广林9号桉叶多酚抗氧化活性研究

采用不同极性有机溶剂对广林9号桉叶提取物进行系统萃取分离，用福林-酚法测定各组分的总酚含量，以1,1-二苯基-2-三硝基苯肼(DPPH)、2,2＇-联氮-双-(3-乙基苯并噻唑啉-6-磺酸)(ABTS)、还原能力3种体外抗氧化活性方法测定了桉叶各组分的抗氧化活性。结果表明，不同萃取组分中，乙酸乙酯组分总酚含量最高，达到502.67mg/g；其对DPPH自由基和ABTS＋·的清除能力和还原能力也最强，优于阳性对照物茶多酚，其清除两种自由基的IC50分别为0.097mg/mL 和0.034mg/mL；通过总酚含量与抗氧化活性比较发现，其抗氧化活性与总酚含量成正相关，由此判断桉叶提取物的抗氧化活性成分主要为多酚类物质；桉叶粗提物中多酚含量达到30%以上，与茶叶粗提物中多酚含量相当，具有开发意义。

Antioxidant Activity of Polyphenol Extracts from Leaves of E. grandis × E. urophylla Guanglin No. 9

Crude ethanol extract from the leaves of E.grandis×E.urophylla Guanglin No.9 was fractionated by repeated extractions sequentially with solvents of different polarity into petroleum ether-soluble,chloroform-soluble,ethyl acetate-soluble,n-butanol-soluble fractions and residue.Total phenolic contents in the six samples were determined by Folin-Ciocalteu method.Meanwhile,their antioxidant activity was tested by in vitro ABTS,DPPH and FRAP assays.The results indicated that among the samples,the ethyl acetate-soluble fraction showed the highest total phenolic content,502.67 mg/g,and the strongest ABTS and DPPH scavenging activity and reducing power activity,which were better than those of VC.The IC50 values of the fraction against DPPH and ABTS radicals were 0.097 mg/mL and 0.034 mg/mL,respectively.Moreover,a positive correlation between total phenolic content and antioxidant activity was observed for all the samples.This indicates that polypehnolics are mainly responsible for their antioxidant activity.The crude ethanol extract exhibited a total phenloic content(over 30%) similar to that of its counterpart from tea.This study demonstrates that the crude ethanol extract has a high exploitation potential.