[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 O2-.[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 9.23×105 Da and CSTP-2 with a molecular weight of 4.56×104 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.
关键词
石佛翠茶树/鲜叶/茶多糖/响应面法/分离纯化/抗氧化活性
Key words
Shifocui tea/fresh leaves/tea polysaccharides/response surface method/process optimization/isolation and purification/antioxidant activity