- A crystalline compound closely linked to xanthin, contained in little amounts in urine.
- A crystalline substance closely regarding xanthin, present in small quantity in urine.
- A poisonous crystalline base, 1, 7-dimethylxanthin, C7H8O2N4, which occurs in real human urine. It may be produced from theobromine and became caffein. It melts at 284° C.