Cytidine derivatives are chemical compounds that are structurally related to cytidine, a nucleoside composed of a cytosine base and a ribose sugar. These derivatives can include modifications to the base, sugar, or both, which can affect their biological activity and stability. They play important roles in cellular processes, including RNA synthesis and metabolism. These compounds are often studied for their potential therapeutic applications, particularly in treating viral infections and certain types of cancer. Some cytidine derivatives, like azacitidine, are used in clinical settings to modify gene expression and inhibit tumor growth, showcasing their significance in modern medicine.