夏秋季‘石佛翠’茶树鲜叶多糖提取、分离纯化与抗氧化活性研究

Extraction,Separation,Purification,and Antioxidant Activity of Polysaccharides in Summer and Autumn Shifocui Tea

【目的】探究优化‘石佛翠’茶树鲜叶多糖的提取工艺,并对获得的纯化多糖组分进行理化性质和体外抗氧化活性测定,为其在功能食品中的开发利用提供一定参考,并为夏秋茶资源多样化开发提供途径。【方法】以石佛翠多糖(CSTP)提取率为评价指标,采用单因素实验结合响应面法探究水提法提取石佛翠多糖的最佳条件;通过琼脂糖凝胶CL-4B柱层析得到纯化多糖组分CSTP-1、CSTP-2,采用苯酚硫酸法与间羟基联苯法检测其糖含量,高效液相色谱(HPLC)法测定其分子量,并进行红外光谱扫描;以DPPH·、·OH、O^(2-)·清除率为指标,探究2个纯化多糖组分的抗氧化活性。【结果】响应面分析结果表明,CSTP最佳提取条件为:液料比23∶1(mL·g^(-1)),提取温度71.6℃,提取时间4.2 h,提取率为1.31%。HPLC结果表明,CSTP-1和CSTP-2是分子量分别为9.23×10^(5)Da和4.56×10^(4)Da的均质多糖;纯化后糖醛酸含量均有所提高,其中CSTP-1的中性糖含量明显提高。红外光谱结果显示,两组分均为糖蛋白缀合物,含有吡喃环,但其分子之间存在一定结构差异。在抗氧化活性方面,CSTP-2对于各类自由基的清除能力要优于CSTP-1,且800μg·mL-1CSTP-2对·OH的清除率达90%,与抗坏血酸(Vc)相当。【结论】优化后的石佛翠多糖提取工艺可行性高,经琼脂糖凝胶CL-4B柱层析分离纯化后所得的多糖组分纯度较高且具有一定的抗氧化能力。

【Objective】Extraction of polysaccharides from Shifocui tea leaves harvested in summer and autumn were optimized and antioxidant activity of CSTP-1 and CSTP-2 fractions determined.【Method】Based upon polysaccharide extraction rate, conditions of the process were optimized by an experiment using the single factor and response surface methods. Purified polysaccharide fractions, CSTP-1 and CSTP-2 were obtained by CL-4B column chromatography on an agarose gel, and contents determined by phenol sulfuric acid and m-hydroxybiphenyl methods, molecular weight by HPLC, and antioxidant activities by scavenging rates on free radicals, DPPH· , · OH, and O^(2−). 【Results】The optimized extraction process applied a liquid to solid ratio of 23:1 (mL·g^(−1)) at 71.6℃ for 4.2 h to yield 1.31% of CSTP. The obtained homogeneous polysaccharides were CSTP-1 with a molecular weight of 9.23×10^(5) Da and CSTP-2 with a molecular weight of 4.56×10^(4) Da. The optimization significantly increased uronic acids, especially neutral sugar in CSTP-1. Both fractions of the polysaccharides were glycoprotein conjugates containing pyran rings with some structural differentiations between them, as shown by infrared spectroscopy. The free radical scavenging ability of CSTP-2 was higher than that of CSTP-1, and the activity on ·OH at 800 μg·mL^(−1) was comparable to Vc. 【 Conclusion】 The optimized polysaccharide extraction, separation, and purification developed under this study seemed highly plausible to be used for producing functional foods that would conceivably extend the utilization of Shifucui tea.