Assessment of the antimicrobial activity of new ciprofloxacin derivatives

Antibiotic resistance has been a known fact since the discovery of antibiotics, but in recent years, with the increase of resistant species and the decrease of effective and available antibiotics, it has become a worrying issue. Therefore, discovering or synthesizing new antibacterial agents plays a key role in solving the antibiotic resistance crisis. This study aimed to synthesize new derivatives of ciprofloxacin antibiotics to be more effective on ciprofloxacin-resistant bacteria.

A new series of thiourea and thiocarbamate derivatives of ciprofloxacin were synthesized and then the antibiogram test was performed by disk diffusion method on standard bacteria and clinically resistant bacteria. Also, the minimum inhibitory concentration and minimum bactericidal concentration of synthetic compounds were determined.

The results showed that all compounds S1-6 had antibacterial activity, and compound S4 was the most effective compound with an inhibition zone of 38 mm on P. aeruginosa ATCC 27853. The minimum inhibitory concentration of ciprofloxacin on E. coli ATCC 25922 is 50 μg/ml, while all the synthesized compounds have a minimum inhibitory concentration of less than 50 μg/ml, which indicates the high antibacterial activity of the synthetic compounds. In general, based on the obtained results, by adding different substituents and functional groups to ciprofloxacin, it is possible to synthesize new derivatives that are effective on resistant bacteria.