. . . . . "experimental"@en . . . . . . . . . . . . . . . . . . . . . . . . . . . "2009-64-5"@en . "Neopterin"@en . . "A pteridine derivative present in body fluids; elevated levels result from immune system activation, malignant disease, allograft rejection, and viral infections. (From Stedman, 26th ed) Neopterin also serves as a precursor in the biosynthesis of biopterin. [PubChem]"@en . . . .