Synthesis and Antimicrobial Activities of Boron-Containing Isoniazid Derivatives

A series of boron-containing imines derived from isoniazid were prepared and characterized by multi-nuclear NMR and FT-IR spectroscopies as well as elemental analysis. An X-ray diffraction study was performed on the bis-pyridyl derivative, revealing that the imine exists as the E-isomer in the solid state. Potential antibacterial properties were studied against five bacteria strains, including the Gram-negative species Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa as well as the Gram-positive Methicillin-resistant Staphylococcus aureus (MRSA). Antifungal testing of all compounds was performed on two yeasts, Candida albicans and Cryptococcus neoformans var. grubii. While poor antifungal and antibacterial activities were observed in most cases, appreciable antibacterial activity against MRSA was observed for several compounds while the thiophene-containing derivative displayed significant activity.