Free radical induced redox reactions of 2,4,6-triaminopyrimidine: A pulse radiolysis study

Abstract

Kinetics and mechanism of reactions of 2,4,6-triaminopyrimidine (TAP) with some free radicals have been studied using pulse radiolysis technique. TAP has been found to react with hydrated electron (3.1 × 108 M−1 s−1), hydroxyl radical (4.0 × 109 M−1 s−1), trichloromethyl peroxyl radical (1.1 × 108 M−1 s−1), and sulfate radical (4.5 × 109 M−1 s−1). Density functional calculations have been performed to assign absorption maxima of transients produced on oxidation of TAP as: TAP•+ radical cation (~ 430, ~ 600, ~ 720 nm), TAP(C5)• radical (~ 300, ~ 320 nm), aminyl TAP(NH)• radical (~ 300, ~ 340, ~ 440 and ~ 520 nm) and TAP-OH• radical adduct (640 nm). Almost 72% of TAP transients produced with hydroxyl radical have been found to be oxidizing in nature, which react with tyrosine (8.0 × 107 M−1 s−1), glutathione (1.2 × 108 M−1 s−1) and bovine serum albumin protein (7.8 × 108 M−1 s−1).