4,5-dihydroxy-3,7-dimethyl-9H-purine-2,6,8-trione

1-[2-(3,7-dimethyl-2,6-dioxopurin-1-yl)ethyl]-3,7-dimethylpurine-2,6-dione

氟氯西林

2-氯-7-甲基-3H-嘌呤-6-硫酮

1-benzyl-3,7-dimethylpurine-2,6-dione