Oxidative stress is inhibited by plant-based supplements: A quantitative lipidomic analysis of antioxidant activity and lipid compositional change

Dietary supplements containing plant extracts are often marketed as having antioxidant properties. Using complex lipid mixtures derived from cellular tissue, we perform a targeted lipidomic assessment of the antioxidant activity of five plant extract supplements. Formulations derived from grape seed, milk thistle, pine bark, turmeric and hawthorn extract were evaluated. Overall, we find evidence to suggest that all supplements suppressed in vitro lipid oxidation to some degree. Suppression of oxidation was most effective in the dominant lipid classes, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), which contain significant numbers of polyunsaturated lipids. Under the conditions of study, grape seed extract supplement was the most effective antioxidant showing statistically significant suppression of lipid oxidation in 11 of the 15 lipid classes quantified. Lipid compositional changes and metrics such as the PC: PE ratio and the double bond index were determined to provide an insight into the effect of oxidative stress and antioxidants on collective membrane properties. Finally, the likely stress that in vivo lipid oxidation could cause to cells, and the mitigating effects of supplements in this context, is also discussed.