Generation of alpha-hydroxyaldehydic compounds in the course of lipid peroxidation

Based on 18O-labeling experiments a general scheme for the generation of hydroxy aldehydic compounds in the course of lipid peroxidation of linoleic acid is developed. Key intermediates are obviously dioxygenated fatty acids, since after reduction with either NaBH4 or Rh/H2 1.2 and 1.6 dihydroxy fatty acids can be identified. The postulated mechanism not only explains the formation of 2-hydroxyalkanals but also supports earlier hypothesis concerning the generation of 4-hydroxyalkenals. In addition it predicted the occurrence of (n - 1)-hydroxy-n-oxo fatty acids as additional oxidation products. A search for these previously unknown autoxidation products of linoleic acid was indeed successful.