不同取代度羧甲基化罗汉果多糖的制备及生理活性研究

刘贵珍; 杨志伟

doi:10.13386/j.issn1002-0306.2022090194

不同取代度羧甲基化罗汉果多糖的制备及生理活性研究

Preparation and Physiological Activity of Carboxymethylated Siraitia grosvenorii Polysaccharide with Different Degrees of Substitution

摘要

摘要: 为探讨不同羧甲基化取代度对罗汉果多糖（Siraitia grosvenorii polysaccharide，SGP）生理活性的影响，以SGP为原料，采用溶媒法制备羧甲基化罗汉果多糖（carboxymethylated Siraitia grosvenorii polysaccharide，CSGP）。分析氯乙酸浓度、反应时间、氢氧化钠浓度对取代度的影响，制备得到取代度为0.28~1.09的CSGP。对不同取代度的CSGP进行理化性质表征，并采用体外生理活性实验探讨不同取代度对降血糖活性和抗氧化活性的影响。结果表明：高效凝胶渗透色谱结果显示经过修饰的CSGP分子质量小于SGP；红外图谱在1317 cm⁻¹处出现新的吸收峰，表明羧甲基成功引入多糖中；扫描电镜结果表明随着取代度的增加，CSGP微观表面形态变得更加破碎并出现卷曲化现象；刚果红实验显示高取代度的CSGP-H三股螺旋结构消失。体外生理活性实验表明：在质量浓度为6 mg/mL时具有中等取代度的CSGP-M对α-淀粉酶的抑制率、DPPH自由基、羟基自由基的清除率最高分别达到44.36%±1.30%、63.17%±2.07%、70.21%±1.89%，相较于SGP、CSGP-L、CSGP-H具有更好的降血糖活性和体外抗氧化活性。随着取代度的增加，CSGP-H对α-淀粉酶的抑制率、DPPH自由基、羟基自由基的清除率分别降到11.65%±0.26%、47.45%±0.79%、34.85%±0.78%。论文研究结果表明具有中等取代度的CSGP才可以发挥最佳的生理活性。

Abstract: To investigate the effect of carboxymethylated with different degrees of substitution on the properties of Siraitia grosvenorii polysaccharide (SGP), carboxymethylated Siraitia grosvenorii polysaccharide (CSGP) was prepared by solvent method by using the raw material of SGP. The effects of chloroacetic acid concentration, reaction time, and sodium hydroxide concentration on the degree of substitution were analyzed, and the CSGP with the degree of substitution ranging from 0.28 to 1.09 was prepared. The physicochemical properties of CSGP with different substitution degrees were characterized, and the effects of substitution degrees on hypoglycemic activity and antioxidant activity were investigated by in vitro physiological activity experiments. The high-performance gel permeation chromatography revealed that the molecular mass of CSGP was smaller than that of SGP. The results of FTIR manifested a new absorption peak at 1317 cm⁻¹, indicating that carboxymethyl was successfully introduced into the polysaccharide. The results of scanning electron microscopy showed that with the increase of substitution degree, the surface morphology of CSGP became more fragmented and appeared to curl. Congo red experiment revealed that the triple helix structure of CSGP with high substitution degree disappeared. In vitro physiological activity experiment showed that 6 mg/mL of the CSGP-M had the highest α-amylase inhibition, DPPH, and hydroxyl radical scavenging rates of 44.36%±1.30%, 63.17%±2.07%, and 70.21%±1.89%, respectively. Compared with SGP, CSGP-L and CSGP-H, CSGP-M with medium degree of substitution has the best hypoglycemic activity and antioxidant activity in vitro. When the degree of substitution was increased to 1.09, the inhibition rate of α-amylase, DPPH and hydroxyl radical scavenging rate of CSGP-H decreased to 11.65%±0.26%, 47.45%±0.79%, and 34.85%±0.78%, respectively. The results indicated that CSGP with medium degree of substitution could exert the best physiological activity.