Synthesis, spectral characterization and biological evaluation of diosgenin coordinated ruthenium-arene complexes

Abstract

A set of mononuclear ruthenium complexes, i.e. [Ru(Dg)(C₆H₆)Cl₂] (RuBDg), [Ru(Dg)((p-cymene)Cl₂] (RuCDg) were synthesized using a phytosteroid diosgenin (Dg) as ligand. The formulations and characterizations of the complexes were achieved through elemental analyses, infrared, electronic absorption, electron paramagnetic resonances, mass spectrometric analysis, and molar conductance studies. Ruthenium ion is octahedrally coordinated to the oxygen of diosgenin, one arene moiety and two chlorides. An assessment of the antioxidant activities of the compounds indicated better scavenging ability against ABTS^•+, DPPH^•, O²⁻, NO^• and OH⁻ radicals. The metal complexes showed activity towards free radicals compared to the parent diosgenin. The anticancer activities of diosgenin and the ruthenium complexes were evaluated by MTT assay against the human lung cancer cell line (A549) and cervical carcinoma cell line (HeLa), with cisplatin as a reference. RuCDg exhibited potent ability to kill A549 and HeLa cancer cells with IC₅₀ values of 5.8 ± 0.5 µM and 5.5 ± 0.6 µM, respectively. Similarly, RuBDg showed activity towards A549 and HeLa cancer cells with IC₅₀ values of 16 ± 1 µM and 12 ± 1 µM, respectively. These values are better than that of free diosgenin (A549 − 48 ± 2 µM and HeLa − 43 ± 1 µM). The morphological changes of the HeLa and A549 cells with the complexes, studied by AO-EB and DAPI staining methods, suggested cell death through apoptosis.

Keywords:

• Anticancer activity
• antioxidant activity
• diosgenin
• Ru(III) arene complexes
• spectral characterization

Acknowledgements

G.K. greatly acknowledges Tamil Nadu State Council for Science and Technology for providing Young Scientist Fellowship Scheme project fellowship (TNSCST/YSFS/VR/19/2021-2022). S.P. gratefully acknowledges DST for providing the Women Scientist Scheme - WOS (A) fellowship, Department of Science and Technology, New Delhi, India [Grant No. SR/WOS(A)/CS-147/2021]. This work is also funded by Researcher supporting project number (RSPD2024R680), King Saud University, Riyadh, Saudi Arabia.

Disclosure statement

The authors declare no competing financial interest.