Voltammetry of the Pteridine Derivative, Triamterene

Abstract

Triamterene, 6-phenyl-2, 4, 7-triaminopteridine (1), a diuretic, gave two steps of two-electron reduction waves on Tast polarography (TP). The first step was ascribed to the reversible reduction of 1 into unreducible 5, 8-dihydrotriamterene (2) by cyclic voltammetry (CV). Tautomerization of 2 to reducible 7, 8-dihydrotriamterene (3) was rapid first-order reaction catalyzed by acid and base. The second step was attributed to the irreversible reduction of 3 into 5, 6, 7, 8-tetrahydrotriamterene (4), which was oxidized to 2, 4-diamino-6-phenylpteridine at a more positive potential than those of 2 and 3 into 1 on CV. The oxidation of 3 to 1 was observed at a more positive potential than that of 2 to 1 on CV. The anodic wave of 1 on TP in alkaline solution was ascribed to formation of the mercury complex of 1.