Vitamin E radical reaction with antioxidants in rat liver membranes

The Japanese herbal medicine Sho-saiko-to-go-keishi-ka-shakuyaku-to (TJ-960) has been demonstrated to have an antioxidant action by quenching free radicals. The effects of TJ-960 on the tocopheroxy radicals generated by an arachidonic acid and lipoxygenase oxidation system were compared with those of the ascorbate and glutathione in vitamin E-enriched rat liver microsomes and submitochondrial membrane particles (SMP). Using electron spin resonance spectrometry, the disappearance of the tocopheroxy radicals after addition of glutathione and ascorbate was detected in microsomes and SMP, withh ascorbate displaying a more potent action than glutathione. Addition of TJ-960 demonstrated a similar effect on the tocopheroxy radicals in microsomes and SMP. In the presence of TJ-960, ascorbate, and glutathione, the loss of vitamin E in the vitamin E-enriched microsomes of rat liver undergoing oxidation was slowed down. In this paper, we introduced TJ-960 as another replenisher of vitamin E in membrane, increasing the membrane's resistance against oxidative damage.     

Interaction of vitamin C and vitamin E during free radical stress in plasma: An ESR study

To study the interaction of the antioxidant vitamins C and E in a biological system, we used electron spin resonance (ESR) spectroscopy to make serial measurement of ascorbate tocopheroxyl free radicals in plasma subjected to continuous free radical-mediated oxidative stress. Upon initiation of a continuous oxidative stress, we observed an immediate increase in the concentration of ascorbate radical, which reached a peak, and then steadily declined. Only after the virtual disappearance of the ascorbate radical did we observe the appearance of the tocopheroxyl radical. These data are consistent with the hypothesis that ascorbate is the terminal small-molecule antioxidant in biological systems. This is the first experimental demonstration that the predicted thermodynamic hierarchy of ascorbate, -tocopherol, and their free radicals holds in a biological system containing endogenous levels of these antioxidant vitamins.