Theobromine, caffeine and theophylline are zanthine methylium derivates. They have the similar mother structure, but different on the number of replaced methylium and its place. 可可碱(Theobromine)、咖啡因(Caffeine)、茶碱(Theophylline)是黄嘌呤甲基衍生物,它们的母体结构相同,只是甲基取代基的数目和位置不同。