“…For example, caffeine (1,3,7-trimethylxanthine) and theophylline (1,3-dimethylxanthine) which are ingredients in tea, coffee, and some other beverages, are two typical natural methylxanthines and play important roles in traditional medicines . Caffeine can not only antagonize adenosine receptors and inhibit the activity of phosphodiesterase to show neurostimulatory actions, , but also be used as a vasodilator and a drug to treat renal disease. , As for theophylline, it can be adapted to treat respiratory diseases due to its bronchodilator action and is also used as a cardiac stimulator and diuretic. ,− …”