Pharmaceutical Grade Glutathione. Intracellular Antioxidant. Gluten Free. Value Size. Glutathione is the most abundant intracellular thiol (sulfur-containing compound) and low molecular weight tripeptide found in living cells. Thiols such as glutathione alpha lipoic acid and NAC are powerful sulfur-bearing antioxidants. The antioxidant functions of Glutathione Reduced include recycling vitamins E and C and serving as a critical nucleophilic scavenger to block free radical damage to all types of tissues.