The syntheses and characterizations of vanadium complexes with 1,2-dihydroxyanthraquinone and the structure–effect relationship in their in vitro anticancer activities

Abstract

[V^VO₂(O₂C₁₄H₆O₂)(C₅N₂H₁₂)](C₅N₂H₁₃)(CH₃OH) (1) and {Na[V^VO(O₂C₁₄H₆O₂)₂][(CH₃)₂NCHO]}_n (2) have been synthesized by the reaction of V₂O₅ and NaVO₃ with aromatic 1,2-diol (1,2-dihydroxyanthraquinone), and their molecular and crystal structures have been determined by X-ray diffraction. MTT assay tests of the V^VO₂L_AL_B and V^VOL₂ complexes against cancer cells have revealed that, when L is catechol, VOL₂ showed broad-spectrum, high anticancer activities which were proportional to their concentration; however when L is naphthol or alizarin, VOL₂ displayed little effect towards the cancer cells; moreover, complex 1 in the coordination model of V^VO₂L_AL_B showed specifically higher inhibition (88.65%) against HCT-8 than the clinical anticancer drug Fu-5 (69.97%). The results revealed that both the V(V) and the ligands cannot influence the inhibition against cancer cells individually. The mechanism of the broad-spectrum anticancer activities of VOL₂ when L is catechol ligand might originate from the redox activities of V^V/V^IV which regulate the concentration of ROS (reactive oxygen species). N-Methylpiperazine formed as a by-product in complex 1 was confirmed by ¹H NMR and its formation mechanism catalyzed by V₂O₅ has been deduced.