P-3 - EPR study on radicals derived from sphingolipids and model compounds

Abstract

In our previous work, we studied the effect of ionization radiation on sphingolipids by analyzing the irradiation products and determining the kinetics of their formation. This enabled us to derive mechanisms for the free radical damage in sphingolipids, which may in the long run help to reach a better understanding of the origins of lipid damage related diseases. Here, we report now on the action of reactive oxygen species on sphingolipids and model compounds. The reactive oxygen species were generated by Ti3+-Fenton systems and radical formation was followed by cw X-band EPR using a mixing resonator. During fast flow at 12 ml/min, EPR signals of sphingosine, sphingomyelin, serinol and N-boc-serinol radicals in aqueous solutions were observed with well-resolved hyperfine structure. For sphingosine and sphingomyelin, the same spectrum of C-containing radicals was identified, regardless of whether the amino group was acylated or not. Interestingly, the EPR spectra of the model compounds changed significantly upon altering the pH-values of the solution, which is related to different reaction pathways leading to the formation of C- and N-centered radicals. In addition, the formation and decay kinetics of the model compounds at various pH values will be reported.