Pyroglutamic acid

Pyroglutamic acid (5-oxoproline) is an intermediate of the γ-glutamyl cycle of glutathione synthesis and turnover, accumulating when glutathione demand outstrips cysteine or glycine availability. Salivary pyroglutamic acid reflects the strain on the glutathione antioxidant system that defends tissues against exercise-induced reactive oxygen species. Sen et al. (1994) characterised the central role of glutathione redox status in exercise-induced oxidative stress and endurance.