Novel ferrocenyl chalcone derivatives as antibacterial agents: is there a solution to the problem?

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 37 °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 °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 (0.016−0.125 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.