超声场中L-抗坏血酸亚油酸酯的酶法合成及其抗氧化性研究

Ultrasound assisted enzymatic synthesis and antioxidant activity of L-ascorbyl linoleate

以L-抗坏血酸和人体必需不饱和脂肪酸亚油酸为原料,通过超声-酶法协同法合成L-抗坏血酸亚油酸酯,并通过条件优化确定了最佳合成条件:L-抗坏血酸10 mmol,亚油酸30 mmol,4分子筛5 g,叔戊醇50 m L,固定化脂肪酶(Novozym435)0.44 g,反应温度55℃,反应时间6 h,产率为35%。采用红外光谱、质谱及核磁共振碳谱对最终产物进行结构鉴定,确定终产物为L-抗坏血酸亚油酸酯。并对比了L-抗坏血酸亚油酸酯与抗氧化剂L-抗坏血酸、L-抗坏血酸棕榈酸酯和维生素E的抗氧化能力,结果表明,4者的清除羟基自由基、DPPH自由基的能力及还原能力大小为L-抗坏血酸>L-抗坏血酸棕榈酸酯>L-抗坏血酸亚油酸酯>维生素E,油脂抗氧化能力强弱为L-抗坏血酸棕榈酸酯>L-抗坏血酸亚油酸酯>维生素E>L-抗坏血酸。

The synthesis of L-ascorbyl linoleate catalyzed by Novozym（R） 435 under ultrasonic irradiation was in- vestigated. The synthesis conditions were optimized as fellows： l0 mmol L-ascorbic acid, 30 mmol linoleic acid, 440 mg lipase, 5 g molecular sieves, 50 mL 2-methyl-2-butanol, reaction temperature 55℃ and reaction time 6 h. Under this condition, the product yield reached 35%. Structural identification and characterization were confirmed by IR, ESI-MS and IaC-NMR and the antioxidant activities were evaluated when compared with those of L-ascorbic acid, L- ascorbyl palmitate and vitamin E. The results showed that the order of their hydroxyl and DPPH radicals scavenging activities and reducing power from high to low was as follows ： L-ascorbic acid 〉 L-ascorbyl palmitate 〉 L-ascorbyl lino- leate 〉 vitamin E. The order of induction time from long to short was as follows： L-ascorbyl palmitate 〉 L-aseorbyl li- noleate 〉 vitamin E 〉 L-ascorbic acid.