Siriraj Med J, Volume 66, Number 2, March-April 2014 42 OriginalArticle A INTRODUCTION cetylsalicylic acid, known as aspirin, was intro- duced in the late 1890s. Despite its well-known analgesic and antipyretic effects, the antiplatelet activity of this agent was recognized almost 70 years later. Aspirin is known to reduce the incidence of thrombotic occlusive events such as myocardial infarction and stroke. Low dose aspirin is frequently prescribed for primary prevention to reduce the risk of cadiovascular disease. The benefts of low dose aspirin therapy are well established and a recent meta-analysis of more than 50,000 women and 40,000 men taking part in six randomized trials indicated that low dose aspirin usage is associated with Effects of Aspirin on Serum Total Antioxidant Activity in A Short Term Period Mehmet H. Koseoglu, M.D.*, Serap Cuhadar, M.D.*, Aysenur Atay, M.D.*, Yavuz Yigit, M.D.*, Yasemin Akcay, M.D.**, Eser Sozmen, M.D.** *Department of Biochemistry and Clinical Biochemistry, Ataturk Training and Research Hospital, Izmir, Turkey, **Department of Biochemistry, Ege University Medical Faculty, Izmir, Turkey. Correspondence to: Serap Cuhadar E-mail: sdcuhadar@yahoo.com Received 29 March 2013 Revised 16 August 2013 Accepted 21 August 2013 ABSTRACT Objective: Aspirin is generally used in the prevention of thrombotic occlusive events such as coronary heart disease and stroke. Underlying mechanism of action is that aspirin inhibits platelets by irreversibly inactivating cyclooxygenase-1, thereby blocking the generation of thromboxane A 2 which is a potent vasoconstrictor and platelet agonist. Aspirin may also help to decrease the progression of atherosclerosis by its antioxidant effect in addition to its inhibiting effect on the coagulation sys- tem. The aim of this study was to examine the antioxidant effect of low-dose aspirin supplementation in a short term period. Methods: Ten healthy volunteers were enrolled in the study. Low-dose aspirin (300 mg. daily for 10 days) was given orally to subjects. Serum specimens were taken after 12-14 hr fasting as baseline and at 4 th hr and 10 th day of the oral aspirin supplementation. Serum total antioxidant activity (AOA), ferritin, iron, total cholesterol, LDL cholesterol, HDL cholesterol and triglycerides were measured. Results: Serum AOA at 4 th hr were found signifcantly higher in comparison to baseline levels (p=0.006), but no signifcant difference was determined on the 10 th day. There were no signifcant differences among baseline, 4 th hr and 10 th day values for the remaining parameters. Conclusion: Our results suggest that low-dose aspirin supplementation rapidly increases total antioxidant activity. Aspirin may play a role in improving the general antioxidative potency of the body. Keywords: Aspirin, ferritin, total antioxidant activity Siriraj Med J 2014;66:42-44 E-journal: http://www.sirirajmedj.com a signifcant reduction in cardiovascular events in both women and men. 1 This effect is considered to be due to the platelet inhibitory action of aspirin, which results from irreversible inhibition of platelet cyclooxygenase activity and thromboxane A 2 formation. Thromboxane A 2 is a potent agonist and mediator of vascular smooth muscle contraction and platelet aggregation. However, recently aspirin has been shown to have free radical scavenging and antioxidant properties. 2-4 It is reported that aspirin protects LDL from oxidative modifcation, 5 endothelial cells of the vascular wall from damage caused by oxygen radicals, 6-9 and also prevents proteins from oxidation by acetylation of the amino groups of lysine residues or scavenging hydroxyl radicals. 10 Tuomainen et al, 11 have shown that subjects with depleted levels of iron also have a lowered risk of athero- sclerosis and myocardial infarction. Furthermore, Oberle et al, 7 demonstrated that aspirin at therapeutically relevant concentrations is capable of activating synthesis of ferri- tin in bovine pulmonary artery endothelial cells. They