Development of an Optional Preparation Method for Synthesis of Branched Fatty Acid Esters of Hydroxy Fatty Acids by Castor Oil

Branched fatty acid esters of hydroxy fatty acids (FAHFAs), a lipid class with physiological activities, have diverse structures and low natural abundance, necessitating efficient preparation methods. The study presented a method for large-scale 12-FAHFA preparation using 12-OAHSA (Oleic-acid-12-hydroxy stearic acid) as a template. The triglyceride of 12-OAHSA was first synthesized via esterification of fully hydrogenated castor oil with oleoyl chloride, purified by molecular distillation, and then subjected to enzymatic hydrolysis of 12-OAHSA with Lipozyme RM IM (Rhizomucor miehei, and enzyme activity: 360 IUN/g). Finally, 12-OAHSA was purified through a two-stage molecular distillation. Single-factor experiments optimized the parameters of esterification and hydrolysis. LC-MS/MS, NMR, and LC-MS3 were used to identify the synthesized 12-OAHSA. The yield of 12-OAHSA was 35.94%, and the purity was 82.59%. In this way, nine kinds of FAHFAs were synthesized, among which the branching positions of five FAHOAs need to be further confirmed. The method supports future pharmaceutical agent applications of FAHFAs.