Organotin (IV) complexes from Schiff bases ligands based on 2-amino-3-hydroxypyridine: synthesis, characterization, and cytotoxicity

A multicomponent reaction was used as a synthetic strategy to prepare organotin (IV) complexes, 2-amino-3-hydroxypyridine, saliciladehydes 5-R-substituted (H, CH3, OCH3, C(CH)3, F, Cl, Br, I, NO2), and dibutyltin(IV) oxide were used as starting materials. The complexes were analyzed by IR, UV–Visible, MS, NMR of 1H, 13C, 119Sn. The complex 3a was structurally identified by X-ray crystallography, which revealed a dimeric arrangement where the tin atom possess a distorted hexacoordinated environment in which the deprotonated phenolic oxygen atoms and the nitrogen atom of the azomethine from the ligand are coordinated to the metallic center, and one of the phenoxy oxygens bridges with the tin through an intermolecular interaction forming a planar Sn2O2 core. As strategy of molecular design, isosteric and bioisosteric replacement of halogens were employed. All organotin compounds were assessed for their in vitro cytotoxic activity on cancer cell lines K‐562 (chronic myelogenous leukemia), U‐251 (glioblastoma), HCT‐15 (human colorectal cancer), MCF‐7, MDA-MB-231 (human breast cancer), and SKLU‐1 (non‐small‐cell lung cancer). They evidenced an elevated cytotoxic activity, and the inhibitory percentage values stated higher activity than the cis-platin. The K-562 and MDA-MB-231 cells were more sensitive to organotin (IV) complexes than HCT-15 and MCF-7. The organotin (IV) compounds were also tested in vivo for brine shrimp lethality to examine their toxic properties.