Regular articleEnzymatic preparation of novel caffeoyl structured lipids using monoacylglycerols as caffeoyl acceptor and transesterification mechanism

•Novel derivatives CSLs of caffeic acid were successfully synthesized.•Different MAGs as caffeoyl acceptors on reaction selectivity were compared.•Thermodynamic, kinetic analyses and reaction mechanism were established.•High EC conversion and CSLs yield were obtained under the optimized conditions.

Caffeoyl structured lipids (CSLs), including hydrophilic glyceryl caffeates (GCs) and lipophilic caffeoylated acylglycerols (CAGs), are novel derivatives of caffeic acid. In the work, CSLs were successfully synthesized by enzymatic transesterification using different monoacylglycerols as caffeoyl acceptors. The effect of monoacylglycerols on reaction selectivities (for hydrophilic GCs and lipophilic CAGs) was compared. The thermodynamics, kinetic analyses, and reaction mechanism of the transesterification were also evaluated. The apparent activation energies for the transesterification, GCs and CAGs formation were 23.10, 12.03, 28.32 kJ/mol for monooleate, and 25.85, 19.19, 32.02 kJ/mol for monostearate, respectively. The values of Vmax, Km' and KIA for the reaction using monooleate as caffeoyl acceptors were 1.19 × 10−3 mol/(L min), 0.82 mol/L, and 2.31 mol/L, respectively. High ethyl caffeate conversion and CSLs yields (98.2 ± 1.8%, 94.7 ± 2.8% for monooleate; and 96.8 ± 2.3%, 93.9 ± 2.7% for monostearate) were achieved under the optimized conditions.

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