Antioxidant activity of phytosteryl phenolates

Abstract

Phytosteryl phenolates occur naturally in many cereals and were successfully synthesized through a two‐step chemoenzymatic process, as previously reported. They were also found to exhibit a system dependent antioxidant activity. Three model systems were employed in this study to shed light on the antioxidant activity and action mechanisms involved. The maintaining or enhancing of the antiradical capacity of phytosteryl phenolates in the DPPH assay suggested that these derivatives might be used as antioxidants in more lipophilic systems. However, reducing power of phytosteryl phenolates was lower than that of their phenolic acid counterparts, possibly due to their poor solubility in the aqueous test medium or via micelle formation. In the DNA scission test, phytosteryl phenolates showed either the same/or lower DNA retention ability against both peroxyl and hydroxyl radicals with the exception of phytosteryl caffeates and sinapates, which showed enhanced DNA retention ability against hydroxyl radical. Phytosteryl caffeates also displayed higher activity in DNA retention against peroxyl radical. The antioxidant activity of phytosteryl phenolates was similar or superior to that of their parent phenolic acid counterparts, suggesting their potential use as phenolic acid alternatives with added benefits of phytosterols in the food industry.DPPH radical scavenging ability of phenolic acids and their derivatives. CA, caffeic acid; FA, ferulic acid; SA, sinapic acid; and VA, vanillic acid.