香椿叶提取物不同极性部位体外抗氧化活性研究

Studies on Antioxidative Activities in Vitro of Different Polarity Fractions of Extract from Toona Sinensis Leaves

目的:研究香椿叶提取物不同极性部位的体外抗氧化活性。方法:采用有机溶剂萃取法将香椿叶提取物分为石油醚相、氯仿相、乙酸乙酯相、正丁醇相和水相等5个不同极性部位,考察其总抗氧化力(TAC)及对羟自由基(·OH)、超氧自由基(O2·-)、DPPH自由基(DPPH·)和脂质过氧化产物丙二醛(MDA)的清除效果,比较香椿叶提取物不同极性部位的抗氧化作用。结果:香椿叶提取物的不同极性部位均有抗氧化活性,呈显著剂量效应关系;其抗氧化效果因反应体系的不同而不同,且不同极性部位的抗氧化活性有差异。乙酸乙酯相和正丁醇相的TAC较氯仿相强,石油醚相和水相的TAC较小,乙酸乙酯相对·OH、O2·-及DPPH·的清除能力和抗脂质过氧化效果均好于L-抗坏血酸。结论:香椿叶提取物的乙酸乙酯相和正丁醇相的抗氧化作用强,是天然抗氧化剂的良好来源,应对其进一步分离纯化。

Objective:To investigate antioxidant activities in vitro of different polarity fractions of extract from Toona Sinensis leaves.Methods:5 extracts were obtained in different fractions by using different polarities of solvents such as petroleum ether,chloroform,ethyl acetate,normal butyl alcohol.According to their total antioxidant activities(TAC) and scavenging activities for hydroxyl radicals(·OH),superoxidized radicals(O2·-),1,1-diphenyl-2-picrylhydrazyl(DPPH)radicals and malondialdehyde(MDA)generated by lipid peroxidation,antioxidant activities of different polarity fractions were compared.Results:Different polarity fractions of extract from Toona Sinensis leaves were showed antioxidant activities,and existed marked concentration-effect relationships.5 fractions all had different antioxidant effects in different reaction systems.There were differences in antioxidant activities among 5 fractions.TAC followed the order of ethyl acetate fraction>normal butyl alcohol fraction>chloroform fraction>petroleum ether fraction>water fraction.Ethyl acetate fraction had better scavenging effects than L-ascorbic acid for ·OH,O2·-,DPPH· and MDA.Conclusions:Ethyl acetate fraction and normal butyl alcohol fraction,which were a kind of good source for natural antioxidants,showed relatively strong antioxidant activities,and were worth separating and purifying further.