Evaluation of antimicrobial activity of halogenated boroxine dipotassium trioxohydroxytetrafluorotriborate K2[B3O3F4OH]

The present study investigated the antimicrobial potential of a halogenated boroxine dipotassium trioxohydroxytetrafluorotriborate ; K2 [B3O3F4OH] (boroxine) targeting opportunistic pathogens associated with skin and wound infections in humans. The antimicrobial testing against eleven bacterial and four fungal species revealed good activity of boroxine against pathogenic filamentous fungi Penicillium funiculosum and Aspergillus niger (MIC50 64 and 128 µg/ml, respectively), and a moderate bioactivity against the yeast Candida albicans (MIC50 512 µg/ml). The best boroxine antibacterial effect, stable over a 24-h period, was observed against the methicillin-resistant Staphylococcus aureus strain (MRSA) with MIC50 =1024 µg/ml. Atomic force microscopy (AFM) was used to investigated the morphology of S. aureus cells and colonies after the exposure to boroxine. The boroxine showed effect on S. aureus cell envelope as indentation of cell wall studied by AFM. Membrane permeability assay proved that cytotoxic effect of boroxine on S. aureus was not result of membrane disintegration.