Glutathione

Glutathione is the predominant non-protein thiol and functions as an intracellular redox buffer and antioxidant.
Glutathione is a nucleophilic scavenger and an electron donor. Its reducing ability lies with maintaining molecules such as ascorbate (vitamin C) and proteins in their reduced state.
Glutathione is also a cofactor for the selenium-containing glutathione peroxidases, which are major antioxidant enzymes. Additional actions may include Immunomodulatory activities and beneficial effects on sperm motility primarily due to its antioxidant activity