Synthesis and anticancer potential of novel 5,6-oxygenated and/or halogenated steroidal D-homo lactones

A series of 5,6-modified steroidal D-homo lactones, comprising of halogenated and/or oxygenated derivatives, was synthesized and evaluated for potential anticancer properties. Preparation of many of these compounds involved investigating alternative synthetic pathways. In silico ADME testing was performed for both novel and some previously synthesized compounds. Calculated physicochemical properties were in accordance with the Lipinski, Veber, Egan, Ghose and Muegge criteria, suggesting the potential of these molecules as orally active agents. Cytotoxicity of the synthesized steroid derivatives was tested on six tumor and one normal human cell line. None of the investigated derivatives was toxic to non-cancerous MRC-5 control cells. Most of the compounds showed significant cytotoxicity against the treated cancer cell lines. Most notably, the 3 beta,5 alpha,6 beta-trihydroxy derivative exhibited strong cytotoxicity against multiple cell lines (MCF-7, MDA-MB-231 and HT-29), with the highest effect observed for lung adenocarcinoma (A549) cells, for which this steroid was more cytotoxic than all of the three commercial chemotherapeutic agents used as reference compounds. Molecular docking suggests the 3 beta,5 alpha,6 beta-trihydroxy derivative could bind the EGFR tyrosine kinase domain with high affinity, providing a potential mechanism for its cytotoxicity via inhibition of EGFR signaling. The most active compounds were further studied for their potential to induce apoptosis by the double-staining fluorescence method; where the 5 alpha,6 beta dibromide, 5 alpha,6 beta-dichloride and 3 beta,5 alpha,6 beta-triol induced apoptotic changes in all three treated cell lines: MDAMB-231, HT-29 and A549. To predict interactions with nuclear steroidal receptors, affinity for the ligand binding domains of ER alpha, ER beta and AR was measured using a yeast-based fluorescence assay. The 5 beta,6 beta-epoxide, dibromide and 5 alpha-hydroxy-3,6-dioxo derivatives showed affinity for ER alpha, while the 5 alpha-fluoro-6 beta-hydroxy and 3 beta-acetoxy-5 alpha,6 beta-dihydroxy derivatives were identified as ER beta ligands. None of the tested compounds showed affinity for AR. Structure-activity relationships of selected compounds were also examined.

Automated summary

A series of 5,6-modified steroidal D-homo lactones, including halogenated and/or oxygenated derivatives, were synthesized and evaluated for potential anticancer properties. The synthesized compounds showed significant cytotoxicity against cancer cell lines, with a 3 beta,5 alpha,6 beta-trihydroxy derivative exhibiting strong cytotoxicity against multiple cell lines. Molecular docking suggested a potential mechanism for cytotoxicity through inhibition of EGFR signaling. Some compounds were found to induce apoptosis in treated cell lines and exhibit affinity for estrogen receptors.