Polyoxovanadate inhibition of Escherichia coli growth shows a reverse correlation with Ca2+-ATPase inhibition

Abstract

Recently, a global analysis of the structure–activity-relationship of a series of polyoxometalates (POMs) revealed that the most active POMs were ascribed to be polyoxovanadates (POVs), especially decavanadate (V₁₀), which was very active against certain bacteria (Bijelic et al., Chem. Commun., 2018). The present study explores this observation and compares the effects of three POVs namely MnV₁₁, MnV₁₃ and V₁₀ against Escherichia coli growth. It was observed that MnV₁₁ presents the lowest growth inhibition (GI₅₀) value for Escherichia coli followed by the MnV₁₃ compound, being about 2 times lower than that of V₁₀; respectively, the values obtained were 0.21, 0.27 and 0.58 mM. All three compounds were more effective than vanadate alone (GI₅₀ = 1.1 mM) and also than decaniobate, Nb₁₀ (GI₅₀ > 10 mM), an isostructural POM of V₁₀. However, the POVs exhibiting the highest antibacterial activity (MnV₁₁) were shown to have the lowest Ca²⁺-ATPase inhibitor capacity (IC₅₀ = 58 μM) whereas decavanadate, which was also very active against this membranar ATPase (IC₅₀ = 15 μM), was less active against bacterial growth, suggesting that POV inhibition of ion pumps might not be associated with the inhibition of Escherichia coli growth.