Abstract
Novel vitamin E chelate siderophore derivatives and their VV and FeIII complexes have been synthesised and the chemical and biological properties have been evaluated. In particular, the α- and δ-tocopherol derivatives with bis-methyldroxylamino triazine (α-tocTHMA) and (δ-tocDPA) as well their VV complexes, [V2VO3(α-tocTHMA)2] and [V2IVO3(δ-tocTHMA)2], have been synthesised and characterised by infrared (IR), nuclear magnetic resonance (NMR), electron paramagnetic resonance (EPR) and ultra violet-visible (UV-Vis) spectroscopies. The dimeric vanadium complexes in solution are in equilibrium with their respefrctive monomers, H2O + [V2VO2(μ-O)]4+ = 2 [VVO(OH)]2+. The two amphiphilic vanadium complexes exhibit enhanced hydrolytic stability. EPR shows that the complexes in lipophilic matrix are mild radical initiators. Evaluation of their biological activity shows that the compounds do not exhibit any significant cytotoxicity to cells.
Highlights
Some of the features of these amphiphilic replaced with the triazine moiety forming an inert ether bond and, the new organic molecules will act as ligand owing lower antioxidant activity than free tocopherols; the formation of the tocopheryl radical requires deprotonation of chromanol group
The complexes were characterised by elemental analysis, UV-vis, IR and nuclear magnetic resonance (NMR) spectroscopies
The ability of the new vanadium compounds to produce radicals was examined by monitoring the generation of α-tocopheryl radicals in olive oil by cw X-band electron paramagnetic resonance (EPR) using 2D
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Vanadium compounds exert antitumor effects through activation of apoptotic pathways, cell cycle arrest and the generation of Reactive Oxygen Species (ROS), inducing lower toxicity than anticancer platinum-based molecules [4,20,21,22,23,24,25]. The ligands in this study are β-tocopherol molecules substituted with chelate groups in o-position derivatives (Scheme 1, H3 β-tocDEA), enabling coordination of the metal ion from the phenolic oxygen. Some of the features of these amphiphilic replaced with the triazine moiety forming an inert ether bond and, the new organic molecules will act as ligand owing lower antioxidant activity than free tocopherols; the formation of the tocopheryl radical requires deprotonation of chromanol group. As chelate group for VV we have chosen of the siderophore hydroxylamino-triazine (Scheme 1), targeting to enhance the hydrolytic stability of the VV complexes as much as possible.
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