Distribution of antioxidants among blood components and lipoproteins: Significance of lipids/CoQ10 ratio as a possible marker of increased risk for atherosclerosis

Total CoQ₁₀ levels were evaluated in whole blood and in plasma obtained from a group of 83 healthy donors. Extraction with light petroleum ether/methanol was more efficient, for whole blood, than the extraction which is often used for plasma and serum, i.e., ethanol hexane. An excellent correlation was present between plasma CoQ₁₀ and whole blood CoQ₁₀. CoQ₁₀ is mainly associated with plasma rather than with cellular components. Positive, significant correlations were found between the LDL- chol/CoQ₁₀ ratio and the total-chol/HDL-chol ratio, which is usually considered a risk factor for atherosclerosis. The proportion of CoQ₁₀ carried by LDL was 58 ± 10%, while the amount carried by HDL was 26 ± 8%. In VLDL + IDL CoQ₁₀ was 16 ± 8%. The content of CoQ₁₀ in single classes of lipoproteins is strictly correlated with CoQ₁₀ plasma concentration. In a parallel study conducted on a population of diabetic patients (one IDDM group and one NIDDM) CoQ₁₀ plasma levels were generally higher compared to the control group, also when normalised to total cholesterol. In particular the LDL fraction showed a CoQ₁₀/chol ratio higher in NIDDM but not in IDDM patients, compared to controls. The CoQ₁₀/triglycerides ratio was lower in NIDDM respect to controls and even lower in IDDM patients.