Palmitoylspermine: A potent antioxidant in bulk oil and emulsion

This study explores the potential of polyamines and their acylated derivatives as antioxidants in plant oils and emulsions. We have shown that linseed, rapeseed, sunflower, and soybean oils naturally contain spermidine and spermine (SPM). These polyamines added to methyl linolenate effectively prevent lipid oxidation in the absence of other antioxidants. However, they showed no activity in in vitro antioxidant assays (DPPH, ABTS, Folin-Ciocalteu) and did not express Fe²⁺ binding. Butanoylspermine and palmitoylspermine (SPM-C16) were synthesised and their antioxidant activity was compared to underivatised polyamines and some commonly used antioxidants. SPM and SPM-C16 demonstrated the highest antioxidant activity in bulk oils, preventing hydroperoxide formation and stabilising polyunsaturated fatty acids. No prooxidative effects were observed in the 0.1 to 0.8 mmol/kg concentration range. However, in oil-in-water emulsions, only SPM-C16 retained its efficacy. These findings highlight the considerable potential of polyamines and their derivatives for stabilising various lipid systems.