Bioactivity of Decavanadate Compounds: Can Their In Vitro and In Vivo Effects Be Assessed in a Simple Manner?

Identifier:  imarina:9467121

Handle: https://hdl.handle.net/20.500.11797/imarina9467121

Authors:  Pessoa, JC; Zarroug, R; Ribeiro, N; Correia, I; Corte-Real, L; Ayed, B; Gomes, CSB; Marques, F; Masip-Sanchez, A; Hernandez-Carrasco, M; Lopez, X

Abstract:
Two decavanadate anions with 4-dimethylaminopyridinium and one with 1-methylimidazolium cations are isolated and characterized by single-crystal X-ray diffraction. The Hirshfeld surfaces and associated 2D-fingerprint plots confirm the propensity of V10 anions to undergo hydrogen-bonding interactions. DFT calculations demonstrate the tendency for protonation of decavanadates and, for the first time, the possibility of one or two-electron reduction maintaining the V10-cluster structure. Moreover, the tendency of V10 species to gain electrons increases with ion pairing, this effect depending on the counterion involved. The computed proton-coupled electron transfer energies indicate the prevalence of [HVV 9VIVO28]6-, [H2VV 8VIV 2O28]6-, or [H2VV 9VIVO28]5- species over V10. Decavanadates at total vanadium concentrations ([V]total) in the range 720-800 mu M undergo extensive hydrolysis within a few hours when added to RPMI cell incubation media. With the cell media in contact with A2780 ovarian cancer cells, V10 hydrolysis occurs much faster. Notably, the cytotoxicity and the vanadium uptake observed on A2780 cells for equal [V]total values are similar to solutions containing or not V10 anions, but preincubation with the VV solutions affect the biological activities, decreasing cell viability. These conclusions support the complexity of factors to be analyzed when discussing any biological effect observed, namely, protonation, redox processes, hydrolysis, ageing, counterions, and composition of the biological medium.