1-Methylxanthine
1-Methylxanthine is one of the major metabolites of caffeine in humans. The oxidation of 1-methylxanthine to 1-methyluric acid occurs so rapidly that the parent compound could not be detected in plasma, and only low concentrations could be detected in the brain (PMID: 28863020). 1-methylxanthine is the major metabolites of caffeine in the human. The oxidation of 1-methylxanthine to 1-methyluric acid occurred so rapidly that the parent compound could not be detected in plasma, and only low concentrations could be detected in brain. (PMID: 28863020 [HMDB] 1-Methylxanthine, a caffeine derivative, is an essential human urinary metabolite of caffeine and theophylline (1,3-dimethylxanthine, TP)[1]. 1-Methylxanthine enhances the radiosensitivity of tumor cells[2]. 1-Methylxanthine, a caffeine derivative, is an essential human urinary metabolite of caffeine and theophylline (1,3-dimethylxanthine, TP)[1]. 1-Methylxanthine enhances the radiosensitivity of tumor cells[2].