Non-toxic isothiazolone-nitroxide hybrid compounds with enhanced antimicrobial and antibiofilm activity
Novel hybrid compounds combining isothiazolones with nitroxides to deliver potent antibacterial and antibiofilm effects against drug-resistant pathogens such as MRSA, VRSA, and Candida albicans, while significantly reducing human cytotoxicity compared to conventional isothiazolone biocides.
Overview
This solution introduces a new class of hybrid antimicrobial compounds formed by functionalizing isothiazolones with nitroxide groups. Conventional isothiazolones are widely used as industrial biocides but carry significant human cytotoxicity, limiting their applicability. By attaching nitroxide moieties, the resulting hybrids achieve stronger antibacterial and antibiofilm potency while eliminating cytotoxic effects in human cells. These compounds are positioned as next-generation active ingredients for antimicrobial formulations, particularly in cleaning products and surface disinfectants where both efficacy and safety are critical.
Technical specifications
Key features:
- Hybrid molecular design combining an isothiazolone core with a cyclic nitroxide group
- Demonstrated antibacterial potency against MRSA, MSSA, VRSA, and Enterococcus faecalis, with MIC values as low as 35 µM compared to 280 µM for the parent isothiazolone MIT
- Antibiofilm activity with MBEC of 280 µM, outperforming MIT which showed MBEC greater than 280 µM
- Additional undisclosed analogues show improved antimicrobial and antibiofilm activity over MIT in Staphylococcus aureus and Candida albicans
- No cytotoxicity observed in human epithelial T24 cells at concentrations up to 560 µM over 24 hours, while MIT showed significant cytotoxicity at concentrations as low as 35 µM
- Nitroxide functionalization expected to facilitate bacterial cell entry and reduce human toxicity
Technology readiness level
The technology is at an early-to-mid stage of development. Proof-of-concept validation has been completed in collaboration with Associate Professor Makrina Totsika, demonstrating both antimicrobial efficacy and reduced cytotoxicity in vitro. Additional related compounds have been synthesized and show promising preliminary results. The next phase of development requires synthesis optimization, scale-up, and evaluation in animal models. The research team is seeking a three-year partnership to advance the compounds toward commercial readiness, including broader pathogen testing and formulation development for applications such as all-purpose cleaners.
About Queensland University of Technology
Queensland University of Technology (QUT) is a major Australian public research university in Brisbane with two inner-city campuses and a practical, industry-focused culture. Industry partners tap shared core laboratories and technical staff through the Central Analytical Research Facility, and collaborate with QUT groups at the Translational Research Institute alongside hospital partners. A dedicated Office of Industry Engagement brokers collaborative and contract research, while entrepreneurship programs and commercialization pathways help convert university IP into ventures and licenses. Research is sustained by competitive national funding, including the Australian Research Council and National Health and Medical Research Council, with added support from programs such as the Medical Research Future Fund.
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