High density lipoprotein (HDL) has been considered to possess antioxidant properties in addition to its antiatherosclerotic effects. Paraoxonase1 (PON1) associated with HDL has been considered to be responsible for its antioxidant potential. Present investigation aimed to study PON1 activity in relation to oxidative stress in Indian (Punjabi) population suffering from coronary artery disease (CAD). Significantly reduced serum PON1 activity was observed in CAD patients compared to normal individuals. Reduced PON1 activity was also observed in CAD positive diabetics, hypertensives, smokers and alcoholics in comparison to CAD negative diabetics, hypertensives, smokers and alcoholics and controls. Activity of PON1 varies significantly among patients in different risk groups, may be leading to different susceptibility towards disease development and its progression in various CAD risk factors. Patients were also having increased oxidative stress as indicated by their significantly raised serum MDA levels. Significant variation in serum MDA levels was also observed in different risk groups. Of all the risk factors, smoking was associated with highly reduced PON1 activity and significantly raised serum MDA levels. A significant negative coefficient of correlation (r2 0.71) was observed between serum PON1 activity and serum MDA levels. Activity of another antioxidant enzyme i.e. superoxide dismutase (SOD) was also reduced in CAD patients. However SOD activity did not vary significantly among patients in different risk groups. Depressed PON1 activity in CAD patients may reduce their ability to protect LDL from oxidation. In conclusion, significantly reduced paraoxonase1 activity has been associated with CAD and its various risk factors in Indian (Punjabi) population. Smoke may extensively modify serum PON1 activity in a negative direction.
Keywords: Coronary artery disease (CAD), CAD risk factors, paraoxonase1, oxidative stress
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