Study on the synthesis of dihydromyricetin linoleic acid ester
A two-step approach was employed to synthesize a liposoluble antioxidant dihydromyricetin lino-leic acid ester(DMYL)that can improve the lipid solubility and bioavailability of dihydromyricetin(DMY).To begin,linoleic acid was reacted with phosphorus trichloride to produce linolenic acid chlo-ride;Next,using ethyl acetate as the reaction system,DMY was esterified with linolenic chloride to pro-duce DMYL with different degrees of esterification(DS).After being purified with ethanol and petroleum ether,the synthesized product(DMYL)was scanned infrared.The results revealed that DMY had an absorption peak at 1 634.01 cm-1,which is the characteristic absorption peak of carbonyl groups,whereas DMYL had an absorption peak at 1 743.89 cm-1,which is the characteristic absorption peak of ketone.The data indicated that ester linkages had formed in DMYL.In the single factor experiments,the effects of sub-strate mass ratio,amount of catalyst phosphoric acid added,reaction temperature and reaction time on the esterification degree were studied.The best substrate mass ratio determined by single component experi-ments was 1∶3.The ideal addition amount of phosphoric acid was 40 μL/g.The optimal reaction tempera-ture was 45 ℃.The optimal reaction time was 8 hours.On the basis of single factor experiments,response surface methodology was utilized to investigate the effects of substrate mass ratio,amount of catalyst phos-phoric acid supplied,and reaction temperature on the DS.A multiple regression model equation was estab-lished,and optimized process conditions were obtained.The results showed that the substrate mass ratio(m/m)was 1∶3.2,and the amount of phosphoric acid added was 36 μL/g.The reaction temperature was 44 ℃,and under these conditions,the degree of esterification of DMYL could reach 3.01%±0.02%.In summary,the model can predict the preparation process of dihydromyricetin linoleic acid ester well,and provide theoretical basis for the full development and utilization of dihydromyricetin.