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

A set of mononuclear ruthenium complexes, i.e. [Ru(Dg)(C6H6)Cl-2] (<bold>RuBDg</bold>), [Ru(Dg)((p-cymene)Cl-2] (<bold>RuCDg</bold>) were synthesized using a phytosteroid diosgenin (<bold>Dg</bold>) 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(center dot+), DPPH center dot, O2-, NO center dot 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. <bold>RuCDg</bold> exhibited potent ability to kill A549 and HeLa cancer cells with IC50 values of 5.8 +/- 0.5 mu M and 5.5 +/- 0.6 mu M, respectively. Similarly, <bold>RuBDg</bold> showed activity towards A549 and HeLa cancer cells with IC50 values of 16 +/- 1 mu M and 12 +/- 1 mu M, respectively. These values are better than that of free diosgenin (A549 - 48 +/- 2 mu M and HeLa - 43 +/- 1 mu M). 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.