Design and synthesis of ciprofloxacin-sulfonamide hybrids to manipulate ciprofloxacin pharmacological qualities: Potency and side effects

Synthesis and antibacterial medicinal evaluation of carbothioamido hydrazonyl thiazolylquinolone with multitargeting antimicrobial potential to combat increasingly global resistance

The global microbial resistance is a serious threat to human health, and multitargeting compounds are considered to be promising to combat microbial resistance. In this work, a series of new thiazolylquinolones with multitargeting antimicrobial potential were developed through multi-step reactions using triethoxymethane and substituted anilines as start materials. Their structures were confirmed by 1H NMR, 13C NMR and HRMS spectra. Antimicrobial evaluation revealed that some of the target compounds could effectively inhibit microbial growth. Especially, carbothioamido hydrazonyl aminothiazolyl quinolone 8a showed strong inhibitory activity toward drug-resistant Staphylococcus aureus with MIC value of 0.0047 mM, which was 5-fold more active than that of norfloxacin. The highly active compound 8a exhibited negligible hemolysis, no significant toxicity in vitro and in vivo, low drug resistance, as well as rapidly bactericidal effects, which suggested its favorable druggability. Furthermore, compound 8a was able to effectively disrupt the integrity of the bacterial membrane, intercalate into DNA and inhibit the activity of topoisomerase IV, suggesting multitargeting mechanism of action. Compound 8a could form hydrogen bonds and hydrophobic interactions with DNA-topoisomerase IV complex, indicating the insertion of aminothiazolyl moiety was beneficial to improve antibacterial efficiency. These findings indicated that the active carbothioamido hydrazonyl aminothiazolyl quinolone 8a as a chemical therapeutic candidate demonstrated immense potential to tackle drug-resistant bacterial infections.

Advancements in Synthetic Strategies and Biological Effects of Ciprofloxacin Derivatives: A Review

Ciprofloxacin is a widely used antibiotic in the fluoroquinolone class. It is widely acknowledged by various researchers worldwide, and it has been documented to have a broad range of other pharmacological activities, such as anticancer, antiviral, antimalarial activities, etc. Researchers have been exploring the synthesis of ciprofloxacin derivatives with enhanced biological activities or tailored capability to target specific pathogens. The various biological activities of some of the most potent and promising ciprofloxacin derivatives, as well as the synthetic strategies used to develop them, are thoroughly reviewed in this paper. Modification of ciprofloxacin via 4-oxo-3-carboxylic acid resulted in derivatives with reduced efficacy against bacterial strains. Hybrid molecules containing ciprofloxacin scaffolds displayed promising biological effects. The current review paper provides reported findings on the development of novel ciprofloxacin-based molecules with enhanced potency and intended therapeutic activities which will be of great interest to medicinal chemists.

Discovery of Dehydroabietylamine Derivatives as Antibacterial and Antifungal Agents

A diverse array of biologically active derivatives was derived by modifying the chemically active sites of dehydroabietylamine. Herein, we describe the synthesis of a new series of C-19-arylated dehydroabietylamine derivatives using a palladium-catalyzed C(sp3)-H activation reaction. Five analogues (3b, 3d, 3h, 3n, and 4a) exhibited antibacterial activity against Escherichia coli. Compound 4a exhibited strong inhibitory activity against DNA Topo II and Topo IV. Molecular docking modeling indicated that it can bind effectively to the target through interactions with amino acid residues. The synthesized compounds were tested in vitro for their antifungal activity against six common phytopathogenic fungi. The mechanism of action of compound 4c against Rhizoctorzia solani was investigated, revealing that it disrupts the morphology of the mycelium and enhances cell membrane permeability.

Design, synthesis, biological evaluation and docking analysis of pyrrolidine-benzenesulfonamides as carbonic anhydrase or acetylcholinesterase inhibitors and antimicrobial agents

The synthesis and biological assessment of novel multi-functionalized pyrrolidine-containing benzenesulfonamides were reported along with their antimicrobial, antifungal, CAs inhibition, and AChE inhibition as well as DNA-binding effects. The chemical structure of the compounds was elucidated by using FTIR, NMR, and HRMS. Compound 3b, which had Ki values of 17.61 ± 3.58 nM (hCA I) and 5.14 ± 0.61 nM (hCA II), was found the be the most potent CAs inhibitor. Compounds 6a and 6b showed remarkable AChE inhibition effects with Ki values 22.34 ± 4.53 nM and 27.21 ± 3.96 nM in comparison to tacrine. Compounds 6a-6c had moderate antituberculosis effect on M. tuberculosis with a MIC value of 15.62 μg/ml. Compounds had weaker antifungal and antibacterial activity in the range of MIC 500-62.5 μg/ml against standard bacterial and fungal strains. Besides these above, molecular docking studies were performed to examine and evaluate the interaction of the remarkable compounds (3b, 6a and 6b) against the current enzymes (CAs and AChE). Novel compounds gained interest in terms of enzyme inhibitory potencies. Therefore, the most potent enzyme inhibitors may be considered lead compounds to be modified for further research.Communicated by Ramaswamy H. Sarma.

A ternary nucleotide-lanthanide coordination nanoprobe for ratiometric fluorescence detection of ciprofloxacin

Ciprofloxacin (CIP) is a widely used broad-spectrum antibiotic and has been associated with various side effects, making its accurate detection crucial for patient safety, drug quality compliance, and environmental and food safety. This study presents the development of a ternary nucleotide-lanthanide coordination nanoprobe, GMP-Tb-BDC (GMP: guanosine 5'-monophosphate, BDC: 2-amino-1,4-benzenedicarboxylic acid), for the sensitive and ratiometric detection of CIP. The GMP-Tb-BDC nanoprobe was constructed by incorporating the blue-emissive ligand BDC into the Tb/GMP coordination polymers. Upon the addition of CIP, the fluorescence of terbium ion (Tb3+ ) was significantly enhanced due to the coordination and fluorescence sensitization properties of CIP, while the emission of the BDC ligand remained unchanged. The nanoprobe demonstrated good linearity in the concentration range of 0-10 μM CIP. By leveraging mobile phone software to analyze the color signals, rapid on-site analysis of CIP was achieved. Furthermore, the nanoprobe exhibited accurate analysis of CIP in actual drug and milk samples. This study showcases the potential of the GMP-Tb-BDC nanoprobe for practical applications in CIP detection.

Structure-based drug discovery and antimicrobial activity of ciprofloxacin-grafted Ugi adducts

A new series of ciprofloxacin-derived Ugi adducts were rationally designed and synthesized. The synthesized molecules were explored for their potential antimicrobial activities against four pathogenic microorganisms. Among these derivatives, compound 7h with a 4-nitrophenyl substituent at R2 exhibited significant activity against two tested Gram-positive bacteria with a minimum inhibitory concentration value of 0.097 µg/mL while 7i bearing 4-chlorophenyl pendant demonstrated the best antimicrobial activities against Gram-negative bacteria. Furthermore, the analysis of the structure-activity relationships disclosed that types of substitutions differently affect the bacteria so the most potent derivative against Gram-negative infections was the least active one in Gram-positive microorganisms. Also, the molecular docking and molecular dynamic simulations were executed on 7i as the most potent Gram-negative anti-bacterial agent against ATP-binding sites of DNA gyrase B. Accordingly, our findings suggest that ciprofloxacin-based Ugi adducts are an interesting precursor for the design of potent antimicrobial agents.Communicated by Ramaswamy H. Sarma.

Introducing of novel class of pyrano[2,3-c]pyrazole-5-carbonitrile analogs with potent antimicrobial activity, DNA gyrase inhibition, and prominent pharmacokinetic and CNS toxicity profiles supported by molecular dynamic simulation

Microbiological DNA gyrase is recognized as an exceptional microbial target for the innovative development of low-resistant and more effective antimicrobial drugs. Hence, we introduced a one-pot facile synthesis of a novel pyranopyrazole scaffold bearing different functionalities; substituted aryl ring, nitrile, and hydroxyl groups. All new analogs were characterized with full spectroscopic data. The antimicrobial screening for all analogs was assessed against standard strains of Gm + ve and Gm-ve through in vitro considers. The screened compounds displayed very promising MIC/MBC values against some of the bacterial strains with broad or selective antibacterial effects. Of these, 4j biphenyl analog showed 0.5-2/2-8 µg/mL MIC/MBC for suppression and killing of Gm + ve and Gm-ve strains. Moreover, the antimicrobial screening was assessed for the most potent analogs against certain highly resistant microbial strains. Consequently, DNA gyrase supercoiling assay was done for all analogs using ciprofloxacin as reference positive control. Obviously, the results showed a different activity profile with potent analog 4j with IC50 value 6.29 µg/mL better than reference drug 10.2 µg/mL. Additionally, CNS toxicity testing was done using the HiB5 cell line for attenuation of GABA/NMDA expression to both 4j and ciprofloxacin compounds that revealed better neurotransmitter modulation by novel scaffold. Importantly, docking and dynamic simulations were performed for the most active 4j analog to investigate its interaction with DNA binding sites, which supported the in vitro observations and compound stability with binding pocket. Finally, a novel scaffold pyranopyrazole was introduced as a DNA gyrase inhibitor with prominent antibacterial efficacy and low CNS side effect toxicity better than quinolones.Communicated by Ramaswamy H. Sarma.

Investigation of the phytochemical composition, antioxidant, antibacterial, anti-osteoarthritis, and wound healing activities of selected vegetable waste

Agri-food wastes, produced following industrial food processing, are mostly discarded, leading to environmental hazards and losing the nutritional and medicinal values associated with their bioactive constituents. In this study, we performed a comprehensive analytical and biological evaluation of selected vegetable by-products (potato, onion, and garlic peels). The phytochemical analysis included UHPLC-ESI-qTOF-MS/MS in combination with molecular networking and determination of the total flavonoid and phenolic contents. Further, the antimicrobial, anti-osteoarthritis and wound healing potentials were also evaluated. In total, 47 compounds were identified, belonging to phenolic acids, flavonoids, saponins, and alkaloids as representative chemical classes. Onion peel extract (OPE) showed the higher polyphenolic contents, the promising antioxidant activity, the potential anti-osteoarthritis activity, and promising antimicrobial activity, especially against methicillin-resistant Staphylococcus aureus (MRSA). Furthermore, OPE revealed to have promising in vivo wound healing activity, restoring tissue physiology and integrity, mainly through the activation of AP-1 signaling pathway. Lastly, when OPE was loaded with nanocapsule based hydrogel, the nano-formulation revealed enhanced cellular viability. The affinities of the OPE major metabolites were evaluated against both p65 and ATF-2 targets using two different molecular docking processes revealing quercetin-3,4'-O-diglucoside, alliospiroside C, and alliospiroside D as the most promising entities with superior binding scores. These results demonstrate that vegetable by-products, particularly, those derived from onion peels can be incorporated as natural by-product for future evaluation against wounds and osteoarthritis.

Dual promoted ciprofloxacin degradation by Fe0/PS system with ascorbic acid and pre-magnetization

As a widely used and hard-to-degrade pharmaceuticals and personal care product (PPCP), ciprofloxacin (CIP) was frequently found in water environment and the detected concentration was gradually increased. Although zero-valent iron (ZVI) has been shown to be effective in destroying refractory organic pollutants, the practical application and sustained catalytic performance is not satisfactory. Herein, introduction of ascorbic acid (AA) and employment of pre-magnetized Fe⁰ was achieved to maintain a high-concentration of Fe²⁺ during persulfate (PS) activation. Pre-Fe⁰/PS/AA system presented the best performance for CIP degradation, achieving almost complete elimination of 5 mg/L CIP within 40 min in the reaction conditions of 0.2 g/L pre-Fe⁰，0.05 mM AA and 0.2 mM PS. The CIP degradation retarded as excess pre-Fe⁰ and AA were added, therefore, the optimum dosages of pre-Fe⁰ and AA were determined to be 0.2 g/L and 0.05 mM, respectively. The CIP degradation gradually decreased as the initial pH increased from 3.05 to 11.03. The presence of Cl^-, HCO₃^-, Al³⁺, Cu²⁺ and humic acid significantly influenced the performance of CIP removal, while Zn²⁺, Mg²⁺, Mn²⁺, and NO₃^- slightly affected the CIP degradation. Combined with the results of HPLC analysis and previous literature, several possible degradation pathways of CIP were proposed.

Controlling the Evolution of Selective Vancomycin Resistance through Successful Ophthalmic Eye-Drop Preparation of Vancomycin-Loaded Nanoliposomes Using the Active-Loading Method

Vancomycin is the front-line defense and drug of choice for the most serious and life-threatening methicillin-resistant Staphylococcus aureus (MRSA) infections. However, poor vancomycin therapeutic practice limits its use, and there is a consequent rise of the threat of vancomycin resistance by complete loss of its antibacterial activity. Nanovesicles as a drug-delivery platform, with their featured capabilities of targeted delivery and cell penetration, are a promising strategy to resolve the shortcomings of vancomycin therapy. However, vancomycin's physicochemical properties challenge its effective loading. In this study, we used the ammonium sulfate gradient method to enhance vancomycin loading into liposomes. Depending on the pH difference between the extraliposomal vancomycin-Tris buffer solution (pH 9) and the intraliposomal ammonium sulfate solution (pH 5-6), vancomycin was actively and successfully loaded into liposomes (up to 65% entrapment efficiency), while the liposomal size was maintained at 155 nm. Vancomycin-loaded nanoliposomes effectively enhanced the bactericidal effect of vancomycin; the minimum inhibitory concentration (MIC) value for MRSA decreased 4.6-fold. Furthermore, they effectively inhibited and killed heteroresistant vancomycin-intermediate S.aureous (h-VISA) with an MIC of 0.338 μg mL^-1. Moreover, MRSA could not develop resistance against vancomycin that was loaded into and delivered by liposomes. Vancomycin-loaded nanoliposomes could be a feasible solution for enhancing vancomycin's therapeutic use and controlling the emerging vancomycin resistance.

N-Acylated Ciprofloxacin Derivatives: Synthesis and In Vitro Biological Evaluation as Antibacterial and Anticancer Agents

A novel series of N-acylated ciprofloxacin (CP) conjugates 1-21 were synthesized and screened as potential antimicrobial agents. Conjugates 1 and 2 were 1.25-10-fold more potent than CP toward all Staphylococci (minimal inhibitory concentration 0.05-0.4 μg/mL). Most of the chloro- (3-7), bromo- (8-11), and CF₃-alkanoyl (14-16) derivatives expressed higher or comparable activity to CP against selected Gram-positive strains. A few CP analogues (5, 10, and 11) were also more effective toward the chosen clinical Gram-negative rods. Conjugates 5, 10, and 11 considerably influenced the phases of the bacterial growth cycle over 18 h. Additionally, compounds 2, 4-7, 9-12, and 21 exerted stronger tuberculostatic action against three Mycobacterium tuberculosis isolates than the first-line antitubercular drugs. Amides 1, 2, 5, 6, 10, and 11 targeted gyrase and topoisomerase IV at 2.7-10.0 μg/mL, which suggests a mechanism of antibacterial action related to CP. These findings were confirmed by molecular docking studies. In addition, compounds 3 and 15 showed high antiproliferative activities against prostate PC3 cells (IC₅₀ 2.02-4.8 μM), up to 6.5-2.75 stronger than cisplatin. They almost completely reduced the growth and proliferation rates in these cells, without a cytotoxic action against normal HaCaT cell lines. Furthermore, derivatives 3 and 21 induced apoptosis/necrosis in PC3 cells, probably by increasing the intracellular ROS amount, as well as they diminished the IL-6 level in tumor cells.

An Update Review of Approaches to Multiple Action-Based Antibacterials

Many approaches are being pursued to address the major global health challenge posed by the increasing resistance of pathogenic bacteria to antibacterial agents. One of the promising approaches being investigated includes the design and development of multiple action-based small-molecule antibacterials. Aspects of this broad area have been reviewed previously, and recent developments are addressed in this update review covering the literature mainly over the past three years. Considerations encompassing drug combinations, single-molecule hybrids and prodrugs are summarised in regard to the intentional design and development of multiple-action agents with a focus on potential triple or greater activities in bacteria. The hope for such single agents or combinations of single agents is that resistance development will be significantly hindered, and they may be useful in tackling bacterial disease caused by both resistant and non-resistant bacteria.

Antibacterial and antibiofilm activity of permanently ionized quaternary ammonium fluoroquinolones

A series of quaternary ammonium fluoroquinolones was obtained by exhaustive methylation of the amine groups present at the 7-position of fluoroquinolones, including ciprofloxacin, enoxacin, gatifloxacin, lomefloxacin, and norfloxacin. The synthesized molecules were tested for their antibacterial and antibiofilm activities against Gram-positive and Gram-negative human pathogens, i.e. Staphylococcus aureus and Pseudomonas aeruginosa. The study showed that the synthesized compounds are potent antibacterial agents (MIC values at the lowest 6.25 μM) with low cytotoxicity in vitro as assessed on the BALB 3T3 mouse embryo cell line. Further experiments proved that the tested derivatives are able to bind to the DNA gyrase and topoisomerase IV active sites in a fluoroquinolone-characteristic manner. The most active quaternary ammonium fluoroquinolones, in contrast to ciprofloxacin, reduce the total biomass of P. aeruginosa ATCC 15442 biofilm in post-exposure experiments. The latter effect may be due to the dual mechanism of action of the quaternary fluoroquinolones, which also involves disruption of bacterial cell membranes. IAM-HPLC chromatographic experiments with immobilized artificial membranes (phospholipids) showed that the most active compounds were those with moderate lipophilicity and containing a cyclopropyl group at the N1 nitrogen atom in the fluoroquinolone core.

Integration of terpesomes loaded Levocetrizine dihydrochloride gel as a repurposed cure for Methicillin-Resistant Staphylococcus aureus (MRSA)-Induced skin infection; D-optimal optimization, ex-vivo, in-silico, and in-vivo studies

The intention of this work is to assess the repurposed antimicrobial impact of Levocetirizine dihydrochloride (LVC), which is a well-known antihistaminic drug, in addition, to augment the antimicrobial effect by using terpene-enriched vesicles (TPs). To investigate how various parameters affect TPs aspects, TPs were made employing the ethanol-injection-method and optimized d-optimal design. The TPs were characterized based on their entrapment efficiency percentage (EE%), particle size (PS), polydispersity index (PDI), and zeta potential (ZP). The optimum TP was submitted to more examinations. The optimum TP (TP12) showed a spherical vesicle having an EE% of 66.39 ± 0.12%, PS of 243.3 ± 4.60 nm, PDI of 0.458 ± 0.003, and ZP of 24.2 ± 0.55 mV. The in-vitro release study results demonstrated that LVC is sustainedly liberated from the optimum TP compared to LVC-solution. The ex-vivo assessment showed that LVC was released in a more sustained manner from TPs-gel related to LVC solution, optimum TP, and LVC gel. Ex-vivo visualization by confocal laser scanning microscopy showed good deposition of the fluorescein-labeled TP. Further, the in-vitro anti-bacterial effect and biofilm inhibition and detachment assessment confirmed the potency of LVC against Methicillin-resistant-Staphylococcus-aureus (MRSA). The in-silico study demonstrated that the LVC has excellent stability with other ingredients combined with it in the TPs, further, it proved that LVC is a potential candidate for treating MRSA. In-vivo assessments revealed a good antimicrobial effect toward MRSA infection. Moreover, the histopathological evaluation confirmed the safety of using TPs-gel topically. In conclusion, MRSA-related skin infections may be treated using the LVC loaded TPs-gel as a promising system.

Novel tryptanthrin derivatives with benzenesulfonamide substituents: Design, synthesis, and anti-inflammatory evaluation

Herein, two series of tryptanthrin derivatives with benzenesulfonamide substituents were designed and synthesized to discover novel anti-inflammatory agents. The anti-inflammatory activities of all derivatives were screened by evaluating their inhibitory effects on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 cells. Among them, compound 8j exhibited the best NO inhibitory activity (IC₅₀ = 1.25 ± 0.21 μM), with no obvious toxicity. Further evaluation showed that 8j could also significantly reduce the levels of pro-inflammatory cytokines interleukin-1β (IL-1β, IC₅₀ = 8.48 ± 0.23 μM) and tumor necrosis factor-α (TNF-α, IC₅₀ = 11.53 ± 0.35 μM) and downregulate the LPS-induced expression of iNOS and COX-2. Reverse docking of 8j suggested p38α as the molecular target, which is a well-known crucial player in the p38 MAPK signaling pathway that controls the transcription of pro-inflammatory mediators. Cellular thermal shift assay showed that 8j efficiently stabilized p38α in LPS-treated RAW264.7 cells. Western blot showed that inflammatory response was inhibited by 8j through inhibiting the phosphorylation of p38α and MK2 in the p38 MAPK signaling pathway. Finally, In vivo studies showed that 8j could significantly ameliorate the degree of foot swelling and knee joint pathology in adjuvant-induced arthritis (AIA) rats and reduce levels of TNF-α and IL-1β in serum, achieving the effect of protecting synovial tissue and ameliorating arthritis. These findings suggested that 8j may be a promising compound for further development of anti-inflammatory agents.

In Vitro and In Vivo Antibiofilm Activity of Red Onion Scales: An Agro-Food Waste

Red onion wastes (ROW) are valuable sources of bioactive metabolites with promising antimicrobial effects. Methicillin-resistant Staphylococcus aureus (MRSA) infections are a growing risk in hospitals and communities. This study aims to investigate the in vitro and in vivo antibiofilm activities of the acidified ethanolic extract of red onion scales (RO-T) and its fractions against an MRSA vaginal colonization model. The RO-T extract, as well as its anthocyanin-rich fraction (RO-P) and flavonoid-rich fraction (RO-S), recorded a promising antibacterial activity against highly virulent strains of bacteria (MRSA, Acinetobacter baumannii, Escherichia coli and Pseudomonas aeruginosa). RO-S showed the highest antibacterial activity (MBC of 0.33 ± 0.11 mg/mL) against MRSA USA300 and significantly eradicated its biofilm formation with an IC₅₀ of 0.003. Using a rat model, in vivo assessment on all samples, which were formulated as a hydrogel, revealed a significant reduction of MRSA bacterial load recovered from an infected vagina compared to that of the negative control group (NCG). RO-T extract and vancomycin groups recorded the highest antibacterial activity with a bacterial load 2.998 and 3.358 logs lower than the NCG, respectively. The histopathological investigation confirmed our findings. RO-T and RO-S were standardized for their quercetin content. Finally, ROW offers a new potent antibiofilm agent mostly due to its high quercetin content.

Unveiling Antimicrobial and Antioxidant Compositional Differences between Dukkah and Za'atar via SPME-GCMS and HPLC-DAD

Interest in plant-based diets has been on the rise in recent years owing to the potential health benefits of their individual components and the notion that plant-based diets might reduce the incidence of several diseases. Egyptian dukkah and Syrian za’atar are two of the most historic and famous Middle Eastern herbal blends used for their anti-inflammatory, hypolipidemic, and antidiabetic effects. Headspace SPME-GCMS and HPLC-DAD were adopted for characterizing the aroma profile and phenolic compounds of both herbal blends, respectively. Further, vapor-phase minimum inhibitory concentration was employed for assessing each blend’s antibacterial potential, while their antioxidant potential was estimated via in vitro antioxidant assays. SPME headspace analysis indicated the abundance of ethers and monoterpene hydrocarbons, while HPLC revealed the presence of several phenolics including rosmarinic acid, ferulic acid, and rutin. Biological investigations affirmed that vapor-phase of the tested blends exhibited antibacterial activities against Gram-positive and Gram-negative pathogens, while the antioxidant potential of the blends was investigated and expressed as Trolox (125.15 ± 5.92 to 337.26 ± 13.84 μM T eq/mg) and EDTA (18.08 ± 1.62 to 51.69 41 ± 5.33 μM EDTA eq/mg) equivalent. The presented study offers the first insight into the chemical profile and biological activities of both dukkah and za’atar.

New potent ciprofloxacin-uracil conjugates as DNA gyrase and topoisomerase IV inhibitors against methicillin-resistant Staphylococcus aureus

A series of ciprofloxacin-uracil conjugates 5a-t were synthesized and identified by ¹H NMR, ¹³C NMR, mass spectroscopy and elemental analyses. The antibacterial results revealed that the new derivatives exhibited better activity against Gram-positive than the Gram-negative strains; most of the target compounds exhibited good activities against S. aureus ATCC 6538. Compounds 5b and 5g possess the highest activities with MICs of 1.25 and 2.37 µM, respectively, which are more potent than the parent drug ciprofloxacin, MIC, 7.58 µM. In addition, they also exhibited potent activities against MRSA AUMC 261 with MICs, 0.031 and 0.046 µM respectively, higher than ciprofloxacin with MIC, 0.57 µM. Moreover, compounds 5b and 5g showed potent inhibitory activities against DNA gyrase (IC₅₀ = 1.72 and 5.72 µM) and topoisomerase IV (4.36 and 7.77 µM) compared to ciprofloxacin with IC₅₀ values 0.66 and 8.16 µM, respectively. The molecular docking study revealed that compounds 5b and 5g may formed stable interaction with the active sites of DNA gyrase and topoisomerase IV similar to ciprofloxacin. Hence, 5b and 5g are considered promising antibacterial candidated against MRSA AUMC 261 strains that requires further optimization.

Fluoroquinolones Hybrid Molecules as Promising Antibacterial Agents in the Fight against Antibacterial Resistance

The emergence of bacterial resistance has motivated researchers to discover new antibacterial agents. Nowadays, fluoroquinolones keep their status as one of the essential classes of antibacterial agents. The new generations of fluoroquinolones are valuable therapeutic tools with a spectrum of activity, including Gram-positive, Gram-negative, and atypical bacteria. This review article surveys the design of fluoroquinolone hybrids with other antibacterial agents or active compounds and underlines the new hybrids' antibacterial properties. Antibiotic fluoroquinolone hybrids have several advantages over combined antibiotic therapy. Thus, some challenges related to joining two different molecules are under study. Structurally, the obtained hybrids may contain a cleavable or non-cleavable linker, an essential element for their pharmacokinetic properties and mechanism of action. The design of hybrids seems to provide promising antibacterial agents helpful in the fight against more virulent and resistant strains. These hybrid structures have proven superior antibacterial activity and less susceptibility to bacterial resistance than the component molecules. In addition, fluoroquinolone hybrids have demonstrated other biological effects such as anti-HIV, antifungal, antiplasmodic/antimalarial, and antitumor activity. Many fluoroquinolone hybrids are in various phases of clinical trials, raising hopes that new antibacterial agents will be approved shortly.