Novel silver complexes bearing trans-cinnamaldehyde-derived thiosemicarbazones: synthesis, characterization, and effects against tumour cell lines

Abstract

Cancer represents a public health problem as well as an economic burden. Considering that cell resistance and side effects have limited the clinical use of anticancer platinum(II)-based chemotherapeutics, silver(I) compounds have appeared as potential candidates due to their multi-target mode of action and low toxicity in healthy cell lines. In this work, we report the synthesis, characterization and biological evaluation of new silver complexes [Ag(R-cTSC)(phen)]NO₃·H₂O, R-cTSC = trans-cinnamaldehyde-N(4)-R-thiosemicarbazone (R = H (C1), methyl (C2), ethyl (C3), phenyl (C4)) and phen = 1,10-phenanthroline. Silver complexes C1-C4 were tested against some tumour cell lines, with IC₅₀ values varying in the range of 1.6–4.4 µM (A2780cis), 5.4–23.3 µM (A549), and 6.5–15.9 µM (MCF-7). Results from cytotoxic evaluation and colony formation assay data indicated that C3 exerted a good effect towards A2780cis (3.8 ± 0.3 µM), A549 (5.5 ± 0.1 µM) and MCF-7 (8.1 ± 0.7 µM) and displayed both cytotoxic and cytostatic effects against A2780cis cells at 1.1 µM. DNA binding studies showed that C3 was able to release part of bound Hoechst 33258 from the minor groove and inhibited topoisomerase-IIα catalytic activity at low concentration (> 1 µM). Additionally, in silico studies suggested interaction between the 1,10-phen moiety and topoisomerase-IIα Lys157 and Arg98 amino acid residues.