Answer: glutathione

AnswerCrossword Clue
glutathionecrystalline, water-soluble peptide of glutamic acid, cysteine, and glycine, C10H17N3O6S, found in blood and in animal and plant tissues, and important in tissue oxidations and in the activation of some enzymes
glutathionean antioxidant, found in the body's airways and nose, that protects the lungs from the effects of pollutants