Initiation Reactions of Lipid Peroxidation: A Raman Spectroscopic and Quantum-Mechanical Study

Abstract

Near-infrared (NIR) Raman spectroscopy has been used to observe the spectrum changes of linolenic acid during the iron-dependent lipid peroxidation reactions. The intensity of several bands including those at 726, 977, 1264, 1658, and 3014 cm⁻¹ decreased after lipid peroxidation. Other notable changes after lipid peroxidation include the appearance of a couple of new bands at 1165 and 1638 cm⁻¹. The Raman spectrum change was suppressed by an antioxidant, 21-aminosteroid. Harmonic ab initio vibrational analysis was performed for two model structures: one for the pure linolenic acid and another for a peroxidation product. The calculations by the Hartree–Fock (HF) method and a density functional theory (DFT) indicate that a new band which appeared at 1638 cm⁻¹ after lipid peroxidation is due to the rearrangement of skeletal double bonds.