Xanthine: This compound is present in substances like theobromine and theophylline and is found in tea and colas. Chemically, xanthine is classified as a purine. A rare disorder called xanthinuria arises from a deficiency in the enzyme xanthine dehydrogenase, which is essential for metabolizing xanthine in the body. If not properly managed, xanthinuria can result in the formation of xanthine stones, leading to kidney disease, and can also cause muscle disease due to xanthine deposits in the muscles. Management involves avoiding foods and beverages that contain xanthine derivatives, such as coffee, tea, and colas. The term "xanthine" is derived from the Greek word "xanqos," meaning yellow, because it forms yellow salts and its solution exhibits a blue fluorescence similar to that of quinine.