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Synthesis of novel octyl sinapate to enhance antioxidant capacity of rapeseed–linseed oil mixture

Szydłowska‐Czerniak, Aleksandra, Rabiej, Dobrochna, Krzemiński, Marek
Journal of the science of food and agriculture 2018 v.98 no.4 pp. 1625-1631
2,2-diphenyl-1-picrylhydrazyl, antioxidant activity, antioxidants, chromatography, coumaric acids, esterification, esters, hydrophilicity, inhibitory concentration 50, spectral analysis, vegetable oil
BACKGROUND: Lipophilisation allows the formation of new functionalised antioxidants having beneficial properties compared to natural hydrophilic phenolic acids. Therefore, this work focused on the synthesis of lipophilic antioxidants, such as a new octyl sinapate, octyl caffeate and octyl ferulate using the modified Fischer esterification of selected hydroxycinnamic acids with 1‐octanol. RESULTS: The lipophilic octyl sinapate was obtained for the first time with satisfactory yield (83%) after purification by column chromatography. The identity of the synthesised phenolipids was confirmed by chromatographic and spectroscopic analyses. Antioxidant capacity of phenolipids was determined by DPPH (IC₅₀ = 35.87–52.24 μg mL⁻¹) and ABTS (IC₅₀ = 39.45–48.72 μg mL⁻¹) methods and compared with IC₅₀ values (7.37–35.30 μg mL⁻¹ and 7.55–41.67 μg mL⁻¹, respectively) for well known antioxidants. The antioxidant capacity of rapeseed–linseed oil enriched with the purified esters was about two to 30 times higher in comparison with a non‐supplemented oil. CONCLUSION: The novel octyl sinapate as well as octyl caffeate and octyl ferulate have antioxidant properties and lipophilic character, therefore they may be added to vegetable oils as potential antioxidants for tackling oxidative processes. © 2017 Society of Chemical Industry