Synthesis, Anticancer Screening, and In Silico Evaluations of Thieno[2,3- c]pyridine Derivatives as Hsp90 Inhibitors

Thieno[2,3-c]pyridines and their analogs are not well explored for their anticancer properties. Hence, our research aimed to establish the anticancer potential of thieno[2,3-c]pyridines through cell-based assays and in silico evaluations.

The compound 6i induced cell death via mechanisms that are different from apoptosis. Thus, the synthesized thieno[2,3-c]pyridine derivatives can be suitable lead compounds to be optimized to obtain potent anticancer agents through Hsp90 inhibition.

Thieno[2,3-c]pyridine derivatives 6(a-k) were synthesized and characterized using FT-IR, 1H-NMR, 13C-NMR, and HRMS. All the synthesized compounds were screened initially for their anticancer activity against MCF7 and T47D (breast cancer), HSC3 (head and neck cancer), and RKO (colorectal cancer) cell lines using MTT assay. Apoptosis and cell cycle analyses were conducted using Annexin V/propidium iodide (PI) double staining for apoptosis assessment and PI staining for cell cycle analysis to investigate the mechanisms underlying the reduced cell viability. In silico molecular docking was accomplished for the synthesized compounds against the Hsp90 and determined pharmacokinetics properties.

From the screening assay, compounds 6a and 6i were identified as potential inhibitors and were further subjected to IC50 determination. The compound 6i showed potent inhibition against HSC3 (IC50 = 10.8 µM), T47D (IC50 = 11.7 µM), and RKO (IC50 = 12.4 µM) cell lines, all of which indicated a broad spectrum of anticancer activity. Notably, 6i was found to induce G2 phase arrest, thereby inhibiting cell cycle progression. Molecular docking results indicated crucial molecular interactions of the synthesized ligands against the target Hsp90.