ABSTRACT
The current study was carried out to investigate the effects of the excessive use of large doses of the most widely used antioxidants, d-alpha-tocopherol [vitamin E], retinol acetate [vitamin A], and l-ascorbic acid [vitamin C], on the blood hemostasis. 140 albino rats were divided into 4 experimental groups of 40 animals each as follows: Group I: A control group [negative and positive]; Group II: Each animal of this group received a daily oral dose of 24 mg of d-alpha-tocopherol; Group III: Each animal of this group received a daily oral dose of 1mg of Trans-retinol acetate, and; Group IV: Each animal of this group received a daily oral dose of 20 mg of l-ascorbic acid. The results of the current study have revealed that both d-alpha-tocopherol and retinol acetate produced a significant prolongation of prothrombin time [PT] and activated partial thromboplastine time [PTT] with a significant reduction of factor X activity. On the contrary, l-ascorbic acid produced no significant effect on these parameters. Histopathological examination of liver, kidney, and brain specimens of the different treated animal groups revealed the presence of significant hemorrhages in most samples of both d-alpha-tocopherol- and retinol acetate-treated animals, while the specimens of l-ascorbic acid-treated animals showed no hemorrhage in nearly all samples. These histopathological changes were confirmatory to the biochemical ones. It could be concluded that the excessive use of large doses both d-alpha-tocopherol and retinol acetate alters the blood hemostasis with increased bleeding tendencies, while l-ascorbic acid doesn't. In fact, l-ascorbic acid could be considered a safe drug even in excessive doses for long periods