The occurrence of substituted uric acids in human urine

Abstract

Substituted uric acids were isolated from the urine of a human subject on a normal diet. The positions of substituent groups were determined by comparison with known synthetic methyluric acids, using spectroscopic and other methods. Results indicate that these isolated compounds are also methyluric acids substituted in the 7-, 1- and 1,7-positions. These compounds were shown to be metabolic products of exogenous methylxanthines, i.e. caffeine, theobromine or theophylline. Demethylation during metabolism of these compounds can occur in the 3-, 1- and 7-positions, but no definite order of stability was demonstrated.