From the 2003 FDA Science Forum
J.J.Yin1, M.M.Mossoba1, M.P.Yurawecz1, Y.Ku1, J.K.Kramer2, 1FDA, College Park, MD., 2Southern Crop ProtectiFood Research Center, Ontario, Canadaon,
Conjugated linoleic acid (CLA) isomers are found in dairy products and meats from ruminants and reportedly exhibited anticarcinogenic and other beneficial physiological effects in animal studies. The effect of CLA on the relation between structure and function of membranes is described in this work. Electron spin resonance (ESR) spin-label oximetry was used to evaluate if oxygen transport and oxygen depletion was affected by incorporation of CLA instead of linoleic acid (LA) into membrane phospholipids. Specifically, 1-stearoyl-2- (9cis, 11trans-octadecadienoyl)-phosphatidylcholine (C9T11 CLA) and 1-stearoyl-2-(10trans, 12cis-octadecadienoyl)-phosphatidylcholine (T10C12 CLA) were incorporated into soy plant phosphatidylcholine (Soy PC), egg yolk PC (EYPC), Heart PC and Brain PC bilayers. Moreover, the use of spin labels attached to different carbons along the fatty acid chain makes it possible to carry out structural and oximetric determinations with the same test sample. In our model system, free radical generation was initiated by extended incubation of the liposomes, induction by AAPH, and AMVN. The effects on the oxygen consumption rate of 5 mol% CLA in most PC was significantly larger compared to the 5 mol% LA. However, there is no significant difference in homogenous solutions of those lipids. The perturbation of membrane structure and the increase of the relative oxygen diffusion-concentration products provided a potential mechanism by which CLA incorporated into membrane lipids could affect oxidative stress.