Antioxidative effects of alkyl esters of sinapic acid on flaxseed oil and its fatty acid methyl esters

Alkyl esters of sinapic acid were enzymatically synthesized by using hexanol CH3(CH2)5OH and palmitoyl chloride CH3(CH2)14COCl as acyl donors. The lipid oxidation retarding activities of these conjugates were determined using different methods in two lipid media; bulk flaxseed oil and its fatty acid methyl esters (FAME). Palmitoyl sinapate more efficiently slowed down the formation of primary and secondary oxidation products in both lipid media. In terms of DPPH radical scavenging activity, beta-carotene bleaching and TEAC assays, it provided higher activity compared to hexyl ester in FAME. Hexyl ester was more active in bulk oil in terms of antioxidant activity analyses. The alkyl side chain length of these molecules had an impact on their antioxidative activity and this effect differed according to the environment in which they were used. The conjugates remained more stable on storage compared to the phenolic compounds originally found in the oil samples. image