5'-deoxy-5-Fluorocytidine

5'-deoxy-5-Fluorocytidine (CAS No.: 66335-38-4) is a cytidine analog and key intermediate metabolite in the biotransformation of the prodrug capecitabine, widely studied in the context of antimetabolite-based cancer therapeutics and epigenetic regulation. Formed in the liver via carboxylesterase-mediated conversion of capecitabine, this compound undergoes sequential enzymatic deamination by cytidine deaminase to yield 5'-deoxy-5-fluorouridine, which is further converted by thymidine phosphorylase in tumor tissues to the active cytotoxic agent 5-fluorouracil, thereby contributing to selective antitumor activity. Mechanistically, as a nucleoside analog, it can be incorporated into nucleic acids and is associated with disruption of DNA synthesis and modification processes, while also being implicated in interference with DNA methyltransferase activity and modulation of DNA methylation pathways. Its biological effects are primarily indirect, with cytotoxicity arising after metabolic activation, and activity is typically observed in the nanomolar to micromolar range depending on cellular context and enzymatic expression profiles. 5'-deoxy-5-Fluorocytidine is commonly utilized in biochemical and pharmacological studies investigating fluoropyrimidine metabolism, tumor-selective drug activation, and epigenetic regulation, as well as in in vitro cell-based assays and in vivo tumor models of colorectal, breast, and non-small cell lung cancers, where experimental concentrations and dosing regimens vary according to specific study designs and objectives.