Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 16, 2000
Publication Date: N/A
Interpretive Summary: One of the missions at the National Center for Agricultural Utilization Research is to develop new uses for agricultural products such as wheat, corn and soybeans. We have previously reported a method of using an enzyme to transform plant oils into substances that may potentially be useful as an "all natural" sunscreen. We have recently improved on this method by halving the time needed for the reaction to reach completion while maintaining the same yield of sunscreen material obtained. The new process involves conducting the enzymatic transformation of the plant oils in carbon dioxide under elevated pressure and temperature (3500 psi, 80 deg C). Carbon dioxide offers benefits over other organic solvents because it is nontoxic and environmentally safe.
Technical Abstract: Novozym**R 435 catalyzed transesterification of ethyl 4-hydroxy-3-methoxy cinnamate, ethyl ferulate (EF), with triolein to form the ultraviolet (UV) absorbing lipids, ferulyl mono- and diolein (FMO and FDO), has been conducted using supercritical CO2 (SC-CO2) batch reactions. The alcoholysis of 0.1 M EF with 0.1 M 1-octanol in SC-CO2 to form octyl ferulate (OF) was used as a model reaction to optimize pressure and temperature conditions. Conditions ranging from 45 to 80 deg C and 1,500 to 5,000 psi were tested with a maximum conversion of 53% of the EF being achieved at 2000 psi and 80 deg C after 24 h. These optimized conditions applied to the transesterification of EF with triolein effected a combined FMO and FDO yield of 69%. Triolein exhibits higher solubilities in SC-CO2 at higher pressures; therefore, the transesterification was performed at 80 deg C over a range of pressures from 2000 - 5000 psi. Results showed that a maximum yield of 74% of FMO and FDO was reached at 80 deg C and 3,500 psi (48 h). Compared to the FMO and FDO synthesis conducted neat or in toluene, the synthesis of the UV-absorbing lipids in SC-CO2 affords higher yields within a shorter amount of time. Therefore, the transesterification of EF with triolein in a SC-CO2 batch reaction is a viable route to UV-absorbing lipids that could be used as active ingredients in sunscreen formulations.