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Item Polyoxovanadate inhibition of: Escherichia coli growth shows a reverse correlation with Ca2+-ATPase inhibition(Royal Society of Chemistry, 2019) Marques-Da-Silva, D.; Fraqueza, G.; Lagoa, R.; Anandan Vannathan, A.A.; Mal, S.S.; Aureliano, M.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 ?M) whereas decavanadate, which was also very active against this membranar ATPase (IC50 = 15 ?M), was less active against bacterial growth, suggesting that POV inhibition of ion pumps might not be associated with the inhibition of Escherichia coli growth. This journal is © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.Item Inhibition of Na + /K + - and Ca 2+ -ATPase activities by phosphotetradecavanadate(Elsevier Inc. usjcs@elsevier.com, 2019) Fraqueza, G.; Fuentes, J.; Krivosudský, L.; Dutta, S.; Mal, S.S.; Roller, A.; Giester, G.; Rompel, A.; Aureliano, M.Polyoxometalates (POMs)are promising inorganic inhibitors for P-type ATPases. The experimental models used to study the effects of POMs on these ATPases are usually in vitro models using vesicles from several membrane sources. Very recently, some polyoxotungstates, such as the Dawson anion [P 2 W 18 O 62 ] 6? , were shown to be potent P-type ATPase inhibitors; being active in vitro as well as in ex-vivo. In the present study we broaden the spectrum of highly active inhibitors of Na + /K + -ATPase from basal membrane of epithelial skin to the bi-capped Keggin-type anion phosphotetradecavanadate Cs 5.6 H 3.4 PV 14 O 42 (PV 14 )and we confront the data with activity of other commonly encountered polyoxovanadates, decavanadate (V 10 )and monovanadate (V 1 ). The X-ray crystal structure of PV 14 was solved and contains two trans-bicapped ?-Keggin anions H x PV 14 O 42 (9-x)- . The anion is built up from the classical Keggin structure [(PO 4 )@(V 12 O 36 )]capped by two [VO]units. PV 14 (10 ?M)exhibited higher ex-vivo inhibitory effect on Na + /K + -ATPase (78%)than was observed at the same concentrations of V 10 (66%)or V 1 (33%). Moreover, PV 14 is also a potent in vitro inhibitor of the Ca 2+ -ATPase activity (IC 50 5 ?M)exhibiting stronger inhibition than the previously reported activities for V 10 (15 ?M)and V 1 (80 ?M). Putting it all together, when compared both P-typye ATPases it is suggested that PV 14 exibited a high potential to act as an in vivo inhibitor of the Na + /K + -ATPase associated with chloride secretion. © 2019 The Authors