Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 31, 2000
Publication Date: N/A
Interpretive Summary: One of the missions at the National Center for Agricultural Utilization Research (a research lab within the USDA) is to develop new uses for agricultural products such as wheat, corn, and soybeans. These new uses are intended to increase the value of agricultural products and, as a result, increase the value of the farmers' crops. Over the last year, a method has been developed to transform oils found in soybeans into substances that may potentially be used in sunscreens. The process involves a protein called a lipase, commonly found in bacteria, plants, and animals (including humans). This protein is used to combine a molecule found in plants, called a cinnamate, with oil found in soybeans. Several cinnamates absorb harmful UVA and UVB ultraviolet light given off by the sun and are the active ingredients in most sunscreens sold in the United States. The result of the process is a cinnamate-oil that may have the desired properties needed for use in waterproof sunscreens. If developed as a sunscreen ingredient, the cinnamate-oil would be made from all natural products, while providing a value added use for soybean oil. This would be beneficial to soybean producers as well as other scientists who may develop other applications based on the new lipase technology.
Technical Abstract: Commercially available lipases were screened for their ability to esterify ferulic acid (4-hydroxy-3-methoxy cinnamate). Novozym**R 435 was found to be the only lipase of those screened to convert ferulic acid to ethyl- and octyl ferulate, 20% and 14% yield respectively. The highest percent conversion was obtained using a 1:1 mole ratio of alcohol to ferulic acid in stirred batch reactions of anhydrous 2-methyl-2-propanol at 60 deg C using 1.0 equivalent (wt/wt based on ferulic acid) of Novozym**R 435. Increased water content and a higher alcohol:ethyl ferulate ratio had adverse effects on the lipase-catalyzed esterification. The Novozym**R 435 activity was tested in less polar solvents (anhydrous toluene and hexane) by monitoring the alcoholysis of ethyl ferulate with 1-octanol, which resulted in a 50% yield of octyl ferulate. The yield was improved to 83% by applying a 16 Torr vacuum for 5 min every 24 h to remove the ethanol byproduct. The optimal reaction parameters developed from the esterification and alcoholysis experiments were applied to the glycerolysis of ethyl ferulate with monoolein and triolein. The glycerolysis of ethyl ferulate with triolein in anhydrous toluene produced a combined, 44% yield of ferulyl monoolein and ferulyl diolein; a 20% greater yield than obtained when the glycerolysis was performed using monoolein. The greatest yield, 77%, of ferulyl monoolein and ferulyl diolein was achieved using a three-fold excess of neat triolein. The lipase-catalyzed glycerolysis of ethyl ferulate with triolein appears to be a technically feasible route to ferulyl-substituted-acylglycerols, which may possess potentially useful properties as sunscreen ingredients.