Daunorubicin hydrochloride (Rubidomycin hydrochloride) is an anthracycline aminoglycoside, a topoisomerase II (Topo II) inhibitor. Daunorubicin hydrochloride inhibits DNA and RNA synthesis and has antitumor activity.

DNA synthesis:20 nM (Ki), DNA biosynthesis:10 µM (human skin fibroblasts), collagen biosynthesis:70 µM (human skin fibroblasts), prolidase:10 µM (human skin fibroblasts)

Daunorubicin (Dnr) is prepared in PBS[2]. The chemosensitivity to Daunorubicin is assessed using the MTT assay. In brief, the 96 well plates are set up with cells at the initial density of 2×105 cells/mL and are incubated at 37°C for 72 h in an atmosphere of 5% CO2 in the absence and presence of nine different concentrations of Daunorubicin (Dnr) or Dox ranging from 1.90 to 0.007 μM in triplicate. After incubation, 10 μL of MTT solution (5 mg/mL tetrazolium salt) is added to each well and the plates are incubated for a further 4 h at 37°C. The formazan salt crystals are dissolved by adding 100 μL 10% SDS in 10 mM HCl solution and incubating over night at 37°C. The absorbance is measured at 540 nm with a reference at 650 nm by a 96-well enzyme-linked immunosorbent assay (ELISA) plate reader. Chemosensitivity is expressed as the IC50, which is the concentration of drug causing 50% cell survival compare to control cells grown without drug. Calculations are carried out using Microsoft Excel[2].