Alpha-mangostin induces changes in glutathione levels associated with glutathione peroxidase activity in rat brain synaptosomes.
In a previous report, we have characterized the antiperoxidative properties of alpha-mangostin in different toxic models tested in nerve tissue preparations. Here, the modulatory effects of this xanthone on the glutathione system (reduced glutathione (GSH) levels, glutathione peroxidase (GPx), and glutathione S-transferase (GST) activities) were tested in synaptosomal P2 fractions isolated from rat brains in order to provide further information on key mechanisms exerted by this antioxidant in the nervous system. Synaptosomes were exposed to increasing concentrations of the xanthone, and also challenged to the toxic actions of a free radical generator, ferrous sulfate (FeSO(4)). For comparative purposes, the mitochondrial toxin 3-nitropropionic acid (3-NP) was also explored. Alpha-mangostin significantly decreased the levels of GSH, and increased GPx activity. This finding was interpreted as a modulatory action of the GSH system in preparation to exert antioxidant responses. Although FeSO(4) exhibited similar effects, these were interpreted as a compensatory response to the toxic actions of the pro-oxidant. We came to this conclusion based on our previous report where alpha-mangostin produced antiperoxidative effects and FeSO(4) produced oxidative damage to lipids. GST activity remained unaffected by both the antioxidant and the pro-oxidant. Our results suggest that alpha-mangostin is able to modulate GPx activity as a potential antioxidant strategy, thereby transiently consuming GSH levels.