Abstract
Vitamin E, having the well known antioxidant activity through scavenging free radicals و it occurs in several isomeric forms , these isomers have relatively different functions . One of these actions is related to its ability to inhibit platelets aggregation and hence thrombosis. The present study included a total number of apparently healthy 62 males . 11of them served as standard group , treated with 100 mg aspirin /day for more than one month . Another 31 subjects were randomly grouped into 5 groups that received different daily doses of α – tocopherol : 400 IU , 800 IU and 1200 IU for 2-6 months.The remainder ( 20 ) subjects served as a control group ( received no therapy ) . Platelets function was assessed based on measuring bleeding time and Slide Platelets Aggregation Time ( SPAT ) Meanwhile , thiobarbituric acid reactive substances (TBARS) were measured as a marker for oxidative stress. The results showed that the commercially available vitamin E preparations (α- tocopherol ) could exert anti-coagulant effect ,such effect is more dependant on duration of therapy , rather than dose related action .In addition to it’s antioxidant effect, which seems to be significantly correlated to it’s antiplatelets effect ( r=0.994 ,p<0.05).Hence , long term administration of high doses of vitamin E could be effective in decreasing the incidence of thrombosis ,which in turn depends on platelets function. Such effect might not affect bleeding time obviously , but it could reduce chances for platelets recruitment , which might represent an additional advantageous action for vitamin E over other antioxidants.
 Key Words : Vitamin E , α - Tocopherol , Antiplatelets
Highlights
Vitamin E has been known as an essential nutrient to maintain normal reproduction since 1922 [1].The large scale studies have shown an inverse correlation between its high dietary intake and the incidence of coronary heart diseases ( 2,3 )
One of the proposed mechanisms for vitamin E antiplatelet activity could be through its interference with vitamin K activity with subsequent disturbance of the cascade of reactions for clot formation,that predispose to thrombosis
Platelets -derived NO has been found to inhibit platelets aggregation and to reduce recuiment to grow to thrombus [27] .Incorporationofα– tocopherol might increase NO producion in platelets by its free radicals scavenging activity and by preventing NO quenching by peroxyl radicals ( 28,29 )
Summary
Vitamin E has been known as an essential nutrient to maintain normal reproduction since 1922 [1].The large scale studies have shown an inverse correlation between its high dietary intake and the incidence of coronary heart diseases ( 2,3 ). These studies did not provide sufficient evidences , that vitamin E administration can prevent cardiovascular events , nor the subsequent cardiac deaths(4 ). Vitamin E occurs as a family of eight members , four of them are referred to as tocopherols and the other four members are known as trienols Both tocopherols and tocotrienols are subdivided into 4 types : alpha (α), beta ( β) , gamma ( γ) and delta(δ) , according to their substitutions on the molecule[7],as shown in figure [1] and table 1.
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Schedule a callMore From: Iraqi Journal of Pharmaceutical Sciences ( P-ISSN: 1683 - 3597 , E-ISSN : 2521 - 3512)
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