porphyrinogen /por″f-rin′o-jen/ , the reduced form of a porphyrin. The porphyrinogens are the functional intermediates in the biosynthesis of heme. If oxidized to their corresponding porphyrins, such as occurs in porphyrias, they are irreversibly removed from the biosynthetic pathway and accumulate in tissue. Their nomenclature corresponds to that of the porphyrins.
