Synthesis and antiproliferative activity of thieno[2,3- d ]pyrimidine–pregnenolone selenocyanate hybrids

Using the bioisosterism principle and pharmacophore hybridization strategy, a series of structurally diverse pregnenolone selenocyanates bearing thieno[2,3-d]pyrimidine moieties were successfully synthesized and confirmed by nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HR-MS). Their in vitro antiproliferative activities against six human tumor cell lines was assessed via the MTT colorimetric assay. The results demonstrated that multiple hybrids containing the thieno[2,3-d]pyrimidine core exerted prominent growth-suppressive effects on tumor cells. Specifically, compounds 5b and 5h, which carry selenocyanate moieties linked through C5/C6 alkyl ester or amide, exhibited exceptional cytotoxicity toward HeLa and T47D cells, with IC50 values between 3.14 and 3.98 µmol/L. This work establishes a robust experimental basis and delivers rational molecular design guidance for the creation of new steroidal antiproliferative agents built around the thieno[2,3-d]pyrimidine skeleton.