Synthesis, characterization and biological evaluation of some novel fluoroquinolones

Design, synthesis, and biological evaluation of pyrazole-ciprofloxacin hybrids as antibacterial and antibiofilm agents against Staphylococcus aureus

In our continued efforts to tackle antibiotic resistance, a new series of pyrazole-ciprofloxacin hybrids were designed, synthesized, and evaluated for their antibacterial activity against Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa), and Mycobacterium tuberculosis (Mtb). Most of the compounds exhibited good to excellent activities against S. aureus, and six compounds (7a, 7b, 7d, 7g, 7k, and 7p) exhibited higher or comparable activity (MIC = 0.125-0.5 μg mL-1) to ciprofloxacin (0.125 μg mL-1). Further, these selected compounds were non-toxic (CC50 ≥ 1000 μg mL-1) when evaluated for cell viability test against the Hep-G2 cell line. Three compounds (7a, 7d, and 7g) demonstrated excellent activity against ciprofloxacin-resistant S. aureus with MIC values ranging from 0.125-0.5 μg mL-1 and good antibiofilm activity. Among them, 7g displayed remarkable antibiofilm activity with an MBIC50 value of 0.02 μg mL-1, which is 50 times lower than ciprofloxacin (MBIC50 = 1.06 μg mL-1). A time-kill kinetics study indicated that 7g showed both concentration and time-dependent bactericidal properties. In addition, 7g effectively inhibited DNA-gyrase supercoiling activity at 1 μg mL-1 (8× MIC). Two compounds 7b and 7d exhibited the highest activity against Mtb with a MIC of 0.5 μg mL-1, while 7c showed the highest activity against P. aeruginosa with a MIC value of 2 μg mL-1. Molecular docking studies revealed that 7g formed stable interactions at the DNA active site.

An Overview of the Pharmacological Activities and Synthesis of Benzothiophene Derivatives

One important class of organic compounds having many uses, especially in medical chemistry, is benzothiophene and its derivatives. This review examines the biological activity of benzothiophene derivatives and summarizes the synthetic methods used in their production. The effectiveness of several synthetic pathways, such as cyclization techniques, functional group modifications, and reactions catalyzed by transition metals, in gaining access to benzothiophene scaffolds has been examined. Additionally, a broad spectrum of therapeutic domains, such as antiinflammatory, antibacterial, antidiabetic, anticancer, antimicrobial, anti-leishmanial, antifungal, antimalarial, and antitubercular activities, are covered by the pharmacological activities that are being explored. The synthesis and pharmacological potential of benzothiophene derivatives are well-explained in this thorough review, which opens up new options for medicinal chemistry and drug discovery study. Overall, this study is a useful resource for scientists working on drug development and discovery as it sheds light on the pharmacological potential of benzothiophene derivatives. This review includes the synthesis and bioactivities of the years 2002-2024. The goal of this review is to compile the existing information on benzothiophene derivatives and provide guidance for future research and development as well as insights into their possible medicinal uses.

The antibacterial potential of ciprofloxacin hybrids against Staphylococcus aureus

Staphylococcus aureus (S. aureus), an important pathogen of both humans and animals, is able to cause a variety of infections at any site of the body. The evolution of S. aureus resistance is notorious, and the widespread of drug-resistant S. aureus, especially methicillin-resistant S. aureus (MRSA), has made the treatment difficult in recent decades. Nowadays, S. aureus is among the leading causes of bacterial infections, creating an urgent need for the development of novel antibacterial agents. Ciprofloxacin, characterized by high clinical efficacy, is a broad-spectrum antibacterial agent with frequency of prescription for various Gram-positive and Gram-negative pathogens, many of which are resistant to a wide range of antibiotics. However, the long-term and widespread use of this antibiotic has led to the emergence of ciprofloxacin-resistant pathogens, and ciprofloxacin-resistant S. aureus has been noted in clinical practice. Ciprofloxacin hybrids have been recognized as advanced chemical entities to simultaneously modulate multiple drug targets in bacteria, so ciprofloxacin hybrids have the potential to overcome drug resistance. The present review provides an overview of ciprofloxacin hybrids with anti-S. aureus potential that have been reported in the last decade with emphasis on their structure-activity relationships and mechanisms of action.

Design, Synthesis, and Antibacterial Screening of Some Novel Heteroaryl-Based Ciprofloxacin Derivatives as DNA Gyrase and Topoisomerase IV Inhibitors

A novel series of ciprofloxacin hybrids comprising various heterocycle derivatives has been synthesized and structurally elucidated using ¹H NMR, ¹³C NMR, and elementary analyses. Using ciprofloxacin as a reference, compounds 1-21 were screened in vitro against Gram-positive bacterial strains such as Staphylococcus aureus and Bacillus subtilis and Gram-negative strains such as Escherichia coli and Pseudomonas aeruginosa. As a result, many of the compounds examined had antibacterial activity equivalent to ciprofloxacin against test bacteria. Compounds 2-6, oxadiazole derivatives, were found to have antibacterial activity that was 88 to 120% that of ciprofloxacin against Gram-positive and Gram-negative bacteria. The findings showed that none of the compounds tested had antifungal activity against Aspergillus flavus, but did have poor activity against Candida albicans, ranging from 23% to 33% of fluconazole, with compound 3 being the most active (33% of fluconazole). The most potent compounds, 3, 4, 5, and 6, displayed an IC₅₀ of 86, 42, 92, and 180 nM against E. coli DNA gyrase, respectively (novobiocin, IC₅₀ = 170 nM). Compounds 4, 5, and 6 showed IC₅₀ values (1.47, 6.80, and 8.92 µM, respectively) against E. coli topo IV in comparison to novobiocin (IC₅₀ = 11 µM).

The use of magnetic starch as a support for an ionic liquid-β-cyclodextrin based catalyst for the synthesis of imidazothiadiazolamine derivatives

In this paper, a novel catalyst is introduced based on the introduction of an ionic liquid onto the β-cyclodextrin. The ionic liquid-β-cyclodextrin was anchored to magnetic starch (denoted βCD-IL@M-Starch) and fully characterized by several methods including TEM, TGA, VSM and FT-IR. The catalyst was used for the synthesis of imidazo[2,1-b][1,3,4]thiadiazol-5-amine and imidazo[1,2-a]pyridin-3-amine derivatives. βCD-IL@M-Starch catalyst showed very good activity in the synthesis of diphenylimidazo[2,1-b][1,3,4]thiadiazol-5-amine derivatives from the corresponding benzaldehyde, semicarbazide, benzaldehydes and isocyanides. The products were obtained in a mild reaction conditions in good isolated yields in the presence of βCD-IL@M-Starch as catalyst. The catalyst showed to be magnetically reusable, and gave very good results in 10 sequential reactions.

Ciprofloxacin derivatives and their antibacterial activities

Bacterial infections represent a significant health threat globally, and are responsible for the majority of hospital-acquired infections, leading to extensive mortality and burden on global healthcare systems. The second generation fluoroquinolone ciprofloxacin which exhibits excellent antimicrobial activity and pharmacokinetic properties as well as few side effects is introduced into clinical practice for the treatment of various bacterial infections for around 3 decades. The emergency and widely spread of drug-resistant pathogens making ciprofloxacin more and more ineffective, so it's imperative to develop novel antibacterials. Numerous of ciprofloxacin derivatives have been synthesized for seeking for new antibacterials, and some of them exhibited promising potency. This review aims to summarize the recent advances made towards the discovery of ciprofloxacin derivatives as antibacterial agents and the structure-activity relationship of these derivatives was also discussed.

4-Quinolone derivatives and their activities against Gram positive pathogens

Gram-positive bacteria are responsible for a broad range of infectious diseases, and the emergency and wide spread of drug-resistant Gram-positive pathogens including MRSA and MRSE has caused great concern throughout the world. 4-Quinolones which are exemplified by fluoroquinolones are mainstays of chemotherapy against various bacterial infections including Gram-positive pathogen infections, and their value and role in the treatment of bacterial infections continues to expand. However, the resistance of Gram-positive organisms to 4-quinolones develops rapidly and spreads widely, making them more and more ineffective. To overcome the resistance and reduce the toxicity, numerous of 4-quinolone derivatives were synthesized and screened for their in vitro and in vivo activities against Gram-positive pathogens, and some of them exhibited excellent potency. This review aims to outlines the recent advances made towards the discovery of 4-quinolone-based derivatives as anti-Gram-positive pathogens agents and the critical aspects of design as well as the structure-activity relationship of these derivatives. The enriched SAR paves the way to the further rational development of 4-quinolones with a unique mechanism of action different from that of the currently used drugs to overcome the resistance, well-tolerated and low toxic profiles.