Primapterin, anapterin, and 6-oxo-primapterin, three new 7-substituted pterins identified in a patient with hyperphenylalaninemia.

Three unknown compounds present in the urine of a patient with mild hyperphenylalaninemia were identified to be L-erythro-7-iso-biopterin, D-erythro-7-iso-neopterin, and L-erythro-6-oxo-7-iso-biopterin. The newly identified pterins were named primapterin, anapterin, and 6-oxo-primapterin, respectively. Primapterin and anapterin are present in very low concentrations in every human urine, as well as in the liver of man and mouse, whereas 6-oxo-primapterin was detected in the patient's urine only. Substantial amounts of primapterin were excreted in the patient described. The metabolic origin of primapterin and anapterin is still obscure.