Production of cinnamoyl lipids using immobilized Proteus vulgaris K80 lipase and an evaluation of their antioxidant activity

• Two cinnamoyl lipids, CMOG and CDOG, were synthesized by immobilized K80 lipase-mediated interesterification reaction.
• Reaction conditions including organic solvent system, substrate concentration, and molar ratio of substrates were optimized.
• CMOG and CDOG have strong radical scavenging activities towards DPPH and ABTS radicals in non-polar solvents.

Natural phenolic acids, such as cinnamic acid, have antioxidant and other biological activities. However, their hydrophilic groups reduce antioxidant efficiency in fat and oil systems. To overcome this restriction in their usage, natural phenolic acids have been modified via an enzymatic transesterification reaction. The lipase-catalyzed transesterification reaction has received attention due to advantages, such as stereo and regioselectivity and substrate specificity. In this study, ethyl cinnmate (40 mM) and triolein (240 mM) were used as substrates and immobilized Proteus vulgaris K80 lipase (1 U) was used as enzyme catalyst. When the interesterification reaction was performed in 5 mL n-hexane/toluene (85:15, v/v) at 35 °C for 72 h, cinnamoyl monooleyl glycerol (CMOG) and cinnamoyl dioleyl glycerol (CDOG) were produced and the conversion yield was 70%. These cinnamoylated lipid products were collected by preparative liquid chromatography and identified using high resonance mass spectrometry. CMOG and CDOG showed radical scavenging activities of 45% and 69%, respectively, in n-hexane system using DPPH assay and 56% and 20%, respectively, in dichloromethane/DMSO (8:2, v/v) system using ABTS assay.

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