Syntheses, characterization, DNA/BSA binding, and in vitro cytostatic activity of fluorobenzenetelluronic triorganotin(iv) esters

Abstract

A new series of fluorobenzenetelluronic triorganotin(IV) esters, namely (R₃Sn)₄H₂L (H₆L¹ = [3-FC₆H₄TeO(OH)₃]₂, R = Me: 1, R = Ph: 2; H₆L² = [3,4-F₂C₆H₃TeO(OH)₃]₂, R = Me: 3, R = Ph: 4; H₆L³ = [3,4,5-F₃C₆H₂TeO(OH)₃]₂, R = Me: 5, R = Ph: 6), have been synthesized by the reaction of deprotonated fluorobenzenetelluronic acid ligands with the corresponding R₃SnCl (R = Me, Ph). All the complexes have been characterized by means of elemental analysis, FT-IR, NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy and X-ray crystallography. Structural analyses of the complexes reveal that they are isostructural and display an almost planar four-membered Te₂(μ₂-O)₂ core in the center. Each Te atom adopts a distorted octahedral geometry and each Sn atom adopts a distorted tetrahedral geometry. Complexes 1, 3, 5, and 6 form one-dimensional supramolecular structures, while 2 and 4 form two-dimensional supramolecular structures by intermolecular C–H⋯F or C–H⋯O interactions. Preliminary in vitro cytostatic studies show that these fluorobenzenetelluronic triorganotin esters exhibit effective cytostatic activity against a human cervical adenocarcinoma cell line (HeLa) and a human hepatocellular carcinoma cell line (HepG-2). For further discerning the apoptotic properties of cytostatic activity, the level of apoptosis was determined by flow cytometry (FACS assay). The DNA-binding properties of these complexes with calf thymus DNA (CT-DNA) and protein-binding properties with BSA were investigated by means of fluorescence titration. The results indicate that all the complexes could quench the intrinsic fluorescence of BSA in a static way.