Acilação enzimática de naringina com o ácido 12-hidróxi-9-Z-octadecenóico, catalisada por lipase B de Candida antarctica

Abstract

Flavonoid glycosides are very important compounds among natural products. They show several biological activities, mainly scavenger. They are characterized by a low solubility and stability in lipophilic media. So its use has been difficult in pharmaceutic, cosmetic and food preparation. In order to take advantage of these properties, the enzymatic acylation of these molecules employing fatty acids and immobilized lipase B from Candida antarctica has been suggested as a interesting route because don’t affect the biological activities. The aim of this work was to compare the performance of the esterification and transesterification reactions during the enzymatic acylation of naringin with ricinoleic acid and castor oil, respectively. The ricinoleic acid (12-hydroxy-9-Z-octadecenoic acid) is an hidroxy-unsaturated fatty acid that naturally occurs in castor oil. The enzymatic synthesis of flavonoid ester was carried out in shaker heating at 50◦C under agitation during 120 hours using dry acetone. The reactions were monitored quantitatively by HPLC-DAD. The naringin ester was purified by liquid–liquid extraction followed by column chromatography. The obtained results indicated that the transesterification reactions obtained higher conversion yields (33%) compared to esterification (24%). These reactions also carried out so compare heating source differents such as conventional and with microwave energy. All data were statistically analyzed by ANAVA and Tukey’s test with 5% level of significance. The NMR analyses show the esterification which takes place on the primary OH of glucose moiety of naringin in C-6″ position. The feasibility of the enzymatic acylation of naringin with an hydroxyl-unsaturated fatty acid from castor oil was clearly demonstrated in this work.