Among all modern antibiotics, fluoroquinolones are well known for their broad spectrums of activity and efficiency toward microorganisms and viruses. However, antibiotic resistance is still a problem, which has encouraged medicinal chemists to modify the initial structures in order to combat resistant strains. Our current work is aimed at synthesizing novel hybrid derivatives of ciprofloxacin and norfloxacin and applying docking studies and biological activity evaluations in order to find active promising molecules. We succeeded in the development of a synthetic method towards 1,2,3-triazole-substituted ciprofloxacin and norfloxacin derivatives. The structure and purity of the obtained compounds were confirmed by 1H NMR, 13C NMR, 19F NMR, LC/MS, UV-, IR- spectroscopy. Docking studies, together with in vitro research against Staphylococcus aureus ATCC 25923, Escherichia coli ATCC 25922, Bacillus subtilis ATCC 6633, Pseudomonas aeruginosa ATCC 27853, Candida albicans NCTC 885-653 revealed compounds in which activity exceeded the initial molecules.

The aim of the work. Among all the representatives of four generations of fluoroquinolones ciprofloxacin (CIPRO) and norfloxacin (NOR) remain widely used and prescribed antibiotics in clinical practice. However, the problem of resistance towards them is gradually increasing. Thus, our investigation is dedicated to chemical modification of C-7 position of Ciprofloxacin and Norfloxacin ring as a promising solution to combat antibiotic resistance and open a pathway towards convenient synthesis of new fluoroquinolones derivatives. Materials and methods. The subjects of the research were N-piperazine-substituted ciprofloxacin and norfloxacin. The methods of molecular docking and organic synthesis were applied in the study. The structures of the obtained compounds were confirmed by 1H NMR, 13C NMR, 19F NMR, LC/MS, IR, UV spectroscopy. The antimicrobial activity was measured by the method of double serial dilutions against Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Bacillus subtilis (ATCC 6633), Pseudomonas aeruginosa (ATCC 27853), Candida albicans (NCTC 885-653) and diffusion in agar method against clinical strains. The results. 7-(4-(2-Cyanoacetyl)piperazin-1-yl)-1-R-6-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylic acids were synthesized and their structures were confirmed. The obtained compounds showed the antibacterial activity on the reference level for double dilution method and exceeded control for “well” method. Conclusions. The current investigation revealed the promising route for the expanding of the existing fluoroquinolones diversity. Pharmacodynamics and pharmacokinetics changes could be achieved by chemical modifications of C-7 position of the initial ring. Further research utilizing the obtained compounds as starting ones opens a promising way to novel active molecules synthesis and combating the problem of antibiotic resistance

The title compound, C24H26N2O4S, can be obtained via two synthetic routes. According to our investigations, the most suitable way is by the reaction of ethyl 2-bromoacetate with sodium tosylsulfinate in dry DMF. It was crystallized from methanol into the monoclinic P21/n space group with a single molecule in the asymmetric unit. Hirshfeld surface analysis was performed to define the hydrogen bonds and analysis of the two-dimensional fingerprint plots was used to distinguish the different types of interactions. Two very weak non-classical C—H...O hydrogen bonds were found and the contributions of short contacts to the Hirshfeld surface were determined. Molecules form an isotropic network of intermolecular interactions according to an analysis of the pairwise interaction energies. A molecular docking study evaluated the interactions in the title compound with the active centers of macromolecules of bacterial targets (Staphylococcus aureus DNA Gyrase PDB ID: 2XCR, Mycobacterium tuberculosis topoisomerase II PDB ID: 5BTL, Streptococcus pneumoniae topoisomerase IV PDB ID: 4KPF) and revealed high affinity towards them that exceeded the reference antibiotics of the fluoroquinolone group.

Fluoroquinolones have been studied for more than half a century. Since the 1960s, four generations of these synthetic antibiotics have been created and successfully introduced into clinical practice. However, they are still of interest for medicinal chemistry due to the wide possibilities for chemical modification, with subsequent useful changes in the pharmacokinetics and pharmacodynamics of the initial molecules. This review summarizes the chemical and pharmacological results of fluoroquinolones hybridization by introducing different heterocyclic moieties into position 3 of the core system. It analyses the synthetic procedures and approaches to the formation of heterocycles from the fluoroquinolone carboxyl group and reveals the most convenient ways for such procedures. Further, the results of biological activity investigations for the obtained hybrid pharmacophore systems are presented. The latter revealed numerous promising molecules that can be further studied to overcome the problem of resistance to antibiotics, to find novel anticancer agents and more.

Aim. To analyze the available literature data on the methods of synthesis, chemical transformations and the biological activity of derivatives containing a sultone core – 1,2-benzoxathiin-4(3H)-one 2,2-dioxide – and to show the possibilities of their further use in the construction of new molecular systems with attractive pharmacological properties. Results and discussion. The most widespread method for the synthesis of 1,2-benzoxathiin-4(3H)-one 2,2-dioxides is the cyclization of salicylic acid derivatives. The known chemical transformations of 1,2-benzoxathiin-4(3H)-one 2,2-dioxides deal with all reaction centers of the heterocyclic fragment of the condensed system – C=O and CH2 groups, SO2–O bond, CH2CO fragment as a whole. It should be noted that the oxathiine nucleus is prone to undergo recyclizations. The use of 1,2-benzoxathiin-4(3H)-one 2,2-dioxides in multicomponent transformations still remains hardly explored. The “abnormal” course of some classical transformations involving 1,2-benzoxathiine 2,2-dioxides is also noteworthy. The study of the pharmacological properties of 1,2-benzoxathiin-4(3H)-one 2,2-dioxide derivatives is scarce and mainly based on their structural similarity to the coumarin core, which led to the study of anticoagulant, antimicrobial and antitumor properties for the sultone derivatives. Conclusions. The analysis has shown a limited number of studies in each aspect – approaches to the synthesis of 1,2-benzoxathiin-4(3H)-one 2,2-dioxides, their chemical transformations and the study of their pharmacological activity. In addition to a small number of publications on this heterocyclic system, there have been almost no sultone studies in the last 20 years. Taking this into account 1,2-benzoxathiin-4(3H)-one 2,2-dioxide and its derivatives deserve close attention as objects of research for experimental chemistry and pharmacology.