Yu Liangli, Adams Dwayne, Gabel Michael
Department of Food Science and Human Nutrition, Colorado State University, Fort Collins, Colorado 80523-1571, USA.
J Agric Food Chem. 2002 Jul 3;50(14):4135-40. doi: 10.1021/jf020086a.
Conjugated linoleic acid (CLA) isomers were investigated for free radical scavenging properties against the stable 2,2-diphenyl-1-picryhydrazyl radical (DPPH(*)) by electron spin resonance (ESR) spectrometry and spectrophotometric methods. ESR measurements confirmed that both c9,t11-CLA and t10,c12-CLA directly reacted with and quenched DPPH radicals, whereas spectrophotometric analysis demonstrated that c9,t11-CLA and t10,c12-CLA differed in their kinetic and thermodynamic properties in reacting with DPPH radicals. t10,c12-CLA was shown to exhibit a greater initial velocity in CLA-DPPH radical reactions at levels of 2.5-80 mg/mL, and c9,t11-CLA scavenged more DPPH radicals at steady state. Similar dose and time relationships were observed for both isomers. In addition, a mixture of c9,t11- and t10,c12-CLA isomers demonstrated a greater initial velocity in quenching DPPH radicals than either isomer alone on the same concentration basis, suggesting that a synergistic effect between CLA isomers existed in their reactions with DPPH radicals. These results support the conclusion that individual CLA isomers differ in their biological actions and indicate that interaction(s) between isomers may contribute to their beneficial effects.
通过电子自旋共振（ESR）光谱法和分光光度法，研究了共轭亚油酸（CLA）异构体对稳定的2,2-二苯基-1-苦基肼自由基（DPPH(*)）的自由基清除特性。ESR测量证实，c9,t11-CLA和t10,c12-CLA均能直接与DPPH自由基反应并将其淬灭，而分光光度分析表明，c9,t11-CLA和t10,c12-CLA在与DPPH自由基反应时的动力学和热力学性质存在差异。结果表明，在2.5-80 mg/mL的浓度范围内，t10,c12-CLA在CLA-DPPH自由基反应中表现出更高的初始反应速率，而c9,t11-CLA在稳态时清除的DPPH自由基更多。两种异构体均观察到类似的剂量和时间关系。此外，在相同浓度基础上，c9,t11-和t10,c12-CLA异构体的混合物在淬灭DPPH自由基方面表现出比单独任何一种异构体更高的初始反应速率，这表明CLA异构体之间在与DPPH自由基的反应中存在协同效应。这些结果支持了CLA异构体的生物学作用存在差异这一结论，并表明异构体之间的相互作用可能有助于其产生有益效果。
