A prodrug having antioxidant activity, including a phosphorylated compound having a thiol group. A method of treating oxidative stress by administering a prodrug of a phosphorylated compound including a thiol group, removing a phosphate group of the prodrug, and treating oxidative stress. A method of increasing bioavailability of a thiol compound by creating a prodrug by phosphorylating a thiol compound, administering the prodrug, preventing first pass metabolism of the prodrug, removing a phosphate group from the prodrug, and providing active drug to a site in need of therapy from oxidative stress. A method of preventing radiation damage to healthy tissue by administering a prodrug comprising a phosphorylated compound including a thiol group, removing a phosphate group of the prodrug to provide active drug, and preventing radiation damage to healthy tissue.