The antibacterial activity of polyoxometalates: structures, antibiotic effects and future perspectives

Polyoxometalates (POMs) are, mostly anionic, metal oxide compounds that span a wide range of tunable physical and chemical features rendering them very interesting for biological purposes, an continuously emerging but little explored field. Due to their biological and biochemical effects, including antitumor, -viral and -bacterial properties, POMs and POM-based systems are considered as promising future metallodrugs. In this article, we focus on the antibacterial activity of POMs and their therapeutic potential in the battle against bacteria and their increasing resistance against pharmaceuticals. Recent advances in the synthesis of POMs are highlighted, with emphasis on the development and properties of biologically active POM-based hybrid and nanocomposite structures. By analysing the antibacterial activity and structure of POMs, putative mode of actions are provided, including potential targets for POM–protein interactions, and a structure–activity-relationship was established for a series of POMs against two bacteria, namely Helicobacter pylori and Streptococcus pneumoniae.info:eu-repo/semantics/publishedVersio

Hofmeister effect in the Keggin-type polyoxotungstate series

International audienceThe chaotropic character of Keggin-type polyoxotungstate anions was evaluated with respect to their ability to bind to γ-cyclodextrin (γ-CD) by varying the global charge density of the nanometer-sized polyanion. The strengths of the host-guest association were analyzed within the series of isostructural [XW12O40] n-anions where ionic charge varies from 6-to 3-depending on the heteroatom, respectively, X = H2 2+ , B 3+ , Si 4+ or P 5+. Titration experiments using complementary techniques (ITC, DOSY NMR, and electrochemistry) revealed that the affinity between γ-CD and the polyoxometalate (POM) is directly correlated to the charge density of the Keggin anion as reflected in the values of the binding constants K1:1. These constants increase dramatically following the order: [H2W12O40] 6- 10 5 M-1), but also the ability to interact with both CD faces resulting in a wide variety of supramolecular aggregates