. . . "experimental"@en . . . . . . . . . . . . . . . . . . . . . . . . . . "A cyclized derivative of L-GLUTAMIC ACID. Elevated blood levels may be associated with problems of GLUTAMINE or GLUTATHIONE metabolism. [PubChem]"@en . . "John G. Black, Ian R. Scott, \"Pyroglutamic acid esters, their synthesis and use in topical products.\" U.S. Patent US4774255, issued December, 1974."@en . "98-79-3"@en . . "Pyroglutamic Acid"@en . . . . . . . .