A novel 1D borotungstate polymer: Structure and biologic activity

In this study, a novel boron-containing polyoxometalate (BPOM) coordination polymer, Na5[trea]3[BW12O40]& sdot; 3H2O (Compound 1; trea = triethylamine), with a molecular weight of 3329.57 g/mol, was synthesized and comprehensively characterized by elemental analysis, single-crystal X-ray diffraction, NMR and FT-IR spectroscopy. Antimicrobial assays demonstrated that Compound 1 exhibited MIC values ranging from 62.5-1000 mu g/mL (1.88x10-5-3.00x10-4 M) for Gram-positive strains and 3.9-62.5 mu g/mL (1.17x10-6-1.88x10-5 M) for Gram-negative strains. The strongest inhibition was observed against Arcobacter butzleri AB5 with a MIC of 3.9 mu g/mL (1.17x10-6 M) and MBC of 7.18 mu g/mL (2.15x10-6 M). For Staphylococcus aureus ATCC 29213, MIC and MBC were 62.5 mu g/mL (1.88x10-5 M) and 250 mu g/mL (7.51x10-5 M), respectively. For Listeria monocytogenes, MIC values were 250-1000 mu g/mL (7.51x10-5-3.00x10-4 M). Antibiofilm testing using a virulent Escherichia coli wild-type strain revealed a concentration-dependent inhibition, with 72% biofilm reduction at 1000 mu g/mL (3.00x10-4 M) and 60%, 56%, 48%, 37%, and 21% reduction at 500, 250, 125, 62.5 and 31.2 mu g/mL, respectively. Haemolysis assays showed 0% erythrocyte lysis up to 1000 mu g/mL, indicating non-toxic behavior toward red blood cells. DNA interaction experiments using pBR322 plasmid DNA demonstrated no conversion of supercoiled Form Ito nicked (Form II) or linear DNA (Form III) at 1000 mu g/mL (3.00x10-4 M) or 500 mu g/mL (1.50x10-4 M) after 4 h incubation at 37 degrees C, indicating absence of DNA cleavage activity. These data position boron-substituted polyoxometalates as promising antimicrobial and antibiofilm candidates with clearly defined quantitative performance parameters.