• Eswaran Ramachandran, Valentina Gandin, Roberta Bertani, Paolo Sgarbossa, Karuppannan Natarajan, Nattamai S P Bhuvanesh, Alfonso Venzo, Alfonso Zoleo, Mirto Mozzon, Alessandro Dolmella, Alberto Albinati, Carlo Castellano, Nuno Reis Conceição, M Fátima C Guedes da Silva, and Cristina Marzano.
• Department of Industrial Engineering, University of Padova, 35131 Padova, Italy.
• Molecules. 2020 Apr 17; 25 (8).

AbstractThree new 6-methyl-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-thiosemicarbazones-N-4-substituted pro-ligands and their Cu(II) complexes (1, -NH2; 2, -NHMe; 3, -NHEt) have been prepared and characterized. In both the X-ray structures of 1 and 3, two crystallographically independent complex molecules were found that differ either in the nature of weakly metal-binding species (water in 1a and nitrate in 1b) or in the co-ligand (water in 3a and methanol in 3b). Electron Paramagnetic Resonance (EPR) measurements carried out on complexes 1 and 3 confirmed the presence of such different species in the solution. The electrochemical behavior of the pro-ligands and of the complexes was investigated, as well as their biological activity. Complexes 2 and 3 exhibited a high cytotoxicity against human tumor cells and 3D spheroids derived from solid tumors, related to the high cellular uptake. Complexes 2 and 3 also showed a high selectivity towards cancerous cell lines with respect to non-cancerous cell lines and were able to circumvent cisplatin resistance. Via the Transmission Electron Microscopy (TEM) imaging technique, preliminary insights into the biological activity of copper complexes were obtained.

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