Glutathione

Glutathione is the most abundant intracellular thiol antioxidant, serving as the primary cellular defense against oxidative stress. It directly scavenges reactive oxygen species and serves as a cofactor for glutathione peroxidases and glutathione-S-transferases. The reduced thiol group on its cysteine residue donates electrons to neutralize ROS and electrophilic toxins. Glutathione also maintains vitamins C and E in their reduced (active) forms, regulates the nitric oxide cycle, and is essential for immune cell function, particularly T-lymphocyte proliferation.