Answer: purine

AnswerCrossword Clue
PURINECompound whence caffeine is derived
purineone of several purine derivatives, esp. the bases adenine and guanine, which are fundamental constituents of nucleic acids
purinewhite, crystalline compound, C5H4N4, from which is derived a group of compounds including uric acid, xanthine, and caffeine
purinea chemical compound, also PURIN