n.crystalline oxidation product of the metabolism of nucleoproteins; precursor of uric acid; found in many organs and in urine

1. Xanthines such as caffeine can stimulate the central nervous system and improve alertness.
   黃嘌呤類物質（如咖啡因）可以刺激中樞神經系統(tǒng)，增強警覺性。
2. The doctor advised against consuming too many products containing xanthines due to potential health risks.
   醫(yī)生建議避免過量攝入含有黃嘌呤類物質的產品，因為它們可能帶來健康風險。