Evaluation of antioxidant and antimicrobial activity of phenolic lipids produced by the transesterification of 4-hydroxyphenylacetic acid and triglycerides

Several phenolic compounds derived from plant biomass are attracting attention because they display high antioxidant activity. In this study, antioxidant activity was confirmed in 4-hydroxyphenylacetic acid (HPA), and transesterification reaction using Candida antarctica lipase B was performed to enhance the solubility of HPA. The HPA-diolein (HPA-DON) was synthesized from HPA and triolein, while the HPA-fish oil diglyceride (HPA-dFO) was synthesized from HPA and Menhaden fish oil. To increase the conversion yield, the enzyme reaction conditions of the substrate molar ratio, enzyme amount, and reaction time were optimized. After the reaction, HPA-DON and HPA-dFO were purely separated, using prep-LC. The activity assays using DPPH and ABTS radicals confirmed that HPA-DON and HPA-dFO have antioxidant activity. HPA-DON has high activity in non-polar solvents, while HPA-dFO has strong activity in both polar solvents and non-polar solvents. In addition, HPA-dFO has the growth inhibition activity for Bacillus coagulans, Geobacillus stearothermophilus, and Alcaligenes faecalis that cause food spoilage. Therefore, HPA-dFO is a new synthetic substance that has both antioxidant activity and antibacterial activity. The results indicate that these HPA-derivatives can be expected to be developed as important materials in the food and cosmetics industries.