Author: Krzysztof M. Borys

Antifungal activity and tautomeric cyclization equilibria of formylphenylboronic acids

2-Formylphenylboronic acid and four isomeric fluoro-2-formylphenylboronic acids have been found active against a series of fungal strains: Aspergillus, Fusarium, Penicillium and Candida. The level of antifungal activity was evaluated by agar diffusion tests as well as the determination of minimum inhibitory concentrations (MICs) by serial dilution method. Among the tested compounds, 4-fluoro-2-formylphenylboronic acid - an analogue of the known antifungal drug Tavaborole (AN2690) - proved to be the most potent antifungal agent. The tautomeric equilibrium leading to the formation of 3-hydroxybenzoxaboroles as well as the position of the fluorine substituent were revealed to play a crucial ro…

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Mechanochemical synthesis of antifungal bis(benzoxaboroles)

Several piperazine bis(benzoxaboroles) have been obtained both in solution as well as in the solid state. The environmentally friendly mechanochemical approach – hitherto not applied for the preparation of benzoxaboroles – was particularly beneficial in the case of two products afforded in low yields in solution. The in vitro studies showed high potential of the studied bis(fluorobenzoxaboroles) as antifungal agents, highlighting also the influence of the fluorine substituent position on their microbiological activity. The highest activity against A. niger, A. terreus, P. ochrochloron, C. tenuis and C. albicans was displayed by the analogue of the known benzoxaborole antifungal drug Kerydin…

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Investigation of fungicidal activity of 3-piperazine-bis(benzoxaborole) and its boronic acid analogue

3-Piperazine-bis(benzoxaborole) and its bis(phenylboronic acid) analogue were investigated in terms of their fungicidal activity. The study was carried out against five filamentous fungi: Aspergillus terreus, Fusarium dimerum, Fusarium solani, Penicillium ochrochloron and Aspergillus niger. 3-Piperazine-bis(benzoxaborole) revealed higher inhibitory activity towards the examined strains than standard antibiotic (amphotericin B), whereas bis(phenylboronic acid) proved to be inactive. The study unequivocally showed that the presence of the heterocyclic benzoxaborole system is essential for antifungal action of the examined compounds. Copyright © 2014 John Wiley & Sons, Ltd.

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Synthesis and structural elucidation of novel antifungal N-(fluorophenyl)piperazinyl benzoxaboroles and their analogues

Abstract Series of novel N-(fluorophenyl)piperazine derivatives of phenylboronic compounds including benzoxaboroles, phenylboronic acids and phenylboronic methyl monoester have been obtained by facile synthetic methods starting from 2-formylphenylboronic acid. Molecular and crystal structures of those novel derivatives have been investigated by single crystal X-ray diffraction method. The Bond Valence Vector Model was used to describe strains in the boron coordination sphere. Microbiological activity of novel benzoxaboroles as well as their corresponding acid analogues against: A. niger, A. terreus, P. ochrochloron, C. tenuis and F. dimerum has been evaluated. The presence of heterocyclic b…

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