The swift spread of infections caused by drug-resistant bacteria, such as methicillin-resistant Staphylococcus aureus (MRSA), has quickly become a worldwide concern as infections spread from healthcare settings to the wider community. While ferrocenyl chalcones, which are chalcone derivatives with antimicrobial activity, have gained attention from researchers, further study is needed to assess their cytotoxicity. Ten newly developed chalcones, in which ring A was replaced with a ferrocenyl moiety and ring B contained increasing alkyl chain lengths from 5-10 carbons, were assessed. Using 2-fold broth microdilution, the minimum inhibitory concentration (MIC) of five of the ten compounds were lower against Gram-positive organisms (MICs from 0.008 mg/ml to 0.063 mg/ml) than Gram-negative organisms (MICs = 0.125 mg/ml). These novel ferrocenyl chalcone compounds were effective against 3 types of clinically isolated drug-resistant S. aureus, including a MRSA, and against other non-resistant clinically isolated and laboratory-adapted Gram-positive bacteria. The same compounds inhibited growth in non-resistant bacteria by potentially obstructing cellular respiration in Gram-positive bacteria. Images obtained through scanning electron microscopy revealed fully lysed bacterial cells once exposed to a selected compound that showed activity. The results indicate that these newly developed compounds could be important antimicrobial agents in the treatment of infections from clinically resistant bacteria.

Increased infection spread is partly facilitated by reduced new drug development. Because of their antimicrobial properties, ferrocenyl chalcone derivatives were assessed in a previous study. However, dilutions of stock ferrocenyl chalcone solution with Mueller-Hinton broth (MHB) resulted in particle formation, and a colour change from deep red to dark-brown. Results of the current study con rmed particle formation, which suggested the chelation of casein hydrolysate, a component of MHB, by iron ion. After solubilisation in dimethyl sulfoxide (DMSO), each of the iodine-containing compounds, also changed from deep red to dark-brown. Mean rates of colour change (RA) in polypropylene tubes at 37 o C were the highest (0.0102 ± 0.0005 ΔA/min -0.0041 ± 0.0009 ΔA/min) while the same observed reaction in borosilicate glass tubes 21 o C ± 1 were the lowest (0.0024 ± 0.0007 ΔA/min -0.0021 ± 0.0003 ΔA/min). Antimicrobial activity of two randomly selected ferrocenyl chalcone compounds (hexyl and heptyl) was unaffected after colour change occurred (0.016 mg/ml -0.125 mg/ml). Although these ndings potentially indicate that short-term storage of antimicrobials is unaffected, further work is required to assess whether antimicrobial activity is affected by longer storage conditions.

The spread of healthcare-associated infections has become a matter of global concern. These infections, which were once isolated to hospital settings, have emerged in the community. Reduced infection control practices are a major cause of this rapid spread of infections, which has led to the increase in the occurrence of multi-drug resistant organisms. The state of infection control in the United Kingdom is of extreme importance because of several reported cases of infections caused by these organisms. In addition to antimicrobial usage in human medicine, antimicrobial agents used in agriculture must be considered as major factors in the prevalence of resistant organisms and the implications to the UK. However, this increased occurrence of antimicrobial resistant bacteria and their resulting infections could be reduced with the application of effective policies for antibiotic use in agricultural environments, stringent decontamination and sterilisation techniques and better regulations that encourage the search for, and development of, new and novel drugs.

Increased infection spread is partly facilitated by reduced new drug development. Because of their antimicrobial properties, ferrocenyl chalcone derivatives were assessed in a previous study. However, dilutions of stock ferrocenyl chalcone solution with Mueller-Hinton broth (MHB) resulted in particle formation, and a colour change from deep red to dark-brown. Results of the current study confirmed particle formation, which suggested the chelation of casein hydrolysate, a component of MHB, by iron ion. After solubilisation in dimethyl sulfoxide (DMSO), each of the iodine-containing compounds, also changed from deep red to dark-brown. Mean rates of colour change (RA) in polypropylene tubes at 37oC were the highest (0.0102 ± 0.0005 ΔA/min – 0.0041 ± 0.0009 ΔA/min) while the same observed reaction in borosilicate glass tubes 21oC ± 1 were the lowest (0.0024 ± 0.0007 ΔA/min – 0.0021 ± 0.0003 ΔA/min). Antimicrobial activity of two randomly selected ferrocenyl chalcone compounds (hexyl and heptyl) was unaffected after colour change occurred (0.016 mg/ml – 0.125 mg/ml). Although these findings potentially indicate that short-term storage of antimicrobials is unaffected, further work is required to assess whether antimicrobial activity is affected by longer storage conditions.