甘肃甘草多糖的提取、纯化及其生物活性

以甘肃道地甘草为原料,采用响应面设计法优化超声波辅助热水法提取甘草粗多糖的工艺条件,粗多糖经DEAE-52阴离子交换柱和Sephadex G100凝胶柱纯化获得甘草多糖（GCP2）,利用气相色谱、高效液相色谱联用多角度激光散射技术（HPSEC-LLS）和红外光谱技术对GCP2的单糖组成、分子量分布和光谱特性进行了分析;并评价了GCP2的体外抗氧化性能和对6种供试细菌的抑制活性。结果表明,甘草多糖提取最佳工艺条件:温度为70℃、时间为85 min、液料比为13∶1、超声功率600 W,多糖平均提取得率为4.23%;GCP2是以α-糖苷键为主的还原性多糖,浅黄白色粉末,易溶于水;主要由阿拉伯糖、葡萄糖和半乳糖组成,摩尔比为0.166∶5.56∶1.60。HPSEC-LLS分析结果表明GCP2是由3种不同组分组成的聚合物构成,其中主要组分的重均分子量为1.378×105g/mol,红外光谱显示GCP2具有明显的多糖特征吸收峰,具有α-吡喃糖苷键。甘草多糖对羟自由基和超氧阴离子具有较好的清除能力,活性大小与多糖的浓度呈明显的线性关系,IC₅₀值分别为3.48 mg/m L和3.43 mg/m L,同时还具有一定的还原能力和抑菌作用。实验结果显示,GP2对6种细菌均具有较好的抑制作用,尤其是大肠杆菌和肺炎克雷伯菌。 

Extraction,purification and biological activity of polysaccharide from Glycyrrhiza uralcnsis in Gansu

Extraction, purification and biological activity of polysaccharide from Glycyrrhiza uralcnsis in Gansu were studied.The optimal ultrasonic-assisted extraction technology of polysaccharide was determined by response surface methodology. The polysaccharide of G. uralensis Fisch. ( GCP2) was obtained by the DEAE-52 anion exchange column chromatography and Sephadex G-100 gel filtration, respectively.The composition and molecular weight of the polysaccharide purified were analyzed by gas chromatography and high performance size exclusion chromatography with multi-angle laser light scattering ( HPSECLLS) .The antioxidant and antibacteria activities of GCP were determined in vitro. Results indicated that the optimal extraction conditions were as follows: extraction temperature 70 ℃, extraction time 85 min, liquid-solid ratio 13 ∶ 1, ultrasonic power600 W. Under the optimal extraction conditions, the extraction rate of polysaccharide was up to 4.23%.GCP2 was obtained by the chromatographic technique, which was a yellow white powder and reducing sugar without starch.GCP2 consists of arabinose, glucose and galactose with the molar ratio of 0.166∶ 5.56∶ 1.60, and had the characteristic of glycoconjugate by infrared spectrum analysis.HPSEC-LLS analysis results showed that the GCP2 was composed of three different components of polymer, average molecular weight of the main components was 1.378 × 10~5g/mol.GCP2 had strong scavenging effect on ·OH free radicals and O₂^-·free radicals with the IC₅₀ of 3.48 mg/m L and 3.43 mg/m L, and had the reductibility increased with the increase of concentration. Antibacteria test showed that GCP2 had better restraining effect on six different bacteria, especially for Escherichia coli and Pneumonia klebsiella strains.