Steroidal pyrimidines: Synthesis, characterization, molecular docking studies with DNA and in vitro cytotoxicity

A series of new steroid pyrimidines (7–9) were synthesized by reacting steroidal thiosemicarbazones (4–6) with diethyl malonate. The new compounds were characterized by IR, 1H NMR, 13C NMR, MS and analytical data. The interaction studies of compounds (7–9) with DNA were carried out by employing gel electrophoresis, UV–vis and fluorescence spectroscopy. The acting force between the compounds (7–9) and DNA was mainly hydrophobic while the other interactions like van der Waals, hydrogen bonding cannot be ruled out. The gel electrophoresis pattern also demonstrated that the compound 7 alone or in presence of Cu (II) causes the nicking of supercoiled pBR322 and it seems to follow the mechanistic pathway involving generation of hydroxyl radicals that are responsible for initiating DNA strand scission. The docking study of compounds (7–9) suggested that the intercalation of compounds in between the nucleotide base pairs might be due to the presence of pyrimidine moiety in steroid molecule. MTT assay was carried out to check the toxicity of new compounds (7–9) against the different human cancer as well as non-cancer cell lines A545, MCF-7, HeLa, HL-60, SW480, HepG2, HT-29, A549, 184B5, MCF10A, NL-20, HPC and HPLF. Apoptotic degradation of DNA in presence of steroidal pyrimidines (7–9) was analyzed by agarose gel electrophoresis and visualized by ethidium bromide staining (comet assay).