Plasma malondialdehyde, bilirubin, homocysteine and total antioxidant capacity in patients with angiographically defined coronary artery disease
Oxidative stress has been implicated in coronary artery disease (CAD). Malondialdehyde (MDA) is lipid peroxidation end product. Bilirubin may act as an antioxidant that suppresses lipid oxidation. The role of MDA and antioxidant capacity and their inter-relationship in patients with and without CAD was investigated. Thirty-eight consecutive patients with angiographically diagnosed CAD were compared with 60 age, and sex-matched controls. The controls had completely normal coronary arteries in angiograms. Plasma MDA, serum bilirubin, total homocysteine and total antioxidant capacity (TAC) levels were measured. Risk factors of CAD were determined for all subjects using National Cholesterol Education Program (NCEP)-Adult Treatment Panel (ATP)-III criteria. Serum MDA and total homocysteine concentration were significantly higher, but TAC, total bilirubin and direct bilirubin levels were lower in CAD patients when compared to the controls. Age, and sex-adjusted plasma MDA levels had negative correlations with TAC (r = -0.30, p = 0.001) and total bilirubin (r = -0.30, p = 0.002) concentrations. In multivariate analysis by the multiple logistic regression method, serum MDA was significantly associated with CAD (OR = 1.15, 95% CI, 1.25 to 1.82; p < 0.0001)) after adjustment for lipid status parameters and traditional risk factors in this study population. Increased serum MDA concentration, as a biomarker of lipid peroxidation, low serum bilirubin and antioxidant capacity were observed in patients with angiographically defined CAD. The significant inverse correlation of the serum bilirubin and MDA levels demands further in-depth investigations to clarify the association between them in the development of CAD.
Key words: Oxidative stress, bilirubin, malondialdehyde, coronary artery disease, antioxidant capacity, homocysteine.