3,7-Dimethyluric acid (3,7-DMU, 3,7-Dimethyl-2,6,8-trihydroxypurine), a purine derivative, is a dimethylated uric acid. It has a pyrimidine ring fused to an imidazole ring. Mechanism of the transformation of theobromine to 3,7-DMU in rat liver microsomal incubations has been investigated. 3,7-Dimethyluric acid is a primary theobromine (TB; 3,7-dimethylxanthine) metabolite. Electrochemical oxidation of 3,7-dimethyluric acid gives two voltammetric oxidation peaks (Ia and IIa) at a pyrolytic graphite electrode in aqueous solution.