Comparison of the Radiosensitivity of Unsaturated Fatty Acids, Structured as Micelles or Liposomes, under Different Experimental Conditions

Summary

A comparison has been made between the peroxidation rate as a result of ionizing radiation in liposomes prepared from phospholipids which were extracted from biological membranes, in single component micelles and in micelles of mixed composition. The ease of fatty acid oxidation in the different preparations was studied at a variety of pH values. The damage has been quantified spectro-photometrically in terms of diene conjugation (233 nm) and as the disappearance of fatty acids by gas chromatography. The ease of fatty acid oxidation was in the following order for the liposomal and mixed micelle preparations: 22:6 > 20:4 > 18:3 > 18:2. For single component micelles the order was reversed: 18:2 > 18:3 > 20:4 > 22:6. The micellar lipid preparations were pH-dependent in their response to radiation, which was demonstrated by a dip in the pH-response curve. Peroxidation of especially 22:6 was promoted when present in mixed micelles with 18:2.