桂花不同溶剂提取物对氧自由基清除作用的ESR研究

ESR Studies on the Scavenging Effect on Oxygen Free Radicals in Different Extracts from Osmanthus Fragrans

关键词:  桂花  电子自旋共振技术  自由基

Key words:  Osmanthus fragrans  electron spin resonance  free radical

摘要:

目的 研究桂花不同提取物对氧自由基的清除作用。方法 利用不同极性溶剂(水、石油醚、乙酸乙酯、正丁醇)浸提桂花粉后得到不同极性的提取物。通过电子自旋共振(ESR)和自旋捕集技术，以1,1-二苯基-2-三硝基苯肼自由基(DPPH)及核黄素光照条件下产生超氧阴离子O₂^-自由基体系，检测桂花中各组分清除DPPH自由基及O₂^-的能力。结果 以维生素C为对照，桂花水提取物、石油醚提取物、乙酸乙酯提取物、正丁醇提取物及维生素C清除DPPH自由基能力IC₅₀分别为59.63，53.93，28.33，38.89，40.93 μg·mL^-1；各提取物及维生素C对超氧阴离子O₂^-自由基清除能力IC50分别为63.37，55.47，30.20，48.36，41.52 μg·mL^-1。其中各提取物的乙酸乙酯提取物的DPPH及O₂^-清除率最大。结论 通过比较各组分对DPPH自由基及超氧阴离子自由基的清除能力，了解桂花中抗氧化成分在各相中的分布情况，并据此进行有目的的分离桂花中的抗氧化成分。

Abstract:

OBJECTIVE To research scavenging effect on the oxygen free radicals in different extracts from Omanthus fragrans. METHODS Different polar extracts in Omanthus fragrans were obtained by different solvents such as water, petroleum ether, ethyl acetate and n-butanol. 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and superoxide anion free radical(O₂^-) produced in lactoflavin illumination system were measured by electron spin resonance(ESR) and spin trapping technology. The scavenging effects of different extracts from Osmanthus fragrans were on the DPPH free radical and superoxide anion free radical(O₂^-). RESULTS Based on vitamin C (VC) as a contrast control, aqueous layer, petroleum ether layer, ethyl acetate layer, n-butanol layer and VC whose capacities of DPPH scavenging IC50 (μg·mL^-1) were 59.63, 53.93, 28.33, 38.89, 40.93 μg·mL^-1 in turn; capacities of superoxide anion free radical(O₂^-) scavenging and VC IC50 (μg·mL^-1) were 63.37, 55.47, 30.20, 48.36, 41.52 μg·mL-1 in turn. Among them, capacities of DPPH scavenging and superoxide anion free radical(O₂^-) scavenging from ethyl acetate layer were maximum. CONCLUSION By comparison with capacities of DPPH scavenging and superoxide anion free radical(O₂^-) scavenging, the situation of distribution in each phase was known about antioxidant constituents from Osmanthus fragrans. According to the result, antioxidant constituents were isolated purposively.