Antioxidant properties of feruloyl glycerol derivatives

The natural plant components, 1-feruloyl-sn-glycerol (FG) and 1,3-diferuloyl-sn-glycerol (F₂G), were synthesized by the enzymatic esterification of glycerol and soybean oil mono- and diacylglycerols, respectively, with ethyl ferulate. The isolated FG and F₂G were examined for their antioxidant activities as free radical scavengers (DPPH assay) and peroxyl lipid oxidation inhibitors (TBARS assay). The H atom transfer kinetics, as monitored by DPPH free radical bleaching, of FG showed that the mono-feruloyl glycerol acted as a rapid antioxidant (50% reduction of DPPH radical < 5 min) in ethanol solutions while F₂G and ferulic acid activity rates were in the range of intermediate antioxidants (50% reduction of DPPH radical in 5-30 min). FG and F₂G showed similar activity as the control agent, ethyl ferulate, towards the inhibition of the AAPH-induced peroxyl radical oxidation of surfactant emulsified γ-linolenic acid. A slight excess of feruloyl groups was sufficient to completely suppress the formation of secondary lipid oxidation products.