槲皮素-羧甲基甘薯淀粉酯的合成

Synthesis of Quercetin-Carboxymethyl Sweet Potato Starch Ester

以甘薯淀粉为原料,依次经过羧甲基化、槲皮素共价修饰两步改性,得到槲皮素-羧甲基甘薯淀粉酯,并采用单因素及响应面试验考察制备工艺条件对产物取代度的影响。单因素试验结果表明,其取代度随反应底物配比(N_(槲皮素/AGU))(X_1)的增加而增加,随活化试剂与羧甲基甘薯淀粉脱水葡萄糖基的物质的量比(N_(EDC/AGU))(X_2)及反应体系pH值(X_3)的增加呈先增加后降低的趋势;响应面试验结果表明,N_(EDC/AGU)及反应体系pH值对取代度有极显著影响(P<0.01),而N_(槲皮素/AGU)以及二次项和交互项对取代度的影响不显著(P>0.05)。得到最佳工艺条件为羧甲基甘薯淀粉质量浓度51 g/L、N_(槲皮素/AGU) 2∶1,N_(EDC/AGU) 1.8∶1、反应体系pH 7.4,可制得最大取代度(0.114 9)的槲皮素-羧甲基甘薯淀粉酯。通过检测槲皮素从产物的水解释放确认产物的合成。

Quercetin-carboxymethyl sweet potato starch ester was synthesized by covalent attachment of quercetin to carboxymethyl sweet potato starch. The influence of preparation conditions on the degree of substitution (DS) was investigated by the combined use of one-factor-at-a-time (OFAT) method and response surface methodology (RSM). The OFAT results indicated that the DS increased with increasing molar ratio of quercetin to anhydroglucose unit (AGU) of sweet potato starch (Nquercetin/AGU), while it increased then decreased with increasing molar ratio of activating agent to AGU (NEDC/AGU) and reaction pH. Furthermore, the RSM results revealed that both NEDC/AGU and reaction pH had a significant effect on the DS(P < 0.01), while Nquercetin/AGU as well as the quadratic and interactive terms showed no significant effect on the DS (P > 0.05). Finally, the optimal reaction conditions were obtained as follows: carboxymethyl sweet potato starch concentration 51 g/L, Nquercetin/AGU 2:1, NEDC/AGU 1.8:1 and initial pH 7.4. The maximum DS value of 0.114 9 was obtained under the optimized conditions. The covalent linkage of quercetin to carboxymethyl sweet potato starch was confirmed by detectable quercetin release from the product after hydrolysis.