It has been reported that 2-monoolein exhibits various biological activities. In this study, an enzymatic method is reported for the synthesis of highly pure 2-monoolein by ethanolysis of oleic acid-rich oil. The effects of solvent type, addition amounts of solvent and lipase, and reaction time on 2-MAGs content in the crude reaction mixture were investigated. Under the optimized conditions, there was 37.6% (area/area) 2-MAGs produced in the crude mixture. 2-MAGs were obtained at 97–98% purity and 33.6% yield (w/w) after fractionation in 85% ethanol aqueous solution and hexane to fully remove impurities including DAGs, TAGs, and fatty acid ethyl esters. Subsequently, 2-MAGs were purified further by two-step crystallization in hexane to remove saturated and polyunsaturated 2-MAGs to obtain pure 2-monoolein. After the two-step crystallization, 97.5% 2-monoolein was obtained at 78.3% yield (w/w). Compared to previous methods, our method for the synthesis of 2-monoolein is easier to scale up, obtain highly pure 2-monoolein product and more economical. In addition, the study on the effect of solvent type suggests that selectivity of the lipase and acyl migration of 2-MAGs may be affected by reaction solvent polarity.
Practical application: Synthetic 2-monoolein can be used as emulsifier and surfactant in food, pharmaceutical and cosmetic and other industries. In addition, 2-monoolein has exhibited strong antioxidation and anti-atherosclerotic properties in vitro and in a cellular model. Thus, 2-monoolein has potential application in treating cardiovascular diseases.