Synthesis and cytotoxic activity of dibutyltin complexes derived from pyridoxamine and salicylaldehydes

Abstract

The synthesis of monomeric pentacoordinated diorganotin complexes derived from pyridoxamine dihydrochloride and substituted salicylaldehydes is described. The complexes were characterized using UV/Vis, IR, MS, as well as 1 H, 13 C, and 119 Sn NMR techniques; the molecular structure of the 1e complex was established by X-ray diffraction, which showed a distorted trigonal bipyramidal geometry, in which the basal plane is defined by the butyl groups and the azomethine nitrogen atom, whereas the oxygen atoms from the aromatic ring occupy axial positions. The cytotoxic activity of the complexes against human cell lines U-251 (glioblastoma), PC-3 (prostate), K-562 (chronic myelogenous leukemia), HCT-15 (human colorectal), MCF-7 (human breast), SKLU-1 (non-small cell lung), and MDA-MB-251 (human breast) was evaluated, and the inhibitory percentage values indicated higher activities than the reference standard, cisplatin, and non-cytotoxic activity was observed in culture of mononuclear cells from peripheral blood on healthy Wistar rats. Oral toxicity studies were performed by the OECD test guide line 423 and reveals that LD 50 of complexes 1a, 1b, 1c-1g is in the range of 200-300 mg/Kg body weight and can be classified under category 3, the complexes 1c and 1h resulted to be the less toxic.

Tin(IV) Schiff base complexes derived from pyridoxal: Synthesis, spectroscopic properties and cytotoxicity

“…The spectra also revealed a singlet in the range 9.17 to 9.53 ppm, due to the azomethine HC═N proton with a 3 J ( 119 Sn, 1 H) coupling constant value in the range 36–55 Hz, which supports the involvement of the azomethine nitrogen in the formation of N─Sn coordination bonds between nitrogen and tin atoms; this is a clear indication that the nitrogen atom remains coordinated to the metal in solution. These values are in agreement with those reported for butyltin complexes obtained from pyridoxamine, confirming the presence of N─Sn coordination in all complexes.…”

“…The electronic spectra of all complexes showed two bands, 206–209 nm ( ε max = 48 920–24 664 M −1 cm −1 ) and 227–311 nm ( ε max = 10 925–4729 M −1 cm −1 ), for the aromatic ring (π–π*) charge transfer transitions. The azomethine C═N group absorbed in the ranges 305–348 and 457–470 nm, which could be due to the π–π* and n–π* transitions of the chromophore (C═N), respectively; this is in agreement with those transitions described previously for pyridoxamine derivatives . Additionally, sharp bands were observed in the range 226–283 nm which may be due to charge transfer and dπ–pπ bonds between oxygen and nitrogen of ligands and vacant 5d orbitals of tin…”

“…Involvement of nitrogen and oxygen or sulfur in coordination was supported by the appearance of new bands in the regions 404–491 and 479–562 cm −1 assigned to ν (Sn─N) and ν (Sn─O) modes; the band at 562 cm −1 in the spectrum of 3k could be attributed to ν (Sn─S). Bands at 537–692 cm −1 were assigned to ν (Sn─C), as was observed for piridoxamine derivatives . In the IR spectra of all the tin complexes of pyridoxal‐substituted imines, the ν (C═N) band appeared at 1580–1597 cm −1 , confirming coordination through azomethine nitrogen to the diorganotin(IV) moiety.…”

“…Complex 3k showed a different chemical shift, −127 in CDCl 3 and −177 ppm in DMSO‐ d 6 , that could probably be affected by the presence of sulfur as the donor in the ligand. For phenyltin complexes 4a – 4c , the chemical shifts showed values from −324 to −328 ppm (CDCl 3 ) and −432 to −436 ppm (DMSO‐ d 6 ), a characteristic range for pentacoordinate and hexacoordinate diphenyltin(IV) compounds, respectively …”

Schiff pentadentate ligands based on an [ON 2 O 2 ] core displaying structural isomerism and their coordination to dibutyltin moieties

“…Tin compounds containing ligands based on mono-and bisaldimines [1] are of interest because of their photophysical properties [2], activity in catalysis [3], and biological properties [4]. Most of these compounds have ligands with [NO] [5,6,7,8].…”