Antioxidant activity of phytosteryl phenolates in different model systems

As part of a comprehensive study of the physiochemical and biological properties of phytosteryl phenolates, successfully synthesized chemoenzymatically in our lab, their antioxidant activity was evaluated using three different in vitro model systems, namely bulk oil model system, β-carotene–linoleate model system and low-density lipoprotein cholesterol (LDL-C) oxidation assay. In the bulk oil system, phytosteryl phenolates showed similar or lower antioxidant activity compared with those of phenolic acids. However, in β-carotene–linoleate assay, an emulsion model system, phytosteryl phenolates showed enhanced antioxidant activity except phytosteryl ferulates. Moderate inhibitory effect of LDL-C oxidation by phytosteryl phenolates was observed. These findings demonstrate that use of multidimensional antioxidant activity determinations with differing reaction mechanisms is necessary to provide an overall understanding of the mechanisms of antioxidant action of phytosteryl phenolates.