Synergistic Antiproliferative Activity of Newly Synthesized Benzimidazole-Based Silver(I) Complexes on MCF-7 and T47D Cell Lines, CT-DNA Interactions Supported by Computational Studies

This article reports the synthesis, characterization, and antitumor properties of newly synthesized benzimidazole-based Ag(I)-(BNHCs) complexes from their proligands. All of the compounds underwent comprehensive characterization using techniques such as ¹H, COSY, ¹³C NMR, IR spectroscopy, electrospray ionization (ESI)-mass, elemental, and single-crystal X-ray diffraction (XRD) analysis. Density functional theory (DFT) studies were carried out to observe the electronic effects of bound ligands to modulate the selectivity and reactivity of silver complexes. Time-dependent DFT (TD-DFT) studies assessed the optical properties of synthesized complexes and were further highlighted by orbital contributions with oscillator strengths. All compounds were tested against breast cancer MCF-7 and T47D cell lines. The synergistic effects of benzimidazole-incorporated aryl constituent structuring silver complexes were also observed. Nearly all silver complexes have been found to be promising anticancer agents with the added benefit of low cytotoxic effects toward normal cells. Intriguingly, <b>[AgL</b> ^<b>4</b> <b>(Cl)]</b> exhibited the best cytotoxic activity among our screened complexes as IC₅₀ values for both MCF-7 and T47D were 9 ± 1.04 and 11 ± 1.41, respectively. The apoptosis mode of cell death was confirmed by phosphatidylserine exposure and annexin V/PI staining imaging method. CT-DNA interactions of the most active silver complex (<b>[AgL</b> ^<b>4</b> <b>(Cl)]</b>) and its proligand (<b>HL</b> ^<b>4</b> <b>(Cl)</b>) were carried out to support the mode of compound-DNA interaction. Strong DNA binding affinities (<i>K</i> _b) with compounds through electrostatic and intercalation modes induced structural changes in DNA. Moreover, molecular docking studies were carried out to comprehend the possible interactions of compounds with various receptors such as EGFR (epidermal growth factor receptor), VEGFR2 (vascular endothelial growth factor receptors), FGFR (fibroblast growth factor receptor), and SRC (proto-oncogene tyrosine kinase protein) of tyrosine kinase family serves as crucial receptors in breast cancer.