Oxidation of lipids and membranes II: Effects of oxidants on cerebral white matter homogenates

Abstract

Bovine cerebral white matter homogenates were oxidized by various oxidizing solutions of equal molarity and subsequently extracted with water. Most of the oxidants tested (K-dichromate, FeCL3, H2O2, O2, and chloroperbenzoic, ascorbic, performic, and periodic acids) rendered the various myelin constituents less extractable than the constituents of unoxidized control homogenates. KMnO4, and to a lesser degree hemoglobin, rendered myelin constituents more extractable with water than those of the control homogenates. The findings indicate that most of the oxidants produced stabilization of the lamellar pattern, probably through cross-linking and polymerization. KMnO4 and hemoglobin caused labilization and breakdown of the membranous structure. Proof that stabilization of membranes is caused by some oxidants and that fragmentation occurs by the action of KMnO4 and hemoglobin was obtained by the light scattering technique and by electron microscopy of the oxidized homogenates. Evidence obtained indicated that formation of hydrophobic end groups during oxidation favors polymerization, while prevalence of hydrophilic groups is associated with fragmentation.