We assessed the
antioxidant status and contents of unoxidized and oxidized
lipids in freshly obtained, homogenized samples of both normal human iliac arteries and carotid and femoral
atherosclerotic plaque. Optimal sample preparation involved homogenization of human
atherosclerotic plaque for 5 minutes, which resulted in recovery of most of the unoxidized and oxidized
lipids without substantial destruction of endogenous
vitamins C and E and 87% and 43% recoveries of added standards of
alpha-tocotrienol and isoascorbate, respectively. The total
protein,
lipid, and
antioxidant levels obtained from human plaque varied among donors, although the reproducibility of replicates from a single sample was within 3%, except for ubiquinone-10 and ascorbate, which varied by 20% and 25%, respectively. Plaque samples contained significantly more ascorbate and
urate than control arteries, with no discernible difference in the
vitamin C redox status between plaque and control materials. The concentrations of
alpha-tocopherol and ubiquinone-10 were comparable in plaque samples and control arteries. However, approximately 9 mol percent of plaque
alpha-tocopherol was present as alpha-
tocopherylquinone, whereas this oxidation product of
vitamin E was not detectable in control arteries.
Coenzyme Q10 in plaque and control arteries was only detected in the oxidized form ubiquinone-10, although
coenzyme Q10 oxidation may have occurred during processing. The most abundant of all studied
lipids in plaque samples was free
cholesterol, followed by
cholesteryl oleate and
cholesteryl linoleate (Ch18:2). Approximately 30% of plaque Ch18:2 was oxidized, with 17%, 12%, and 1% present as fatty acyl
hydroxides,
ketones, and hydroperoxides, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)