[Free radicals formed during UV-irradiation of unsaturated fatty acids containing peroxidation products]

On the irradiation of oxidized linolic acid an assymetric ESR signal with g-factor 2.0039 and the linewidth 30--33 Oe has been registered. The signal could be the result of photolysis of hydroperoxides. During prolonged irradiation of all the samples accumulation of alkyl radicals characterized by a symmetric signal with a well-defined ultrafine structure has been observed. An increase of the sample temperature up to 87 K in the presence of oxygen was preceded by transformation of alkyl radical R into RO2. All the radicals disappeared at the temperature of 160 K. All these processes seem to be the first phases of photoperoxidation of unsaturated fat acids in lipid-containing systems, including biological membranes.