Novel Hydrazono-2-Iminothiazolidin-4-Ones Based on a Monoterpenic Skeleton as Potential Antitumor Agents: Synthesis, DFT Studies, in Vitro Cytotoxicity, Apoptosis Inducing Properties and Molecular Docking

A series of novel 2-iminothiazolidin-4-one analogs have been synthesized from limonaketone, and structurally characterized by HR-MS, H-1-NMR and C-13-NMR spectroscopy techniques, and the structure of compound 4 was elucidated by XRD. The newly synthesized products were biologically evaluated in vitro for their cytotoxic activity against human cancer cell lines HT-1080, A549, and MCF-7. Thiazolidinones 9 and 10 were the most active compounds in HT-1080 cell lines (IC50=15.85 +/- 1.75 and 16.13 +/- 1.55 mu M, respectively). The apoptosis induction of the derivatives 9 and 10 were studied using annexin V staining, caspase-3/7 activity and cell cycle analysis. Compound 10 showed the highest ability of apoptosis induction and caspase-3/7 activation associated with S-phase growth arrest in HT-1080. Meanwhile, compound 9 has a moderate apoptotic effect and G0/G1-phase arrest in the after-mentioned cell. The molecular docking suggested that compounds 9 and 10 formed stable ligand-caspase-3 complexes. Besides, the presence of phenyl moiety in ligand 10 is responsible for the enhancement of the caspase-3 activation by the apparition of two additional hydrogen bonds with Cys163 and Gln161amino acids.