Lipase-catalyzed synthesis of phytostanyl esters in non-aqueous media

Stanols are more effective and safer than sterols in lowering plasma total cholesterol, while stanol esters are advantageous since this compound has a better solubility than the free stanols, which contribute to the practical application in foods. The current work focuses on the synthesis of phytostanyl esters from plant stanols and fatty acid such as lauric acid, including screening of various source lipases and selecting solvents of different Log P values. Among lipases from different origins, the immobilized Novozym 435 lipase from microorganism was found to be the best biocatalyst, while plant lipase from Carica papaya and animal lipase from Porcine pancreas are quite ineffective as biocatalyst for the esterification of plant stanols with fatty acid. The highest phytostanyl laurate esterification degree of 79.3% was obtained under the selected conditions: 25 μmol/mL plant stanols, 100 μmol/mL lauric acid, 80 mg/mL 3 Å molecular sieves and 40 mg/mL Novozym 435 at 150 rpm and 55 °C for 96 h in 10 mL of n-hexane. The chemical structure of sitostanyl laurate was confirmed by FT-IR, MS and NMR. The comparison of solubility of plant stanols and phytostanyl laurate in plant oil was done.

Figure optionsDownload as PowerPoint slideResearch highlightsThis paper described a method for lipase-catalyzed synthesis of phytostanol esters in non-aqueous media. Two aspects of this manuscript will make it interesting to general readers of enzymatic synthesis of phytostanyl fatty acid esters. First, phytostanyl esters of long chain fatty acids were synthesized for the first time, and identification of the produced sitostanyl laurate was conducted by TLC, FT-IR, MS, and NMR. Second, lipases from different origins were screened for the synthesis of phytostanyl esters. Among lipases from different sources, the immobilized Novozym 435 lipase from microorganism was found to be the best biocatalyst, while plant lipase from Carica papaya and animal lipase from Porcine pancreas are quite ineffective as biocatalyst for the esterification of plant stanols with fatty acid. The present report also optimized reaction parameters and the highest phytostanyl laurate conversion of 79.3% was obtained under the selected conditions. Thus, the results can provide the evidence of phytostanyl esters efficiently formed in the presence of enzyme.