5-Chloro-2 -deoxyuridine (CAS No 50-90-8) is a nucleoside analog commonly used in biomedical research especially in studies related to DNA synthesis and repair mechanisms Originating from modified pyrimidine derivatives it incorporates into DNA and interferes with replication leading to the inhibition of cellular proliferation Its mechanism of action involves targeting the DNA polymerase pathways making it effective in various experimental models In vitro it exhibits activity in the nanomolar to low micromolar range This compound is frequently employed in cancer research particularly in cell culture models and animal studies to assess its potential as a chemotherapeutic agent It s also used in drug screening assays to evaluate novel drug interactions and efficacy Experimental concentrations typically depend on the specific research design allowing flexibility for researchers to tailor their studies according to their unique objectives and model systems