An aminopyrimidine antibiotic whose structure consists of pyrimidine 2,4-diamine and 1,2,3-trimethoxybenzene moieties linked by a methylene bridge. ChEBI: Trimethoprim is an aminopyrimidine antibiotic whose structure consists of pyrimidine 2,4-diamine and 1,2,3-trimethoxybenzene moieties linked by a methylene bridge. It has a role as an EC 1.5.1.3 (dihydrofolate reductase) inhibitor, a xenobiotic, an environmental contaminant, a drug allergen, an antibacterial drug and a diuretic. It is a member of methoxybenzenes and an aminopyrimidine.