Serum pro-oxidant-antioxidant balance and low-density lipoprotein oxidation in healthy subjects with different cholesterol levels.

In this study, we investigated serum pro-oxidantantioxidant balance in 210 healthy subjects divided into groups with low and high atherogenic risk according to the levels of serum total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) and high-density lipoprotein- cholesterol (HDL-C). Diene conjugate (DC), malondialdehyde (MDA), polyunsaturated fatty acid (PUFA), vitamin E, and vitamin C levels and antioxidant activity (AOA) were determined in the serum. Endogenous DC and copper-induced MDA levels were also measured in the LDL fraction isolated by precipitation with buffered heparin from plasma in 80 healthy subjects with different serum LDL-C levels. Subjects with a high atherogenic risk had significantly higher plasma DC, MDA, and PUFA levels, but lower vitamin E/TC values and AOA than subjects with low atherogenic risk. Endogenous DC and copper-induced MDA levels in the LDL fraction were increased in subjects with serum LDL-C levels higher than 4.14 mM compared with those with normal LDL-C levels. In conclusion, this study clearly indicates that a disturbance in serum pro-oxidant-antioxidant balance and an increase in LDL oxidation are concomitant with higher TC and LDL-C and lower HDL-C levels in the serum.