Discovery of novel arylethenesulfonyl fluorides as potential candidates against methicillin-resistant of Staphylococcus aureus (MRSA) for overcoming multidrug resistance of bacterial infections

Design and synthesis of benzothiazole aryl urea derivatives as potent anti-staphylococcal agents targeting autolysin-mediated peptidoglycan hydrolases

Novel benzothiazole aryl ureas were designed and synthesized as anti-MRSA agents targeting peptidoglycan (PG) hydrolases (autolysins). Structural simplification of prior benzothiazole-urea hybrids yielded compounds 4a, 7a and 11a bearing p-CF3 on phenyl ring demonstrating narrow-spectrum activity against Gram-positive bacteria including clinical methicillin-resistant S. aureus (MRSA). The primary autolysin in S. aureus, AtlA, mediates peptidoglycan hydrolase activity critical for bacterial growth, division, and cell wall remodeling. Mechanistic studies revealed that 4a down-regulated autolysin-related genes RNAIII and walR, disrupting peptidoglycan homeostasis. Knockout of atlA (a key autolysin gene) impaired 4a's efficacy, confirming autolysins as critical targets. Docking indicated that 4a binds to AtlA via hydrogen bonds, Pi-Pi, and hydrophobic interactions. In vivo, 4a significantly reduced bacterial load in a murine abdominal infection model, outperforming vancomycin at 10 mg/kg with lower cytotoxicity. Additionally, 4a disrupted MRSA biofilms, suppressed hemolytic toxin production, and alleviated inflammation in infected mice. These findings underscore AtlA as a promising therapeutic target and highlight benzothiazole phenyl urea as a scaffold for developing innovative anti-staphylococcal agents.

Discovery of A Synthetic Hub for Regio- and Stereoselective Construction of Triazolyl Vinyl Sulfonyl Fluorides

A new sulfonyl fluoride reagent 1-bromobut-3-ene-1,3-disulfonyl difluoride (BEDF) was developed. This unique reagent possesses two clickable functionalities to be used for both azide-alkyne cycloaddition click and SuFEx click reactions. This new reagent was applied for the regioselective construction of a class of novel triazolyl vinyl sulfonyl fluorides in which the C-4 position 1H-1,2,3-triazoles were functionalized with vinyl sulfonyl fluorides of exclusively E-configuration.

Synthesis of α-Bromo Arylethyl Sulfonyl Fluorides and β-Arylethenesulfonyl Fluorides via Copper-Catalyzed Meerwein Arylation

A practical copper-catalyzed process for the synthesis of the β-arylethenesulfonyl fluorides is described. A series of α-bromo arylethyl sulfonyl fluorides was prepared via Meerwein reaction from arenediazonium tetrafluoroborates and ethenesulfonyl fluoride (ESF) under mild conditions. The following β-arylethenesulfonyl fluorides were further obtained through a β-elimination reaction. This protocol features excellent regio- and stereoselectivity and broad substrate scope.

A portal to highly valuable indole-functionalized vinyl sulfonyl fluorides and allylic sulfonyl fluorides

A practical and efficient method for the C-3 site selective alkenylation of indoles was developed for constructing novel indole-functionalized vinyl sulfonyl fluorides and indolyl allylic sulfonyl fluorides. The reaction is accomplished with exclusive regio- and stereoselectivity without using transition metal catalysts, providing novel products of great potential value in medicinal chemistry, chemical biology, and drug discovery.

Chemoselective Reactions of Functionalized Sulfonyl Halides

Chemoselective transformations of functionalized sulfonyl fluorides and chlorides are surveyed comprehensively. It is shown that sulfonyl fluorides provide an excellent selectivity control in their reactions. Thus, numerous conditions are tolerated by the SO2 F group - from amide and ester formation to directed ortho-lithiation and transition-metal-catalyzed cross-couplings. Meanwhile, sulfur (VI) fluoride exchange (SuFEx) is also compatible with numerous functional groups, thus confirming its title of "another click reaction". On the contrary, with a few exceptions, most transformations of functionalized sulfonyl chlorides typically occur at the SO2 Cl moiety.

The vinyl sulfone motif as a structural unit for novel drug design and discovery

INTRODUCTION

Vinyl sulfones are a special sulfur-containing structural unit that have attracted considerable attention, owing to their important role in serving as key structural motifs of various biologically active compounds as well as serving as versatile building blocks for organic transformations. The synthetic strategy of vinyl sulfone derivatives has been substantially upgraded over the past 30 years, and the wide application of this functional group in drug design and discovery has been promoted.

AREA COVERED

In this review, the authors review the application of vinyl sulfones in drug discovery and select optimized compounds which might have significant impact or potential inspiration for drug design.

EXPERT OPINION

Vinyl sulfones have been reported to target various macromolecular targets via non-covalent or covalent interactions, including multiple kinases, tubulin, cysteine protease, transcription factor, and so on. Thus, it has been significantly applied as a privileged scaffold in the design of anticancer, anti-infective, anti-inflammatory, and neuroprotective agents. However, much work remains to be done to improve the drug-like properties, such as chemical and metabolic stability, ADME, and toxicity. Besides, the chemical space of vinyl sulfones needs to be expanded, including but not limited to the design of constrained endocyclic and exocyclic vinyl sulfones.

Review of triazole scaffolds for treatment and diagnosis of Alzheimer's disease

Triazole scaffolds, a series of 5-membered heterocycles, are well known for their high efficacy, low toxicity, and superior pharmacokinetics. Alzheimer's disease (AD) is the first neurodegenerative disorder with complex pathological mechanisms. Triazole, as an aromatic group with three nitrogen atoms, forms polar and non-polar interactions with diverse key residues in the receptor-ligand binding procedure, and has been widely used in the molecular design in the development of anti-AD agents. Moreover, considering the simple synthesis approaches, triazole scaffolds are commonly used to link two pharmacodynamic groups in one chemical molecule, forming multi-target directed ligands (MTDLs). Furthermore, the click reaction between azide- and cyano-modified enzyme and ligand provides feasibility for the new modulator discovery, compound tissue distribution evaluation, enzyme localization, and pharmacological mechanism study, promoting the diagnosis of AD course.

Discovery of (E)-2-Methoxyethene-1-sulfonyl Fluoride for the Construction of Enaminyl Sulfonyl Fluoride

A new sulfonyl fluoride reagent (E)-2-methoxyethene-1-sulfonyl fluoride (MeO-ESF) was developed and successfully applied for the construction of enaminyl sulfonyl fluoride (N-ESF). This protocol provides highly atom-economical access to diverse N-ESF and produces CH₃OH as the sole byproduct under mild and environmentally benign conditions.

Distribution of Biocide Resistance Genes and Association with Clonal Complex Genotypes in Staphylococcus aureus Isolated from School-Age Children in Guangzhou

Purpose

Chlorhexidine and mupirocin are often prescribed to children in affected communities to prevent colonization and transmission of Staphylococcus aureus, but this has led to an increasing rate of biocide resistance. In this study, we aimed to determine the distribution of biocide resistance genes among S. aureus isolates from school-age children in Guangzhou, investigate chlorhexidine gluconate and mupirocin susceptibility and clonal complex (CC) genotypes in strains carrying biocide-resistance genes, and further explore the role of biofilms in this resistance.

Patients and Methods

Antibiotic resistance and multilocus sequence genotyping were performed on 722 S. aureus isolates from previous study. The distribution of nine biocide genes (qacA/B, mupA, mepA, sepA, norA, lmrS, smr, mupB, qacG) was determined by PCR. Isolates carrying qacA/B or mupA genes were further tested for susceptibility to chlorhexidine gluconate (CHG) and mupirocin and biofilm formation abilities.

Results

The most prevalent of the nine biocide resistance genes were mepA (95.57%), followed by norA (78.81%), lmrS (77.01%), and sepA (58.17%). The qacG gene was not detected. Distribution of sepA was significantly decreased in CC30 and CC45 genotypes, and presence of sepA was associated with resistance to antibiotics such as CLI, ERY, TCY, SXT, CIP, and LVX. In addition, 64 (94.1%, n=68) qacA/B+ isolates showed CHG resistance, 12 (100.0%, n=12) mupA+ isolates were mupirocin resistant, and 4 (80%, n=5) and 5 (100%, n=5) qacA/B+mupA+ isolates were CHG and mupirocin resistant, respectively. Of these 85 isolates, 98.8% (n=84) had different degrees of biofilm-forming abilities, which were positively associated with CHG and mupirocin resistance.

Conclusion

The distribution of biocide resistance genes was associated with special CCs. The qacA/B and mupA genes are highly associated with resistance to CHG and mupirocin, and biofilm formation was found to contribute to this biocide resistance.

The Anti-MRSA Activity of Phenylthiazoles: A Comprehensive Review

Antimicrobial resistance is an aggravating global issue therefore it has been under extensive research in an attempt to reduce the number of antibiotics that are constantly reported as obsolete jeopardizing the lives of millions worldwide. Thiazoles possess a reputation as one of the most diverse biologically active nuclei, and phenylthiazoles are no less exceptional with an assorted array of biological activities such as anthelmintic, insecticidal, antimicrobial, antibacterial, and antifungal activity. Recently phenyl thiazoles came under the spotlight as a scaffold having strong potential as an anti-MRSA lead compound. It is a prominent pharmacophore in designing and synthesizing new compounds with antibacterial activity against multidrug-resistant bacteria such as MRSA, which is categorized as a serious threat pathogen, that exhibited concomitant resistance to most of the first-line antibiotics. MRSA has been associated with soft tissue and skin infections resulting in high death rates, rapid dissemination, and loss of millions of dollars of additional health care costs. In this brief review, we have focused on the advances of phenylthiazole derivatives as potential anti-MRSA from 2014 to 2021. The review encompasses the effect on biological activity due to combining this molecule with various synthetic pharmacophores. The physicochemical aspects were correlated with the pharmacokinetic properties of the reviewed compounds to reach a structure-activity relationship profile. Lead optimization of phenyl thiazole derivatives has additionally been outlined where the lipophilicity of the compounds was balanced with the metabolic stability and oral solubility to aid the researchers in medicinal chemistry, design, and synthesizing effective anti- MRSA phenylthiazoles in the future.

Fluorosulfate-containing pyrazole heterocycles as selective BuChE inhibitors: structure-activity relationship and biological evaluation for the treatment of Alzheimer's disease

Novel scaffolds are expected to treat Alzheimer’s disease, pyrazole-5-fluorosulfates were found as selective BuChE inhibitors. Compounds K1–K26 were assayed for ChE inhibitory activity, amongst them, compound K3 showed potent BuChE and hBuChE inhibition (IC₅₀ = 0.79 μM and 6.59 μM). SAR analysis showed that 1-, 3-, 4-subtituent and 5-fluorosulfate of pyrazole ring affected BuChE inhibitory activity. Molecular docking showed that the fluorosulfate increased the binding affinity of hBuChE through π-sulphur interaction. Compound K3 was a reversible, mixed and non-competitive BuChE inhibitor (K_i = 0.77 μM) and showed remarkable neuroprotection, safe toxicological profile and BBB penetration. In vivo behavioural study showed that K3 treatment improved the Aβ_1 − 42-induced cognitive impairment, and significantly prevented the effects of Aβ_1 − 42 toxicity. Therefore, selective BuChE inhibitor K3 has potential to be further developed as AD therapeutics.

The synthesis and application of a colour-switch β-arylethenesulfonyl fluoride fluorescent probe in the detection of serum albumin

Proteins play a pivotal role in regulating important physiological processes and serve as important biomarkers for many diseases. Herein, we present a new strategy for bovine serum albumin (BSA) detection using a novel colour-switch fluorescent probe CPV-ESF ((E)-2-(4-((Z)-1-cyano-2-(4-(diethylamino)phenyl)vinyl)phenyl)ethene-1-sulfonyl fluoride). CPV-ESF reacts with nucleophilic amino acids of BSA via 1,4-Michael addition click chemistry to create a covalently linked CPV-ESF:BSA complex, which can be easily detected by a fluorescence colour-switch response. The sensing mechanism, sensitivity and selectivity of CPV-ESF for BSA detection as well as its application for cell imaging have been investigated.

A reductive dehalogenative process for chemo- and stereoselective synthesis of 1,3-dienylsulfonyl fluorides

A method for the mild and efficient synthesis of 1,3-dienylsulfonyl fluorides was developed via dehalogenation of α-halo-1,3-dienylsulfonyl fluorides in the presence of zinc powder and acetic acid, achieving exclusive chemo- and stereoselectivities. This protocol was successfully applied to the synthesis of heterocyclic dienylsulfonyl fluorides and polyene sulfonyl fluoride.

Synthesis of a β-Arylethenesulfonyl Fluoride-Functionalized AIEgen for Activity-Based Urinary Trypsin Detection

Trypsin is one of the most important enzymes of the digestive system produced by the pancreatic acinar cells. Abnormal trypsin activity will affect pancreatic function, resulting in the corresponding pathological changes in the human body. Herein, we present a strategy based on the ensemble of a novel dual warhead probe HPC-ESF and the natural trypsin substrate bovine serum albumin (BSA) for the detection of trypsin activity including in real urine samples. The β-arylethenesulfonyl bearing HPC-ESF is nonemissive when dissolved in aqueous solution but becomes highly fluorescent upon conjugation to BSA through covalent bond formation with nucleophilic amino acids to create the HPC-ESF:BSA sensing system. The HPC-ESF:BSA complex can be hydrolyzed in the presence of trypsin, which results in a distinct fluorescence decrease in correlation with trypsin concentration and thus allows the detection of trypsin. Compared to previous methods, our covalent approach is simple to prepare and highly reliable. Our work will provide a different avenue for researchers to design fluorescent sensors based on a covalent labeling strategy, enriching the small library of functional groups available for such applications.

Regio- and Stereoselective Installation of Bromide onto Vinyl Sulfonyl Fluorides: Construction of a Class of Versatile Sulfur Fluoride Exchange Hubs

A convenient protocol for the exclusively regio- and stereoselective installation of a bromine atom on the 2-arylvinylsulfonyl fluorides using lithium bromide (LiBr) as the bromine source was described, providing (Z)-1-bromo-2-arylethene-1-sulfonyl fluorides (Z-BASF) with versatile reactive handles (bromide, vinyl, and sulfonyl fluoride) in ≤88% yield. Meanwhile, Z-BASF molecules displayed various reactivities in a series of chemical transformations.

Novel benzothiazole‒urea hybrids: Design, synthesis and biological activity as potent anti-bacterial agents against MRSA

Novel benzothiazole‒urea hybrids were designed, synthesized and evaluated their anti-bacterial activity. They only exhibited anti-bacterial activity against Gram-positive bacteria, including clinical methicillin-resistant S. aureus (MRSA), compounds 5f, 5i, 8e, 8k and 8l exhibited potent activity (MIC = 0.39 and 0.39/0.78 μM against SA and MRSA, respectively). Crystal violet assay showed that compounds 5f, 8e and 8l not only inhibited the formation of biofilms but also eradicated preformed biofilms. Compound 8l had membrane disruption, little propensity to induce resistance, benign safety and in vivo anti-MRSA efficacy in a mouse model of abdominal infection. Therefore, our data demonstrated the potential to advance benzothiazole‒urea hybrids as a new class of antibiotics.

Fascaplysin derivatives binding to DNA via unique cationic five-ring coplanar backbone showed potent antimicrobial/antibiofilm activity against MRSA in vitro and in vivo

Methicillin-resistant Staphylococcus aureus (MRSA) is considered as one of the most dangerous clinical pathogens. Biofilms forming ability of MRSA is also a major cause of drug resistance. Hence, it is in urgent need to develop novel antibacterial/antibiofilm drugs. Fascaplysin with a unique cationic five-ring coplanar backbone is emerging as a potential antibacterial compound. In this study, aiming at developing novel and more effective agents, a series of fascaplysin derivatives and their corresponding β-carboline precursors have been synthesized. Then their antibacterial/antibiofilm activity and mechanisms against MRSA were investigated for the first time. The results showed that most fascaplysins rather than β-carboline precursors exhibit superior antimicrobial activity against MRSA ATCC43300, demonstrating the important role of cationic five-ring coplanar backbone playing in antibacterial activity. Among them, 14 and 18 are the most potent compounds with MIC value of 0.098 μg/ml (10-fold lower than vancomycin), and 18 featuring the lowest toxicity. Subsequent mechanisms exploration indicates that 18 has relatively stronger ability to destroy bacterial cell wall and membrane, higher binding affinity to bacterial genomic DNA. Molecular docking study revealed that besides the key role of cationic five-ring coplanar backbone, introduction of N-aryl amide at 9-position of fascaplysin promoted the combination of compound 18 and DNA via additional π-π stacking and hydrogen bonding of the naphthyl group. Moreover, fascaplysins could inhibit MRSA biofilm formation in vitro and bacterial infection in vivo. All these results illustrate that fascaplysin derivative 18 is a strong and safe multi-target antibacterial agent, which makes it an attractive candidate for the treatment of MRSA and its biofilm infections.

Structure-activity relationship, in vitro and in vivo evaluation of novel dienyl sulphonyl fluorides as selective BuChE inhibitors for the treatment of Alzheimer's disease

To discover novel scaffolds as leads against dementia, a series of δ-aryl-1,3-dienesulfonyl fluorides with α-halo, α-aryl and α-alkynyl were assayed for ChE inhibitory activity, in which compound A10 was identified as a selective BuChE inhibitor (IC50 = 0.021 μM for eqBChE, 3.62 μM for hBuChE). SAR of BuChE inhibition showed: (i) o- > m- > p-; -OCH3 > -CH3 > -Cl (-Br) for δ-aryl; (ii) α-Br > α-Cl, α-I. Compound A10 exhibited neuroprotective, BBB penetration, mixed competitive inhibitory effect on BuChE (Ki = 29 nM), and benign neural and hepatic safety. Treatment with A10 could almost entirely recover the Aβ1-42-induced cognitive dysfunction to the normal level, and the assessment of total amount of Aβ1-42 confirmed its anti-amyloidogenic profile. Therefore, the potential BuChE inhibitor A10 is a promising effective lead for the treatment of AD.

A review: antimicrobial properties of several medicinal plants widely used in Traditional Chinese Medicine

Due to the dramatic increase in the use of antibiotics and growing health threat of bacterial resistance to many commonly used antibiotics, many studies have been directed at developing new and effective antibacterial compounds, among which many new, natural, and effective antibacterial compounds discovered from medicinal plants have drawn great interest and raised new hope for treating the challenges of antibiotic resistance. This review aimed to summarize the most important and widely used medicinal plants that were reported to have antibacterial activities. A general literature search from 2010 to 2020 was conducted using different databases, including Science Direct, Web of Science, and PubMed. According to the literature, three medicinal plants with outstanding antibacterial activities, Taraxacum officinale, Coptis Rhizome, and Scutellaria baicalensis, were screened and reviewed by prioritization. The extraction methods, antibacterial activities of different parts of plants or the plant-derived compounds, spectra of antibacterial activities, and toxicity were described, respectively. However, the antibacterial activities of the extracts or pure compounds as reported in the reviewed literature were mostly based on in vitro assays, and moreover, the deeper antibacterial mechanisms have not been elucidated clearly. Therefore, further studies are required in the fields of purification and identification of the antibacterial compounds, its mechanisms of action, and synergistic effects in combination with other antibacterial drugs, which may be helpful in the development of new antibacterial drugs.

A key review on oxadiazole analogs as potential methicillin-resistant Staphylococcus aureus (MRSA) activity: Structure-activity relationship studies

Methicillin-resistant Staphylococcus aureus (MRSA) is becoming dangerous to human beings due to easy transmission mode and leading to the difficult-to-treat situation. The rapid resistance development of MRSA to many approved antibiotics is of major concern. There is a lot of scope to develop novel, efficient, specific, and nontoxic drug candidates to fight against MRSA isolates. The interesting molecular structure and adaptable feature of oxadiazole moiety which are bioisosteres of esters and amides, and these functional groups show improved resistance to esterases mediated hydrolytic cleavage, attracting researchers to develop required novel antibiotics based on oxadiazole core. This review summarizes the developments of oxadiazole-containing derivatives as potent antibacterial agents against multidrug-resistant MRSA strains and discussing the structure-activity relationship (SAR) in various directions. The current survey is the highlight of the present scenario of oxadiazole hybrids on MRSA studies, covering articles published from 2011 to 2020. This collective information may become a good platform to plan and develop new oxadiazole-based small molecule growth inhibitors of MRSA with minimal side effects.

Methicillin-resistance Staphylococcus aureus (MRSA) Pyruvate kinase (PK) inhibitors and Their Antimicrobial Activities

Resistance to antibiotics has been widely existed in the health care and community setting, thus developing a novel aspect of new antibiotics is urgently necessary. Methicillin-resistance Staphylococcus aureus (MRSA) Pyruvate kinase (PK) is crucial to the survive of bacterial, making it a novel antimicrobial target. In the past decade, most reported PK inhibitors including indole, flavonoid, phenazine derivative from natural product small molecules or their analogues, or virtual screening from small molecule compound library. This review covers the PK inhibitors and their antimicrobial activities reported from the beginning of 2011 through the middle of 2020. The Structure Activity Relationships (SARs) was discussed briefly as well.

1,2,4-Oxadiazole topsentin analogs as staphylococcal biofilm inhibitors targeting the bacterial transpeptidase sortase A

The inhibition or prevention of biofilm formation represents an emerging strategy in the war against antibiotic resistance, interfering with key players in bacterial virulence. This approach includes the inhibition of the catalytic activity of transpeptidase sortase A (Srt A), a membrane enzyme responsible for covalently attaching a wide variety of adhesive matrix molecules to the peptidoglycan cell wall in Gram-positive strains. A new series of seventeen 1,2,4-oxadiazole derivatives was efficiently synthesized and screened as potential new anti-virulence agents. The ability of inhibiting biofilm formation was evaluated against both Gram-positive and Gram-negative pathogens. Remarkably, all these compounds inhibited S. aureus and/or P. aeruginosa biofilm formation in a dose dependent manner, with 50% biofilm inhibitory concentrations (BIC50s) below 10 μM for the most active compounds. Inhibition of SrtA was validated as one of the possible mechanisms of action of these new 1,2,4-oxadiazole derivatives, in the tested Gram-positive pathogen, using a specific enzymatic assay for a recombinant S. aureus SrtA. The three most active compounds, eliciting BIC50 values for S. aureus ATCC 25923 between 0.7 and 9.7 μM, showed a good activity toward the enzyme eliciting IC50 values ranging from 2.2 to 10.4 μM.

Pyrazole-based analogs as potential antibacterial agents against methicillin-resistance staphylococcus aureus (MRSA) and its SAR elucidation

Methicillin-resistant Staphylococcus aureus (MRSA) is becoming lethal to humanity due to easy transmission and difficult-to-treat skin and flimsy diseases. The most threatening aspect is the rapid resistance development of MRSA to any approved antibiotics, including vancomycin. The development of new, efficient, and nontoxic drug candidate to fight against MRSA isolates is the need of the hour. The intriguing molecular structure and versatile bioactive pyrazole core attracting to development required novel antibiotics. This review presents the decade developments of pyrazole-containing derivatives with a broad antibacterial movement against diverged bacterial strains. In specific, we correlated the efficacy of structurally diversified pyrazole analogs against MRSA and discussed different angles of structure-activity relationship (SAR). The current survey highlights pyrazole hybrids' present scenario on MRSA studies, covering articles published from 2011 to 2020. This collective information may become an excellent platform to plan and develop new pyrazole-based small MRSA growth inhibitors with minimal side effects.

Recent accomplishments on the synthetic/biological facets of pharmacologically active 1H-1,2,3-triazoles

The continuous demand of medicinally important scaffolds has prompted the synthetic chemists to identify simple and efficient routes for their synthesis. 1H-1,2,3-triazole, obtained by highly versatile, efficacious and selective "Click Reaction" has become a synthetic/medicinal chemist's favorite not only because of its ability to mimic different functional groups but also due to enhancement in the targeted biological activities. Triazole ring has also been shown to play a critical role in biomolecular mimetics, fragment-based drug design, and bioorthogonal methodologies. In addition, the availability of triazole containing drugs such as fluconazole, furacyclin, etizolam, voriconazole, triozolam etc. in market has underscored the potential of this biologically enriched core in expediting development of new scaffolds. The present review, therefore, is an attempt to highlight the recent synthetic/biological advancements in triazole derivatives that could facilitate the in-depth understanding of its role in the drug discovery process.

Novel benzofuran-based sulphonamides as selective carbonic anhydrases IX and XII inhibitors: synthesis and in vitro biological evaluation

Pursuing on our efforts toward searching for efficient hCA IX and hCA XII inhibitors, herein we report the design and synthesis of new sets of benzofuran-based sulphonamides (4a,b, 5a,b, 9a-c, and 10a-d), featuring the zinc anchoring benzenesulfonamide moiety linked to a benzofuran tail via a hydrazine or hydrazide linker. All the target benzofurans were examined for their inhibitory activities toward isoforms hCA I, II, IX, and XII. The target tumour-associated hCA IX and XII isoforms were efficiently inhibited with KIs spanning in ranges 10.0-97.5 and 10.1-71.8 nM, respectively. Interestingly, arylsulfonehydrazones 9 displayed the best selectivity toward hCA IX and XII over hCA I (SIs: 39.4-250.3 and 26.0-149.9, respectively), and over hCA II (SIs: 19.6-57.1 and 13.0-34.2, respectively). Furthermore, the target benzofurans were assessed for their anti-proliferative activity, according to US-NCI protocol, toward a panel of sixty cancer cell lines. Only benzofurans 5b and 10b possessed selective and moderate growth inhibitory activity toward certain cancer cell lines.

Synthesis and evaluation of antimicrobial and anticancer activities of 3-phenyl-1-phenylsulfonyl pyrazoles containing an aminoguanidine moiety

A series of 3-phenyl-1-phenylsulfonyl pyrazoles containing an aminoguanidine moiety was designed, synthesized, and evaluated for their antimicrobial and anticancer activities. The majority of the target compounds showed broad-spectrum antimicrobial activity against the tested strains, with minimum inhibitory concentration (MIC) values ranging from 2 to 64 μg/ml. Compound 5k, showing the most potent antimicrobial activity against Bacillus subtilis CMCC 63501 and multidrug-resistant Staphylococcus aureus ATCC 43300 with an MIC value of 2 μg/ml, was the most promising one in this series. It was also effective for S. aureus ATCC 33591 and multidrug-resistant Escherichia coli ATCC BAA-196 at higher concentrations. The bactericidal time-kill kinetics test illustrated that compound 5k had rapid bactericidal potential. Docking results exhibited that compound 5k showed various kinds of binding to the FabH receptor, reflecting that 5k could bind with the active site well. All compounds showed excellent activity against the investigated cancer cells, with IC₅₀ values ranging from 1.90 to 54.53 µM. Among them, compound 5f showed prominent cytotoxicity with IC₅₀  = 1.90 µM against A549 cells, while exhibiting lower inhibitory activity against 293T cells (IC₅₀  = 41.72 µM), indicating that it has the potential for a good therapeutic index as an anticancer drug.

Novel anti-tubercular and antibacterial based benzosuberone-thiazole moieties: Synthesis, molecular docking analysis, DNA gyrase supercoiling and ATPase activity

Herein, molecular hybridization strategy was utilized in the design of new benzosuberone-thiazole derivatives. The structures of the synthesized hybrids were determined on the basis of elemental and spectral analyses. These compounds were evaluated for their antibacterial activities against five bronchitis causing bacteria in addition to their anti-tubercular activities. Most compounds revealed promising activities. Amongst active compounds, benzosuberone-dithiazole derivatives 22a and 28 with MIC value = 1.95 µg/ml against H. influenza, M. pneumonia, and B. pertussis displayed four times the activity of ciprofloxacin (MIC = 7.81 µg/ml) against H. influenza, twice the activity of ciprofloxacin (MIC = 3.9 µg/ml) against M. pneumonia and were equipotent to ciprofloxacin against B. pertussis (MIC = 1.95 µg/ml). Additionally, benzosuberone-dithiazole derivatives 22a and 27 were the most promising anti-tubercular among the tested compounds with MIC values of 0.12 and 0.24 µg/ml, respectively against sensitive M. tuberculosis in addition to high activity against resistant strain of M. tuberculosis (MIC = 0.98 and 1.95 µg/ml, respectively) compared to isoniazid (MIC = 0.12 µg/ml against sensitive M. tuberculosis and no activity against resistant M. tuberculosis). Cytotoxicity study of the active dithiazole derivatives 22a, 27 and 28 against normal human lung cells (WI-38) indicated their high safety profile as showed from their high IC₅₀ values (IC₅₀ = 107, 74.8, and 117 µM, respectively). Furthermore, DNA gyrase supercoiling and ATPase activity assays showed that 22a, 27 and 28 have the potential to inhibit DNA gyrase at low micromolar levels (IC₅₀ = 3.29-15.64 µM). Molecular docking analysis was also carried out to understand the binding profiles of the synthesized compounds into the ATPase binding sites of bacterial and mycobacterial DNA gyraseB.

1,2,4-Triazole hybrids with potential antibacterial activity against methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) has developed numerous mechanisms of virulence and strategies to evade the human immune system, and it can be transmitted between humans, animals, and the environment. Thus, MRSA is an important cause of morbidity and mortality in both hospitals and in the community, creating an urgent demand for the development of novel anti-MRSA candidates. The 1,2,4-triazole nucleus is a bioisostere of amide, ester, and carboxylic acid, and the 1,2,4-triazole ring is found in many compounds with diverse biological effects. 1,2,4-Triazole derivatives could exert their antibacterial activity through inhibition of efflux pumps, filamentous temperature-sensitive protein Z, penicillin-binding protein, DNA gyrase, and topoisomerase IV, and they play an important role in the discovery of novel antibacterial agents. Among them, 1,2,4-triazole hybrids, which have the potential to exert dual/multiple mechanisms of action, possess a promising broad-spectrum antibacterial activity against a panel of clinically important drug-resistant pathogens including MRSA. This review outlines the recent developments of 1,2,4-triazole hybrids with a potential anti-MRSA activity, covering articles published between 2010 and 2020. The mechanisms of action, critical aspects of their design, and structure-activity relationships are also discussed.

Inhibitory mechanism of BAC-IB17 against β-lactamase mediated resistance in methicillin-resistant Staphylococcus aureus and application as an oncolytic agent

Cancer remains a foremost cause of deaths worldwide, despite several advances in the medical science. The conventional chemotherapeutic methods are not only harmful for normal body cells but also become inactive due to the development of resistance by cancer cells. Therefore, the demand of safe anticancer agents is increasing and enforced the bottomless research on the bacteriocins. Several studies have reported the selective anticancer property of bacteriocins. Current research is the contribution to explore the exact mechanism of action and in vitro application of bacteriocin (BAC-IB17) as an oncolytic agent. In this study, β-lactamase mediated resistance of methicillin resistant Staphylococcus aureus (MRSA) was studied and inhibitory mechanism of MRSA by BAC-IB17 was investigated. Cytotoxic studies were conducted to analyze the anticancerous potential of BAC-IB17. Results revealed that BAC-IB17 inhibited the β-lactamase and produced profound effect on the membrane integrity of MRSA confirmed by scanning electron microscope (SEM). FTIR spectroscopic analysis revealed the changes in the functional groups of bacterial cells before and after treatment with BAC-IB17. BAC-IB17 also found anticancer in nature as it kills HeLa cell lines with the IC₅₀ value of 12.5 μg mL^-1 with no cytotoxic effect on normal cells at this concentration. This specific anticancer property of BAC-IB17 will make it a promising candidate for the treatment of cancer after further clinical trials. Moreover, BAC-IB17 may control MDR bacteria responsible for the secondary complications in cancer patients.

New marine-derived indolymethyl pyrazinoquinazoline alkaloids with promising antimicrobial profiles

Due to the emergence of multidrug-resistant pathogenic microorganisms, the search for novel antimicrobials is urgent. Inspired by marine alkaloids, a series of indolomethyl pyrazino [1,2-b]quinazoline-3,6-diones was prepared using a one-pot microwave-assisted multicomponent polycondensation of amino acids. The compounds were evaluated for their antimicrobial activity against a panel of nine bacterial strains and five fungal strains. Compounds 26 and 27 were the most effective against Staphylococcus aureus ATCC 29213 reference strain with MIC values of 4 μg mL⁻¹, and a methicillin-resistant Staphylococcus aureus (MRSA) isolate with MIC values of 8 μg mL⁻¹. It was possible to infer that enantiomer (−)-26 was responsible for the antibacterial activity (MIC 4 μg mL⁻¹) while (+)-26 had no activity. Furthermore, compound (−)-26 was able to impair S. aureus biofilm production and no significant cytotoxicity towards differentiated and non-differentiated SH-SY5Y cells was observed. Compounds 26, 28, and 29 showed a weak antifungal activity against Trichophyton rubrum clinical isolate with MIC 128 μg mL⁻¹ and presented a synergistic effect with fluconazole.

Indolomethyl pyrazino [1,2-b]quinazoline-3,6-diones were prepared using a one-pot multicomponent polycondensation of amino acids and were evaluated for their antimicrobial activity against a panel of nine bacterial strains and five fungal strains.

Genetic Characterization of Methicillin-Resistant Staphylococcus aureus Isolates from Human Bloodstream Infections: Detection of MLSB Resistance

In this study we aimed to characterize antimicrobial resistance in methicillin-resistant Staphylococcus aureus (MRSA) isolated from bloodstream infections as well as the associated genetic lineages of the isolates. Sixteen MRSA isolates were recovered from bacteremia samples from inpatients between 2016 and 2019. The antimicrobial susceptibility of these isolates was tested by the Kirby–Bauer disk diffusion method against 14 antimicrobial agents. To determine the macrolide–lincosamide–streptogramin B (MLS_B) resistance phenotype of the isolates, erythromycin-resistant isolates were assessed by double-disk diffusion (D-test). The resistance and virulence genes were screened by polymerase chain reaction (PCR). All isolates were characterized by multilocus sequence typing (MLST), spa typing, staphylococcal chromosomal cassette mec (SCCmec) typing, and accessory gene regulator (agr) typing. Isolates showed resistance to cefoxitin, penicillin, ciprofloxacin, erythromycin, fusidic acid, clindamycin, and aminoglycosides, confirmed by the presence of the blaZ, ermA, ermC, mphC, msrA/B, aac(6’)-Ie-aph(2’’)-Ia, and ant(4’)-Ia genes. Three isolates were Panton–Valentine-leukocidin-positive. Most strains (n = 12) presented an inducible MLS_B phenotype. The isolates were ascribed to eight spa-types (t747, t002, t020, t1084, t008, t10682, t18526, and t1370) and four MLSTs (ST22, ST5, ST105, and ST8). Overall, most (n = 12) MRSA isolates had a multidrug-resistance profile with inducible MLS_B phenotypes and belonged to epidemic MRSA clones.

A Simple Protocol for the Stereoselective Construction of Enaminyl Sulfonyl Fluorides

A clickable connective hub 1-bromo-2-triazolethane-1-sulfonyl fluoride BTESF (1) was developed and successfully applied for the fluorosulfonylvinylation of a host of primary and secondary cyclic or acyclic amines including amino acids and pharmaceuticals. Further antimicrobial experiments revealed that vinyl sulfonyl fluoride functionalized norfloxacin (3ak), ciprofloxacin (3am), and lomefloxacin (3an) exhibited 4-fold improved antimicrobial activity against Gram-positive bacteria compared to their parent drugs.

Silver Nanoparticles at Biocompatible Dosage Synergistically Increases Bacterial Susceptibility to Antibiotics

Antibiotics used to treat bacterial infections can become ineffective over time or result in the emergence of antibiotic resistant pathogens. With the advent of nanotechnology, silver nanoparticles (AgNPs) have gained significant attention as a therapeutic agent due to the well-known antimicrobial properties of silver. However, there are concerns and limited literature on the potential cytotoxicity of nanoparticles at effective antimicrobial concentrations. AgNPs prepared from silver nitrate with glucose reduction were characterized by surface plasmon resonance, dynamic light scattering, zeta potential analysis and transmission electron microscopy. The cytotoxicity of AgNPs towards human gingival fibroblasts over 7 days was determined using cell proliferation assays and confocal microscopy. AgNP MIC and antibacterial effects alone and in combination with 11 antibiotics were determined against a panel of nine microbial species including gram-positive and gram-negative bacterial species. AgNPs concentrations ≤ 1 μg/mL were non-cytotoxic but also showed no antibacterial effects. However, when combined with each of eleven antibiotics, the biocompatible concentration of AgNPs (1 μg/mL) resulted in significant inhibition of bacterial growth for multiple bacterial species that were resistant to either the antibiotics or AgNPs alone. This study presents a promising strategy with further testing in vivo, to develop novel antimicrobial agents and strategies to confront emerging antimicrobial resistance.

Antibacterial activities and DNA-cleavage properties of novel fluorescent imidazo-phenanthroline derivatives

Design and biological activities of fluorescent imidazo-phenanthroline derivatives; (E)-5-((4-((4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)phenoxy)methyl)benzylidene)amino)- isophthalicacid, 2 and 2-(4-(((5-chloroquinolin-8-yl)oxy)methyl)phenyl)-1H-imidazo[4,5f] [1,10]phenanthroline, 3, have been reported. Their characterizations were performed by spectroscopic techniques. Their promising photophysical behaviours were observed in absorbance and fluorescence studies. The antibacterial activities of the compounds were determined against seven different microorganisms; Bacillus subtilis ATCC 6633(G + ), Pseudomonas aeruginosa ATCC 29853(G-), Escherichia coli ATCC 35,218 (G-), Enterococcus faecalis ATCC 292,112 (G + ), Salmonella typhimurium ST-10 (G-), Streptococcus mutans NCTC 10,449 (G + ), and Staphylococcus aureus ATCC 25923(G + ). MIC values of 3 was determined as 156,25 μM on all tested bacteria. A preliminary study of the structure-activity relationship (SAR) also revealed that the antimicrobial activity depended on the substituents on the phenyl ring. The electron withdrawing Cl-substitued compound 3 most favour for antimicrobial activity even at lowest concentration compared to other compounds. DNA-cleavage activities of the compounds were also investigated. The interactions of the compounds with supercoiled pBR322 plasmid DNA were obtained by agarose gel electrophoresis. All imidazo-phenanthroline derivatives were found to be highly effective on DNA, even at the lowest concentrations because of their planar nature which provides ease of bind to the helix structure of DNA.