Biological evaluation of ruthenium(II) complexes appended curcumin derivatives: Synthesis, spectral characterization, anti-oxidant and anti-cancer studies

A series of biologically active Ru(II) arene complexes containing curcumin based Schiff bases were synthesized and characterized by various spectral (IR, UV-Vis, NMR and ESI-MS) and analytical techniques. On the basis of spectral studies, the formation of the compounds was confirmed and the ligands coordinated with the Ru(II) ion via bidentate manner through their azomethine nitrogen and anionic nitrogen (N,N - ) atoms to give 1:1 (M:L) stoichiometry in ruthenium complexes. Free radical scavenging ability of the synthesized ligands and Ru(II) complexes were analyzed towards different radicals like ABTS center dot+ , DPPH center dot , O 2- , NO center dot and OH - and the obtained results indicated that the compounds possessed significant efficacy compared to ascorbic acid. Further, anticancer study of the compounds was undertaken with A549 (Lung Cancer cells) and HeLa (Cervical Cancer cells) cells using MTT assay and activity of the complexes exceeded that of their parent ligands and the standard drug cisplatin . The IC 50 values of the compounds were greater than 200 mu M for non-cancerous HUVEC cells (human umbilical vein endothelial cells) indicating their specificity towards cancer cells. Further, the apoptogenic nature of the compounds was confirmed by using AO-EB staining assay.