Stability in solution and chemoprotection by octadecavanadates(IV/V) in E. coli cultures

Kahoana Postal, Francielli S. Santana, David L. Hughes, André L. Rüdiger, Ronny R. Ribeiro, Eduardo L. Sá, Emanuel M. De Souza, Jaísa F. Soares, Giovana G. Nunes

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Two mixed-valence octadecavanadates, (NH 4) 2(Me 4N) 5[V IV 12V V 6O 42I]·Me 4NI·5H 2O (V 18I) and [{K 6(OH 2) 12V IV 11V V 7O 41(PO 4)·4H 2O} n] (V 18P), were synthesized and characterized by single-crystal X-ray diffraction analysis and FTIR, Raman, 51V NMR, EPR and UV/Vis/NIR spectroscopies. The chemoprotective activity of V 18I and V 18P towards the alkylating agent diethyl sulfate was assessed in E. coli cultures. The complex V 18I was nontoxic in concentrations up to 5.0 mmol L −1, while V 18P presented moderate toxicity in the concentration range 0.10 - 10 mmol L −1. Conversely, a ca. 35% enhancement in culture growth as compared to cells treated only with diethyl sulfate was observed upon addition of V 18I (0.10 to 2.5 mmol L −1), while the combination of diethyl sulfate with V 18P increased the cytotoxicity presented by diethyl sulfate alone. 51V NMR and EPR speciation studies showed that V 18I is stable in solution, while V 18P suffers partial breakage to give low nuclearity oxidometalates of vanadium(V) and (IV). According to the results, the chemoprotective effect depends strongly on the direct reactivity of the polyoxidovanadates (POV) towards the alkylating agent. The reaction of diethyl sulfate with V 18I apparently produces a new, rearranged POV instead of poorly-reactive breakage products, while V 18P shows the formation and subsequent consumption of low-nuclearity species. The correlation of this chemistry with that of other mixed-valence polyoxidovanadates, [H 6V IV 2V V 12O 38PO 4] 5- (V 14) and [V IV 8V V 7O 36Cl] 6- (V 15), suggests a relationship between stability in solution and chemoprotective performance.

Original languageEnglish
Article number111438
JournalJournal of Inorganic Biochemistry
Early online date26 Mar 2021
Publication statusPublished - Jun 2021


  • Alkylation
  • Chemoprotection
  • Diethyl sulfate
  • Polyoxidovanadates
  • Speciation

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