Chemical characterization of peroxidized low-density lipoprotein in plasma and aortic atheroma

Hydroperoxidized cholesteryl linoleate (HPO-CL, spot X1) was produced by peroxidation of normal LDL isolated from plasma of healthy persons. Spot X stained on thin-layer chromatography plate (silica 60) between triglycerides and free fatty acids. The solvent mixture used consisted of petroleum ether 75, ethyl ether 25, and acetic acid 1. Spot X1 of plasma from healthy subjects stained slightly. It was also identified in plasma LDL of patients with atherosclerotic diseases, and in total lipids extracted from aortic atheroma obtained at autopsy. Whereas spot X1 obtained from plasma LDL of patients with atherosclerotic diseases consisted of HPO-CL, spot X1 obtained from aortic atheroma was reduced HPO-CL (hydroxide CL). Spot X1 of obtained from aortic atheroma was reduced HPO-CL (hydroxide CL). Spot X1 of aortic atheroma did not react to p-methoxydiphenylpyrenylphosphine (MP3)-an agent which shows only positive reaction to hydroperoxide chemical structures-although spot X1 of plasma LDL from atherosclerotic diseases reacted positively to MP3. Moreover, spot X1 obtained from aortic atheroma showed the same Rf value as that of the reduced HPO-CL. The IR profile of spot X1 obtained from aortic atheroma was similar to that of hydroxide CL, although the IR profiled HPO-CL was similar to that obtained from plasma LDL of atherosclerotic patients. In addition, HPO-CL was not recognized in the LDL fraction with clathrin-coated pits from aortic atheroma.