Ethylenic conjugated coumarin thiazolidinediones as new efficient antimicrobial modulators against clinical methicillin-resistant Staphylococcus aureus

Medicinal Perspective of 2,4-Thiazolidinediones Derivatives: An Insight into Recent Advancements

2,4-Thiazolidinedione derivatives represent nitrogen-containing heterocyclic compounds utilized in type 2 diabetes mellitus management. Recent advances in medicinal chemistry have unveiled diverse therapeutic potentials and structural modifications of these derivatives. This review delves into novel TZD derivatives, encompassing their synthesis, structure-activity relationships, and pharmacokinetic profiles. Various therapeutic potentials of TZDs are explored, including anticancer, antimicrobial, anti-inflammatory, antioxidant, anticonvulsant, antihyperlipidemic, anticorrosive, and antitubercular activities. Additionally, it addresses mitigating side effects associated with marketed TZD derivatives such as weight gain, oedema, fractures, and congestive heart failure in type 2 diabetes mellitus management. The review elaborates on in vivo, in vitro, and ex vivo studies supporting different biological activities, alongside predicting ADME and drug-likeness properties of TZDs. Computational studies are also integrated to elucidate binding modes and affinities of novel TZD derivatives. Furthermore, a plethora of novel TZD derivatives with varied and enhanced therapeutic potentials are presented, warranting further evaluation of their biological activities.

Multitarget Pharmacology of Sulfur-Nitrogen Heterocycles: Anticancer and Antioxidant Perspectives

Cancer and oxidative stress are interrelated, with reactive oxygen species (ROS) playing crucial roles in physiological processes and oncogenesis. Excessive ROS levels can induce DNA damage, leading to cancer, and disrupt antioxidant defenses, contributing to diseases like diabetes and cardiovascular disorders. Antioxidant mechanisms include enzymes and small molecules that mitigate ROS damage. However, cancer cells often exploit oxidative conditions to evade apoptosis and promote tumor growth. Antioxidant therapy has shown mixed results, with timing and cancer-type influencing outcomes. Multifunctional drugs targeting multiple pathways offer a promising approach, reducing side effects and improving efficacy. Recent research focuses on sulfur-nitrogen heterocyclic derivatives for their dual antioxidant and anticancer properties, potentially enhancing therapeutic efficacy in oncology. The newly synthesized compounds often do not demonstrate both antioxidant and anticancer properties simultaneously. Heterocyclic rings are typically combined with phenyl groups, where hydroxy substitutions enhance antioxidant activity. On the other hand, electron-withdrawing substituents, particularly at the p-position on the phenyl ring, tend to enhance anticancer activity.

Unique aminothiazolyl coumarins as potential DNA and membrane disruptors towards Enterococcus faecalis

Aminothiazolyl coumarins as potentially new antimicrobial agents were designed and synthesized in an effort to overcome drug resistance. Biological activity assay revealed that some target compounds exhibited significantly inhibitory efficiencies toward bacteria and fungi including drug-resistant pathogens. Especially, aminothiazolyl 7-propyl coumarin 8b and 4-dichlorobenzyl derivative 11b exhibited bactericidal potential (MBC/MIC = 2) toward clinically drug-resistant Enterococcus faecalis with low cytotoxicity to human lung adenocarcinoma A549 cells, rapidly bactericidal effects and no obvious bacterial resistance development against E. faecalis. The preliminary antibacterial action mechanism studies suggested that compound 11b was able to disturb E. faecalis membrane effectively, and interact with bacterial DNA isolated from resistant E. faecalis through noncovalent bonds to cleave DNA, thus inhibiting the growth of E. faecalis strain. Further molecular modeling indicated that compounds 8b and 11b could bind with SER-1084 and ASP-1083 residues of gyrase-DNA complex through hydrogen bonds and hydrophobic interactions. Moreover, compound 11b showed low hemolysis and in vivo toxicity. These findings of aminothiazolyl coumarins as unique structural scaffolds might hold a large promise for the treatments of drug-resistant bacterial infection.

Hydrazyl hydroxycoumarins as new potential conquerors towards Pseudomonas aeruginosa

A class of unique hydrazyl hydroxycoumarins (HHs) as novel structural scaffold was developed to combat dreadful bacterial infections. Some HHs could effectively suppress bacterial growth at low concentrations, especially, pyridyl HH 7 exhibited a good inhibition against Pseudomonas aeruginosa 27853 with a low MIC value of 0.5 μg/mL, which was 8-fold more active than norfloxacin. Furthermore, pyridyl HH 7 with low hemolytic activity and low cytotoxicity towards NCM460 cells showed much lower trend to induce the drug-resistant development than norfloxacin. Preliminarily mechanism exploration indicated that pyridyl HH 7 could eradicate the integrity of bacterial membrane, result in the leakage of intracellular proteins, and interact with bacterial DNA gyrase via non-covalent binding, and ADME analysis manifested that compound 7 gave good pharmacokinetic properties. These results suggested that the newly developed hydrazyl hydroxycoumarins as potential multitargeting antibacterial agents should be worthy of further investigation for combating bacterial infection.

Discovery of indolylacryloyl-derived oxacins as novel potential broad-spectrum antibacterial candidates

The emergence of serious bacterial resistance towards clinical oxacins poses a considerable threat to global public health, necessitating the development of novel structural antibacterial agents. Seven types of novel indolylacryloyl-derived oxacins (IDOs) were designed and synthesized for the first time from commercial 3,4-difluoroaniline via an eight-step procedure. The synthesized compounds were characterized by modern spectroscopic techniques. All target molecules were evaluated for antimicrobial activities. Most of the prepared IDOs showed a broad antibacterial spectrum and strong activities against the tested strains, especially ethoxycarbonyl IDO 10d (0.25-0.5 μg/mL) and hydroxyethyl IDO 10e (0.25-1 μg/mL) exhibited much superior antibacterial efficacies to reference drug norfloxacin. These highly active IDOs also displayed low hemolysis, cytotoxicity and resistance, as well as rapid bactericidal capacity. Further investigations indicated that ethoxycarbonyl IDO 10d and hydroxyethyl IDO 10e could effectively reduce the exopolysaccharide content and eradicate the formed biofilm, which might delay the development of drug resistance. Preliminary exploration of the antibacterial mechanism revealed that active IDOs could not only destroy membrane integrity, resulting in changes in membrane permeability, but also promote the accumulation of reactive oxygen species, leading to the production of malondialdehyde and decreased bacterial metabolism. Moreover, they exhibited the capability to bind with DNA and DNA gyrase, forming supramolecular complexes through various noncovalent interactions, thereby inhibiting DNA replication and causing bacterial death. All the above results suggested that the newly developed indolylacryloyl-derived oxacins should hold great promise as potential multitargeting broad-spectrum antibacterial candidates to overcome drug resistance.

Isolating Antipathogenic Fungal Coumarins from Coriaria nepalensis and Determining Their Primary Mechanism In Vitro

Through bioassay-guided isolation, eight undescribed coumarins (1-8), along with six reported coumarins (9-14), were obtained from Coriaria nepalensis. The new structures were determined by using IR, UV, NMR, HRESIMS, and ECD calculations. The results of the biological activity assays showed that compound 9 exhibited broad spectrum antifungal activities against all tested fungi in vitro and a significant inhibitory effect on Phytophthora nicotianae with an EC50 value of 3.00 μg/mL. Notably, compound 9 demonstrated greater curative and protective effects against tobacco balack shank than those of osthol in vivo. Thus, 9 was structurally modified to obtain new promising antifungal agents, and the novel derivatives (17b, 17j, and 17k) exhibited better effects on Sclerotinia sclerotiorum than did lead compound 9. Preliminary mechanistic exploration illustrated that 9 could enhance cell membrane permeability, destroy the morphology and ultrastructure of cells, and reduce the exopolysaccharide content of P. nicotianae mycelia. Furthermore, the cytotoxicity results revealed that compound 9 exhibited relatively low cytotoxicity against HEK293 cell lines with an inhibition rate of 33.54% at 30 μg/mL. This research is promising for the discovery of new fungicides from natural coumarins with satisfactory ecological compatibility.

Synthetic Strategies of Thiazolidine-2,4-dione Derivatives for the Development of New Anti-diabetic Agents: Compressive Review

BACKGROUND

Thiazolidine-2,4-dione (2,4-TZD) is a flexible pharmacophore and a privileged platform and contains a five-membered ring with a 2-oxygen atom with double bond 2,4- position and one nitrogen atom as well as sulphur containing in the heterocyclic compound. A famous electron-rich nitrogen transporter combines invigorating electronic properties with the prospective for elemental applications. Thiazolidine-2,4-dione analogues have been synthesized using a variety of methods, all of which have shown to have a strong biological effect.

OBJECTIVES

The study of the biological activity of Thiazolidine-2,4-dione derivatives has been a fascinating field of pharmaceutical chemistry and has many purposes. This derivative described in the literature between 1995 to 2023 was the focus of this study. Thiazolidine-2,4-diones have been discussed in terms of their introduction, general method, synthetic scheme and antidiabetic significance in the current review.

CONCLUSION

Thiazolidine-2,4-diones are well-known heterocyclic compounds. The synthesis of Thiazolidine-2,4-diones has been described using a variety of methods. Antidiabetic activity has been discovered in several Thiazolidine-2,4-dione derivatives, which enhance further research. The use of Thiazolidine-2,4-diones to treat antidiabetics has piqued researchers' interest in learning more about thiazolidine-2,4-diones.

Thiazolidin-4-Ones as a Promising Scaffold in the Development of Antibiofilm Agents-A Review

Thiazolidin-4-ones have a broad range of medical and clinical implementation, which is important for pharmaceutical and medicinal chemistry. This heterocyclic core has been reported to possess a diversity of bioactivities, including antimicrobial and antibiofilm-forming potential. The resistance of biofilms to antibiotics or disinfectants is a serious medical problem. Therefore, there is a natural need to discover new effective structures with properties that inhibit biofilm formation. This review aims to analyze the antibiofilm features of thiazolidin-4-ones described in the literature over the last two decades. The information gathered in this review could benefit the rational design of new effective antibiofilm small molecules with thiazolidin-4-one cores.

Robust Optical Detection of Ga3+ by a Rhodamine- and Coumarin-Based Proficient Probe: Theoretical Investigations and Biological Applications

The present investigation highlights a rhodamine-B- and coumarin-based efficient probe that selectively detects Ga3+ over other metal ions. The active pocket of the ligand for trapping the metal ions and the binding stoichiometry of its Ga3+ complex were discovered by single-crystal X-ray diffraction (SC-XRD) analysis. This binding stoichiometry was further confirmed in the solution state by mass spectrometry and Job's plot. The detection limit was found to be at the nanomolar level. Pyrophosphate being a well-known quencher could easily quench the fluorescence intensity of the RC in the presence of Ga3+ and reversibly recognize Ga3+ in the solution. The spiro ring opening of the ligand after Ga3+ insertion is proposed to be the principal mechanism for the turn-on fluorescence response. This ring opening was confirmed by SC-XRD data and nuclear magnetic resonance (NMR) titration experiments. Both ground- and excited-state calculations of the ligand and complex have been carried out to obtain information about their energy levels and to obtain the theoretical electronic spectra. Furthermore, the live-cell imaging of the probe only and the probe after the addition of Ga3+ have been carried out in HaCaT cells and satisfactory responses were observed. Interestingly, with the help of this probe, Ga3+ can be tracked inside the intracellular organelle such as lysosomes along with other regions of the cell. The article highlights a rhodamine-coumarin-based probe for the detection of Ga3+ over other metal ions with a nanomolar level detection limit. Structural characterization of the ligand and its Ga3+ complex was investigated by SC-XRD. Density functional theory (DFT) and time-dependent DFT (TD-DFT) studies were carried out to explore the excited-state energies and electronic spectra. The application of the probe for the detection of Ga3+ in live cells has been explored, and positive responses were observed.

Benzopyrone-mediated quinolones as potential multitargeting antibacterial agents

A new type of benzopyrone-mediated quinolones (BMQs) was rationally designed and efficiently synthesized as novel potential antibacterial molecules to overcome the global increasingly serious drug resistance. Some synthesized BMQs effectively suppressed the growth of the tested strains, outperforming clinical drugs. Notably, ethylidene-derived BMQ 17a exhibited superior antibacterial potential with low MICs of 0.5-2 μg/mL to clinical drugs norfloxacin, it not only displayed rapid bactericidal performance and inhibited bacterial biofilm formation, but also showed low toxicity toward human red blood cells and normal MDA-kb2 cells. Mechanistic investigation demonstrated that BMQ 17a could effectually induce bacterial metabolic disorders and promote the enhancement of reactive oxygen species to disrupt the bacterial antioxidant defense system. It was found that the active molecule BMQ 17a could not only form supramolecular complex with lactate dehydrogenase, which disturbed the biological functions, but also effectively embed into calf thymus DNA, thus affecting the normal function of DNA and achieving cell death. This work would provide an insight into developing new molecules to reduce drug resistance and expand antibacterial spectrum.

Selective and Sensitive Detection of Hg2+ and Ag+ by a Fluorescent and Colorimetric Probe with Large Stokes Shift

Development of fluorescent sensors with large Stokes shift for selective detection of heavy metals is of great importance. A novel fluorescent probe with extremely large Stokes shift (212 nm) was synthesized for selective and simultaneous detection of Hg2+ and Ag+ ions. The deep yellow probe turned colorless or pale yellow after addition of Hg2+ or Ag+. The new probe could be utilized for absorption spectral detection of Hg2+ and Ag+ both in ethanol and aqueous solution. Addition of Hg2+ and Ag+ ions caused significant decrease in the fluorescence intensity of the new probe and the selective recognition of Hg2+ and Ag+ was not interfered by common competitive metal ions including Li+, Na+, K+, Cu2+, Fe2+, Zn2+, Co2+, Ni2+, Mn2+, Sr2+, Ca2+, Mg2+, Al3+, Cr3+ and Fe3+. The detection limit for Hg2+ and Ag+ was calculated to be 4.68 μM and 4.29 μM, respectively. Application of the new probe for quantitative determination of Hg2+ and Ag+ concentrations in real water samples was accomplished.

Novel Thiazolylketenyl Quinazolinones as Potential Anti-MRSA Agents and Allosteric Modulator for PBP2a

Bacterial infections caused by methicillin-resistant Staphylococcus aureus have seriously threatened public health. There is an urgent need to propose an existing regimen to overcome multidrug resistance of MRSA. A unique class of novel anti-MRSA thiazolylketenyl quinazolinones (TQs) and their analogs were developed. Some synthesized compounds showed good bacteriostatic potency. Especially TQ 4 was found to exhibit excellent inhibition against MRSA with a low MIC of 0.5 μg/mL, which was 8-fold more effective than norfloxacin. The combination of TQ 4 with cefdinir showed stronger antibacterial potency. Further investigation revealed that TQ 4, with low hemolytic toxicity and low drug resistance, was not only able to inhibit biofilm formation but also could reduce MRSA metabolic activity and showed good drug-likeness. Mechanistic explorations revealed that TQ 4 could cause leakage of proteins by disrupting membrane integrity and block DNA replication by intercalated DNA. Furthermore, the synergistic antibacterial effect with cefdinir might be attributed to TQ 4 with the ability to induce PBP2a allosteric regulation of MRSA and further trigger the opening of the active site to promote the binding of cefdinir to the active site, thus inhibiting the expression of PBP2a, thereby overcoming MRSA resistance and significantly enhancing the anti-MRSA activity of cefdinir. A new strategy provided by these findings was that TQ 4, possessing both excellent anti-MRSA activity and allosteric effect of PBP2a, merited further development as a novel class of antibacterial agents to overcome increasingly severe MRSA infections.

Thiazolyl hydrazineylidenyl indolones as unique potential multitargeting broad-spectrum antimicrobial agents

The emergence of pathogenic and drug-resistant microorganisms seriously threatens public safety. This work constructed a unique type of thiazolyl hydrazineylidenyl indolones (THIs) to combat global microbial multidrug-resistance. Bioactive evaluation discovered that some target THIs displayed much superior antimicrobial efficacy than clinical chloromycetin, norfloxacin, cefdinir or fluconazole against the tested strains. Eminently, butyl THI 6c displayed a broad antimicrobial spectrum with low MICs of 0.25-1 μg/mL. The highly active THI 6c not only showed low cytotoxicity and hemolysis, rapidly bactericidal ability, good antibiofilm activity and promising pharmacokinetic properties, but also could significantly impede the development of bacterial resistance. Preliminary exploration of antibacterial mechanism revealed that THI 6c could effectively penetrate the cell membrane of MRSA and embed DNA to form 6c‒DNA supramolecular complex and thus hinder DNA replication. Moreover, THI 6c could reduce cell metabolic activity, which might be attributed to the fact that THI 6c could target the pyruvate kinase of MRSA and interfere with the function of the enzyme. These results provided powerful information for further developing thiazolyl hydrazineylidenyl indolones as new broad-spectrum antimicrobial agents.

Comprehensive Insights into Medicinal Research on Imidazole-Based Supramolecular Complexes

The electron-rich five-membered aromatic aza-heterocyclic imidazole, which contains two nitrogen atoms, is an important functional fragment widely present in a large number of biomolecules and medicinal drugs; its unique structure is beneficial to easily bind with various inorganic or organic ions and molecules through noncovalent interactions to form a variety of supramolecular complexes with broad medicinal potential, which is being paid an increasing amount of attention regarding more and more contributions to imidazole-based supramolecular complexes for possible medicinal application. This work gives systematical and comprehensive insights into medicinal research on imidazole-based supramolecular complexes, including anticancer, antibacterial, antifungal, antiparasitic, antidiabetic, antihypertensive, and anti-inflammatory aspects as well as ion receptors, imaging agents, and pathologic probes. The new trend of the foreseeable research in the near future toward imidazole-based supramolecular medicinal chemistry is also prospected. It is hoped that this work provides beneficial help for the rational design of imidazole-based drug molecules and supramolecular medicinal agents and more effective diagnostic agents and pathological probes.

Photobiological effect of eugenol-derived 3-benzoylcoumarin associated with led lights against MDR microorganisms

The problem of antibiotic resistance by bacteria threatens human health. Therefore, studies in this area seek alternatives to circumvent it. The study with coumarins and eugenol has already proven that these classes of compounds act against bacteria. In this same aspect, exposure to LED also shows a bactericidal effect. Seeking a possible enhancement of this effect, the present work studied coumarins derived from eugenol in association with LED to investigate the bactericidal effect. Four compounds were tested. For this, minimum inhibitory concentrations (MICs) and modulation with three antibiotics against Escherichia coli and Staphylococcus aureus bacteria were determined. To test the behavior of the activity against exposure to LED, the plates were exposed for 20 min to blue light, 415 nm and then incubated at 37°C for 24 h. For control, duplicates were made, and one of them did not undergo this exposure. C1 exhibited better activity against S. aureus, as synergism prevailed under the conditions tested. C3 and C4 were promising against E. coli as they showed synergism in association with the three antibiotics both with and without LED exposure. Thus, the compounds showed bactericidal activity, and LED was shown to enhance synergism.

Synthesis and Biological Evaluation of Piperazine Hybridized Coumarin Indolylcyanoenones with Antibacterial Potential

A class of piperazine hybridized coumarin indolylcyanoenones was exploited as new structural antibacterial frameworks to combat intractable bacterial resistance. Bioactive assessment discovered that 4-chlorobenzyl derivative 11f showed a prominent inhibition on Pseudomonas aeruginosa ATCC 27853 with a low MIC of 1 μg/mL, which was four-fold more effective than norfloxacin. Importantly, the highly active 11f with inconspicuous hemolysis towards human red blood cells displayed quite low proneness to trigger bacterial resistance. Preliminary explorations on its antibacterial behavior disclosed that 11f possessed the ability to destroy bacterial cell membrane, leading to increased permeability of inner and outer membranes, the depolarization and fracture of membrane, and the effusion of intracellular components. Furthermore, bacterial oxidative stress and metabolic turbulence aroused by 11f also accelerated bacterial apoptosis. In particular, 11f could not only effectively inset into DNA, but also bind with DNA gyrase through forming supramolecular complex, thereby affecting the biological function of DNA. The above findings of new piperazine hybridized coumarin indolylcyanoenones provided an inspired possibility for the treatment of resistant bacterial infections.

In vitro and in silico antibacterial evaluation of coumarin derivatives against MDR strains of Staphylococcus aureus and Escherichia coli

The increase in antibiotic resistance rates has attracted the interest of researchers for antibacterial compounds capable of potentiating the activity of conventional antibiotics. Coumarin derivatives have been reported to develop effective antibacterials with possible new mechanisms of action for treating infectious diseases caused by bacteria with a profile of drug resistance. In this context, the aim of the present study we have now prepared one variety of new synthetic coumarins evaluating the pharmacokinetic and chemical similarity in silico, their antimicrobial activity against Staphylococcus aureus (ATCC 25923) and Escherichia coli (ATCC 25922), and potential for the modulation of antibiotic resistance against Staphylococcus aureus (SA10) and Escherichia coli (EC06) clinical isolate bacteria by in vitro assay. The antibacterial activity and antibiotic-enhancing properties were evaluated by the broth microdilution method and pharmacokinetically characterized according to the Lipinsk rule of 5 and had their similarity analyzed in databases such as ChemBL and CAS SciFinder. The results demonstrated that only compound C13 showed significant antibacterial activity (MIC ≤256 μg/mL), and all other coumarins did not display relevant antibacterial activity (MIC ≥1024 μg/mL). However, they did modulate the antibiotics activities to norfloxacin and gentamicin, except, compound C11 to norfloxacin against Staphylococcus aureus (SA10). The in silico properties prediction and drug-likeness results demonstrated that all coumarins presented a good drug-likeness score with no violations and promising in silico pharmacokinetic profiles showing that they have the potential to be developed into an oral drug. The results indicate that the coumarin derivatives showed good in vitro antibacterial activity. These new coumarin derivatives also demonstrated the capacity to modulate antibiotic resistance with potential synergy action for current antimicrobials assayed, as antibiotic adjuvants, to reduce the emergence of antimicrobial resistance.

New Efforts toward Aminothiazolylquinolones with Multitargeting Antibacterial Potential

New antibacterial 3-(aminothiazolyl)quinolones (ATQs) were designed and efficiently synthesized to counteract the growing multidrug resistance in animal husbandry. Bioactive assays manifested that N,N-dicyclohexylaminocarbonyl ATQ 10e and methyl ATQ 17a, respectively, showed better antibacterial behavior against Staphylococcus aureus ATCC 29213 and Pseudomonas aeruginosa than reference drug norfloxacin. Notably, highly active ATQ 17a with low hemolysis, negligible mammalian cytotoxicity, and good pharmacokinetic properties displayed low trends to induce resistance and synergistic combinations with norfloxacin. Preliminary mechanism exploration implied that representative ATQ 17a could inhibit the formation of biofilms and destroy bacterial membrane integrity, further binding to intracellular DNA and DNA gyrase to hinder bacterial DNA replication. ATQ 17a could also induce the production of excess reactive oxygen species and reduce bacterial metabolism to accelerate bacterial death. These results provided a promise for 3-(aminothiazolyl)quinolones as new potential multitargeting antibacterial agents to treat bacterial infection of animals.

An unanticipated discovery of novel naphthalimidopropanediols as potential broad-spectrum antibacterial members

Constructing a new antibacterial structural framework is an effective strategy to combat drug resistance. This work discovered a class of naphthalimidopropanediols (NIOLs) as a novel structural type of potential broad-spectrum antibacterial agents. Especially, NIOLs 9u, 12i, 15 against Staphylococcus aureus and NIOLs 9l, 13a against Pseudomonas aeruginosa showed excellent inhibitory activities, and they displayed high membrane selectivity from an electrostatic distinction on the membranes between bacteria and mammalian cells. These highly active NIOLs could effectually inhibit the bacterial growths, and relieve the resistance developments. Moreover, the facts of membrane depolarization, outer/inner membrane permeabilization and leakage of intracellular materials, demonstrated that these NIOLs could target and destroy the S. aureus or P. aeruginosa membranes. In particular, they could disrupt the antioxidant defense systems of S. aureus or P. aeruginosa through up-regulation of reactive oxygen species. Simultaneously, they could render the metabolic inactivation of the tested strains, and eradicate the formed biofilms and efficiently kill the strains within the biofilms. The in vitro and in vivo cytotoxicity assay indicated that these compounds possessed low toxicity. These findings of novel NIOLs as potential broad-spectrum antibacterial members provided a bright hope for conquering drug resistance.

Site-Specific Evaluation of Bioactive Coumarin-Loaded Dendrimer G4 Nanoparticles against Methicillin Resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is a foremost treatment challenge in today's clinical practice. Natural coumarins contain a variety of bioactivities and have the ability to alter resistance in several ways. In developing effective drug delivery methods, the goal is to maximize biocompatibility while minimizing toxicity. With this in mind, this work investigated the site-specific potential of dendrimer G4 poloxamer nanoparticles loaded with bioactive coumarin. The goal of the current work is to deliver a complete evaluation of dendrimer G4 poloxamer nanoparticles against MRSA. Coumarin-loaded dendrimer G4 poloxamer nanoparticles were thoroughly investigated and characterized using various techniques, including particle size, shape, entrapment efficiency, in vitro drug release, hemolysis assay, cytotoxicity, antibacterial activity, and bactericidal kinetics. Studies showed that the newly developed dendrimer G4 poloxamer nanoparticles exhibited significantly lower levels of hemolysis and cytotoxicity. The results showed that the in vitro drug release of coumarin from dendrimer G4 poloxamer nanoparticles was slower compared to coumarin in its free form. This innovative therapeutic delivery technology may enhance the defense of coumarin against MRSA.

Coumarin-Encapsulated Solid Lipid Nanoparticles as an Effective Therapy against Methicillin-Resistant Staphylococcus aureus

Bacterial infections caused by antibiotic-resistant pathogens are a significant public health problem. This is because the transmission of infectious diseases is shifting, and new antibiotic-resistant strains of bacteria are emerging. The development of biofilms that are resistant to antibiotics poses another hurdle to drugs and treatment alternatives. Therefore, there is an urgent need to develop innovative strategies to effectively eliminate antibiotic-resistant microorganisms effectively. Natural coumarins have broad spectrum bioactivity and the potential for lower resistance. Coumarin is a secondary metabolite found in certain plants, fungi, and bacteria. It is highly effective against methicillin-resistant Staphylococcus aureus (MRSA). Therefore, coumarin can be used as an alternative to combat MRSA. However, most antibacterial agents lack selective targeting of pathological sites, limiting the efficacy of their antibacterial activity. Efficient MRSA treatments can be achieved through nanoparticle (NPs)-based targeted therapies. To address this challenge, a novel coumarin-loaded solid lipid nanocarrier for MRSA was developed to overcome this challenge. The developed systems exhibited a particle size of 138.5 ± 76.06 nm and a polydispersity index (PDI) of 0.245 ± 0.00. The zeta potential of coumarin-loaded SLNs was reported to be -22.2 ± 8.15 mV with a spherical shape. The encapsulation efficiency of coumarin was reported to be 63.09 ± 3.46% in the final formulation. The developed formulation was biocompatible with a minimum inhibitory concentration (MIC) of 1.08 µg/mL. This study suggests that coumarin-loaded SLNs can effectively treat MRSA infections.

Aloe emodin-conjugated sulfonyl hydrazones as novel type of antibacterial modulators against S. aureus 25923 through multifaceted synergistic effects

Aloe emodin-conjugated sulfonyl hydrazones were designed and synthesized as novel type of antibacterial modulators. Aloe emodin benzenesulfonyl hydrazone 5a (AEBH-5a) was preponderant for the treatment of S. aureus 25923 (MIC = 0.5 μg/mL) over norfloxacin and presented high selectivity between bacterial membranes and mammalian membranes. Especially, AEBH-5a could eliminate the formed biofilms and relieve the development of S. aureus 25923 resistance. The antibacterial mechanism of AEBH-5a from extracellularity to intracellularity illustrated that AEBH-5a could destroy bacterial membrane integrity, leading to the leakage of protein and nucleic acid. Besides, AEBH-5a could not only interact with DNA and induce oxidative stress but also inhibit lactate dehydrogenase (LDH) activity as well as render metabolic inactivation. In silico ADME studies prediction of AEBH-5a revealed a favorable bioavailability score and prominent drug-likeness profile. This research showed that the multifaceted synergistic effect initiated by aloe emodin-conjugated sulfonyl hydrazones is a reasonable and effective tactic to combat menacing bacterial infections.

Pyrimidine-conjugated fluoroquinolones as new potential broad-spectrum antibacterial agents

Pyrimidine-conjugated fluoroquinolones were constructed to cope with the dreadful resistance. Most of the target pyrimidine derivatives effectively suppressed the growth of the tested strains, especially, 4-aminopyrimidinyl compound 1c showed a broad antibacterial spectrum and low cytotoxicity and exhibited superior antibacterial potency against Enterococcus faecalis with a low MIC of 0.25 μg/mL to norfloxacin and ciprofloxacin. The active compound 1c with fast bactericidal potency could inhibit the formation of biofilms and showed much lower trend for the development of drug-resistance than norfloxacin and ciprofloxacin. Further exploration revealed that compound 1c could prompt ROS accumulations in bacterial cells and interact with DNA to form a DNA-1c complex, thus facilitating bacterial death. ADME analysis indicated that compound 1c possessed favorable drug-likeness and promising pharmacokinetic properties. These results demonstrated that pyrimidine-conjugated fluoroquinolones held hope as potential antibacterial candidates and deserve further study.

A new exploration toward adamantane derivatives as potential anti-MDR agents: Design, synthesis, antimicrobial, and radiosterilization activity as potential topoisomerase IV and DNA gyrase inhibitors

Developing novel antimicrobial agents has become a necessitate due to the increasing rate of microbial resistance to antibiotics. All the newly adamantane derivatives were evaluated for their antimicrobial activities against six MDR clinical pathogenic isolates. The results exhibited that 13 compounds have from potent to good activity. Among those, five derivatives (6, 7, 9, 14a, and 14b) displayed the potent activities against the different isolates tested (MIC < 0.25 µg/ml with bacteria and <8 µg/ml with fungi) compared with Ciprofloxacin (CIP) and Fluconazole (FCA). Additionally, the potent adamantanes showed bactericidal and fungicidal effects based on (MBCs and MFCs) and the time-kill assay. The most active adamantane derivatives 7 and 14b exhibited a synergistic effect of ΣFIC ≤ 0.5 with CIP and FCA against the bacterial and fungal isolates. Moreover, no antagonistic effect appeared for the tested derivatives. Additionally, the interaction of DNA gyrase and topoisomerase IV enzymes with the compounds 6, 7, 9, 14a, and 14b exhibited potent antimicrobial activity using in vitro biochemical assays and gel-based DNA-supercoiling inhibition method. The activity of DNA gyrase and topoisomerase IV enzymes showed inhibitory activity (IC₅₀ ) of 6.20 µM and 9.40 µM with compound 7 and 10.14 µM and 13.28 µM with compound 14b, respectively. Surprisingly, exposing compound 7 to gamma irradiation sterilized and increased its activity. Finally, the in-silico analysis predicted that the most active derivatives had good drug-likeness and safe properties. Besides, molecular docking and quantum chemical studies revealed several important interactions inside the active sites and showed the structural features necessary for activity.

The medicinal perspective of 2,4-thiazolidinediones based ligands as antimicrobial, antitumor and antidiabetic agents: A review

2,4-Thiazolidinedione (2,4-TZD), commonly known as glitazone, is a ubiquitous heterocyclic pharmacophore possessing a plethora of pharmacological activities and offering a vast opportunity for structural modification. The diverse range of biological activities endowed with a novel mode of action, low cost, and easy synthesis has attracted the attention of medicinal chemists. Several researchers have integrated the TZD core with different structural fragments to develop a wide range of lead molecules against various clinical disorders. The most common sites for structural modifications at the 2,4-TZD nucleus are the N-3 and the active methylene at C-5. The review covers the recent development of TZD derivatives such as antimicrobial, anticancer, and antidiabetic agents. Various 2,4-TZD based agents or drugs, which are either under clinical development or in the market, are discussed in the study. Different synthetic methodologies for synthesizing the 2,4-TZD core are also included in the manuscript. The importance of various substitutions at N-3 and C-5 and the mechanisms of action and structure-activity relationships are also discussed. We hope this study will serve as a valuable tool for the scientific community engaged in the structural exploitation of the 2,4-TZD core for developing novel drug m\olecules for life-threatening ailments.

Discovery of novel phenylhydrazone-based oxindole-thiolazoles as potent antibacterial agents toward Pseudomonas aeruginosa

With the soaring of bacterial infection and drug resistance, it is imperative to exploit new efficient antibacterial agents. This work constructed a series of unique phenylhydrazone-based oxindole-thiolazoles to combat monstrous bacterial resistance. Some target molecules showed potent antibacterial activity, among which oxindole-thiolimidazole derived carboxyphenylhydrazone 4e exhibited an 8-fold stronger inhibitory ability than norfloxacin on the growth of P. aeruginosa, with MIC value of 1 μg/mL. Compound 4e with imperceptible hemolysis could hamper bacterial biofilm formation and significantly impede the development of bacterial resistance. Subsequent mechanism studies demonstrated that 4e could destruct bacterial cytoplasmic membrane, causing the leakage of cellular contents (protein and nucleic acid). Moreover, metabolic stagnation and intracellular oxidative stress caused by 4e expedited the death of bacteria. Furthermore, molecule 4e existed supramolecular interactions with DNA to block DNA proliferation. These research results provided a promising light for phenylhydrazone-based oxindole-thiolazoles as novel potential antibacterial agents.

Natural aloe emodin-hybridized sulfonamide aminophosphates as novel potential membrane-perturbing and DNA-intercalating agents against Enterococcus faecalis

The dramatic rise in drug resistance accelerated the desire for new antibacterial agents to safeguard human health. This work constructed a novel type of aloe emodin-hybridized sulfonamide aminophosphates as unique potential antibacterial agents. The biological assay revealed that some target hybrids possessed potent inhibitory activity. Particularly, ethyl aminophosphate-hybridized sulfadiazine aloe emodin 7a (EASA-7a) not only displayed preponderant antibacterial efficiency against drug-resistant E. faecalis at low concentration as 0.25 μg/mL but also possessed strong bacteriostatic capacity and low propensity to develop resistance toward E. faecalis. The weak hemolysis toward human red blood cells and efficient biofilm-disruptive ability further implied the therapeutic potential of EASA-7a. Preliminary studies disclosed that the excellent antibacterial behavior of EASA-7a might be attributed to its capacity to permeate and depolarize the bacterial membrane, as well as promote ROS accumulation and intercalate with DNA. These findings manifested that EASA-7a was worthy of further development to combat life-threatening bacterial infections.

Unique Carbazole-Oxadiazole Derivatives as New Potential Antibiotics for Combating Gram-Positive and -Negative Bacteria

Novel carbazole-oxadiazoles were developed as new potential antibacterial agents to combat dreadful resistance. Some target compounds displayed predominant inhibitory effects on the tested Gram-positive and -negative bacteria, and carbazole-oxadiazoles 5g, 5i-k, 16a-c, and tetrazole analogues 23b-c were found to be efficient in impeding the growth of MRSA and Pseudomonas aeruginosa ATCC 27853 (MICs = 0.25-4 μg/mL). Furthermore, compounds 5g and 23b-c not only possessed rapid bactericidal ability and low tendency to develop resistance but also exhibited low cytotoxic effects toward Hek 293T, HeLa, and red blood cells (RBCs), especially molecule 5g also showed low toxicity in vivo, which showed the therapeutic potential of these compounds. Further exploration indicated that compounds 5g, 5i, and 23b-c could disintegrate the integrity of bacterial cell membranes to leak the cytoplasmic contents, thus exerting excellent antibacterial effects. These facts mean that carbazole-based antibacterial agents might have bright prospects in confronting bacterial infections.

Recent Developments of Coumarin-based Hybrids in Drug Discovery

Coumarin scaffold is a highly significant O-heterocycle, namely benzopyran-2-ones, form an elite class of naturally occurring compounds that possess promising therapeutic perspectives. Based on its broad spectrum of biological activities, the privileged coumarin scaffold is applied to medicinal and pharmacological treatments by several rational design strategies and approaches. Structure-activity relationships of the coumarin-based hybrids with various bioactivity fragments revealed significant information toward the further development of highly potent and selective disorder therapeutic agents. The molecular docking studies between coumarins and critical therapeutic enzymes demonstrated mode of action by forming noncovalent interactions with more than one receptor, further rationally confirm information about structure-activity relationships. This review summarizes recent developments relating to coumarin-based hybrids with other pharmacophores aiming to numerous feasible therapeutic enzymatic targets to combat various therapeutic fields, including anticancer, antimicrobic, anti-Alzheimer, anti-inflammatory activities.

An unanticipated discovery towards novel naphthalimide corbelled aminothiazoximes as potential anti-MRSA agents and allosteric modulators for PBP2a

Available therapeutic strategies are urgently needed to conquer multidrug resistance of MRSA. A visible effort was guided towards the advancement of novel antibacterial framework of naphthalimide corbelled aminothiazoximes, and desired to assert some insight on the conjunction of individual pharmacophore with distinct biological activities and unique action mechanism. Preliminary assessment displayed that dimethylenediamine derivative 13d presented a wonderful inhibition on MRSA (MIC = 0.5 μg/mL), and showed excellent membrane selectivity (HC₅₀ > 200 μg/mL) from an electrostatic distinction of the electronegative bacterial membranes and the electroneutral mammalian membranes. Moreover, 13d could effectually relieve the development of MRSA resistance. Investigations into explaining the mechanism of anti-MRSA disclosed that 13d displayed strong lipase affinity, which facilitated its permeation into cell membrane, causing membrane depolarization, leakage of cytoplasmic contents and lactate dehydrogenase (LDH) inhibition. Meanwhile, 13d could exert interaction with DNA to hinder biological function of DNA, and disrupt the antioxidant defense system of MRSA through up-regulation of ROS subjected the strain to oxidative stress. In particular, the unanticipated mechanism for naphthalimide corbelled aminothiazoximes that 13d could suppress the expression of PBP2a by inducing allosteric modulation of PBP2a and triggering the open of the active site, was discovered for the first time. These findings of naphthalimide corbelled aminothiazoximes as a small-molecule class of anti-MRSA agents held promise in strategies for treatment of MRSA infections.

Identification of a novel antifungal backbone of naphthalimide thiazoles with synergistic potential for chemical and dynamic treatment

Aim: The high incidence and prevalence of fungal infections call for new antifungal drugs. This work was to develop naphthalimide thiazoles as potential antifungal agents. Results & methodology: These compounds showed significant antifungal potency toward some tested fungi. Especially, naphthalimide thiazole 4h with excellent anti-Candida tropicalis efficacy possessed good hemolysis level, low toxicity and no obvious resistance. Deciphering the mechanism showed that 4h interacted with DNA and disrupted the antioxidant defense system of C. tropicalis. Compound 4h also triggered membrane depolarization, leakage of cytoplasmic contents and LDH inhibition. Simultaneously, 4h rendered metabolic inactivation and eradicated the formed biofilms of C. tropicalis. Conclusion: The multifaceted synergistic effect initiated by naphthalimide thiazoles is a reasonable treatment window for prospective development.

Antibacterial Activity of Medicinal Plants and Their Constituents in the Context of Skin and Wound Infections, Considering European Legislation and Folk Medicine-A Review

Bacterial infections of skin and wounds may seriously decrease the quality of life and even cause death in some patients. One of the largest concerns in their treatment is the growing antimicrobial resistance of bacterial infectious agents and the spread of resistant strains not only in the hospitals but also in the community. This trend encourages researchers to seek for new effective and safe therapeutical agents. The pharmaceutical industry, focusing mainly on libraries of synthetic compounds as a drug discovery source, is often failing in the battle with bacteria. In contrast, many of the natural compounds, and/or the whole and complex plants extracts, are effective in this field, inactivating the resistant bacterial strains or decreasing their virulence. Natural products act comprehensively; many of them have not only antibacterial, but also anti-inflammatory effects and may support tissue regeneration and wound healing. The European legislative is in the field of natural products medicinal use formed by European Medicines Agency (EMA), based on the scientific work of its Committee on Herbal Medicinal Products (HMPC). HMPC establishes EU monographs covering the therapeutic uses and safe conditions for herbal substances and preparations, mostly based on folk medicine, but including data from scientific research. In this review, the medicinal plants and their active constituents recommended by EMA for skin disorders are discussed in terms of their antibacterial effect. The source of information about these plant products in the review is represented by research articles listed in scientific databases (Science Direct, PubMed, Scopus, Web of Science, etc.) published in recent years.

A facile reaction to access novel structural sulfonyl-hybridized imidazolyl ethanols as potential DNA-targeting antibacterial agents

A novel type of sulfonyl-hybridized imidazolyl ethanols as potential DNA-targeting antibacterial agents was constructed via the unique ring-opened reaction of oxiranes by imidazoles for the first time. Some developed target hybrids showed potential antimicrobial potency against the tested microbes. Especially, imidazole derivative 5f could strongly suppressed the growth of MRSA (MIC = 4 μg/mL), which was 2-fold and 16-fold more potent than the positive control sulfathiazole and norfloxacin. This compound exhibited quite low propensity to induce bacterial resistance. Antibacterial mechanism exploration indicated that compound 5f could embed in MRSA DNA to form steady 5f-DNA complex, which possibly hinder DNA replication to exert antimicrobial behavior. Molecular docking showed that molecule 5f could bind with dihydrofolate synthetase through hydrogen bonds. These results implied that imidazole derivative 5f could be served as a promising molecule for the exploration of novel antibacterial candidates.

Potential antibacterial ethanol-bridged purine azole hybrids as dual-targeting inhibitors of MRSA

A new class of antibacterial ethanol-bridged purine azole hybrids as potential dual-targeting inhibitors was developed. Bioactivity evaluation showed that some of the target compounds had prominent antibacterial activity against the tested bacteria, notably, metronidazole hybrid 3a displayed significant inhibitory activity against MRSA (MIC = 6 μM), and had no obvious toxicity on normal mammalian cells (RAW 264.7). In addition, compound 3a also did not induce drug resistance of MRSA obviously, even after fifteen passages. Molecular modeling studies showed that the highly active molecule 3a could insert into the base pairs of topoisomerase IA-DNA as well as topoisomerase IV-DNA through hydrogen bonding. Furthermore, a preliminary study on the antibacterial mechanism revealed that the active molecule 3a could rupture the bacterial membrane of MRSA and insert into MRSA DNA to block its replication, thus possibly exhibiting strong antibacterial activity. These results strongly indicated that the highly active hybrid 3a could be used as a potential dual-targeting inhibitor of MRSA for further development of valuable antimicrobials.

Novel chalcone-conjugated, multi-flexible end-group coumarin thiazole hybrids as potential antibacterial repressors against methicillin-resistant Staphylococcus aureus

The increasing resistance of methicillin-resistant Staphylococcus aureus (MRSA) to antibiotics has led to a growing effort to design and synthesize novel structural candidates of chalcone-conjugated, multi-flexible end-group coumarin thiazole hybrids with outstanding bacteriostatic potential. Bioactivity screening showed that hybrid 5i, which was modified with methoxybenzene, exerted a significant inhibitory activity against MRSA (MIC = 0.004 mM), which was 6 times better than the anti-MRSA activity of the reference drug norfloxacin (MIC = 0.025 mM). Compound 5i neither conferred apparent resistance onto MRSA strains even after multiple passages nor triggered evident toxicity to human hepatocyte LO2 cells and normal mammalian cells (RAW 264.7). Molecular docking showed that highly active molecule 5i might bind to DNA gyrase by forming stable hydrogen bonds. In addition, molecular electrostatic potential surfaces were developed to explain the high antibacterial activity of the target compounds. Furthermore, preliminary mechanism studies suggested that hybrid 5i could disrupt the bacterial membrane of MRSA and insert itself into MRSA DNA to impede its replication, thus possibly becoming a potential antibacterial repressor against MRSA.

Molecular design and preparation of 2-aminothiazole sulfanilamide oximes as membrane active antibacterial agents for drug resistant Acinetobacter baumannii

A series of 2-aminothiazole sulfanilamide oximes were developed as new membrane active antibacterial agents to conquer the microbial infection. Benzoyl derivative 10c was preponderant for the treatment of drug-resistant A. baumannii infection in contrast to norfloxacin and exerted excellent biocompatibility against mammalian cells including erythrocyte and LO2 cell line. Meanwhile, it had ability to eradicate established biofilm to alleviate the resistance burden. Mechanism investigation elucidated that compound 10c was able to disturb the membrane effectively and inhibit lactic dehydrogenase, which led to cytoplasmic content leakage. The cellular redox homeostasis was interfered via the production of reactive oxygen and nitrogen species (RONS), which further contributed to respiratory pathway inactivation and reduction of GSH activity. This work indicated that 2-aminothiazole sulfanilamide oximes could be a promising start for the exploitation of novel antibacterial agents against pathogens.

Novel carbazole-oxadiazoles as potential Staphylococcus aureus germicides

Staphylococcus aureus resistance poses nonnegligible threats to the livestock industry. In light of this, carbazole-oxadiazoles were designed and synthesized for treating S. aureus infection. Bioassay discovered that 3,6-dibromocarbazole derivative 13a had effective inhibitory activities to several Gram-positive bacteria, in particular to S. aureus, S. aureus ATCC 29213, MRSA and S. aureus ATCC 25923 (MICs = 0.6-4.6 nmol/mL), which was more active than norfloxacin (MICs = 6-40 nmol/mL). Subsequent studies showed that 3,6-dibromocarbazole derivative 13a acted rapidly on S. aureus ATCC 29213 and possessed no obvious tendency to induce bacterial resistance. Further evaluations indicated that 3,6-dibromocarbazole derivative 13a showed strong abilities to disrupt bacterial biofilm and interfere with DNA, which might be the power sources of antibacterial performances. Moreover, 3,6-dibromocarbazole derivative 13a also exhibited slight cell lethality toward Hek 293 T and LO2 cells and low hemolytic toxicity to red blood cells. The above results implied that the active molecule 13a could be studied in the future development of agricultural available antibiotics.

Discovery of novel purinylthiazolylethanone derivatives as anti-Candida albicans agents through possible multifaceted mechanisms

An unprecedented amount of fungal and fungal-like infections has recently brought about some of the most severe die-offs and extinctions due to fungal drug resistance. Aimed to alleviate the situation, new effort was made to develop novel purinylthiazolylethanone derivatives, which were expected to combat the fungal drug resistance. Some prepared purinylthiazolylethanone derivatives possessed satisfactory inhibitory action towards the tested fungi, among which compound 8c gave a MIC value of 1 μg/mL against C. albicans. The active molecule 8c was able to kill C. albicans with undetectable resistance as well as low hematotoxicity and cytotoxicity. Furthermore, it could hinder the growth of C. albicans biofilm, thus avoiding the occurrence of drug resistance. Mechanism research manifested that purinylthiazolylethanone derivative 8c led to damage of cell wall and membrane disruption, so protein leakage and the cytoplasmic membrane depolarization were observed. On this account, the activity of fungal lactate dehydrogenase was reduced and metabolism was impeded. Meanwhile, the increased levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) disordered redox equilibrium, giving rise to oxidative damage to fungal cells and fungicidal effect.

Identification of Unique Quinazolone Thiazoles as Novel Structural Scaffolds for Potential Gram-Negative Bacterial Conquerors

A class of quinazolone thiazoles was identified as new structural scaffolds for potential antibacterial conquerors to tackle dreadful resistance. Some prepared compounds exhibited favorable bacteriostatic efficiencies on tested bacteria, and the most representative 5j featuring the 4-trifluoromethylphenyl group possessed superior performances against Escherichia coli and Pseudomonas aeruginosa to norfloxacin. Further studies revealed that 5j with inappreciable hemolysis could hinder the formation of bacterial biofilms and trigger reactive oxygen species generation, which could take responsibility for emerging low resistance. Subsequent paralleled exploration discovered that 5j not only disintegrated outer and inner membranes to induce leakage of cytoplasmic contents but also broke the metabolism by suppressing dehydrogenase. Meanwhile, derivative 5j could intercalate into DNA to exert powerful antibacterial properties. Moreover, compound 5j gave synergistic effects against some Gram-negative bacteria in combination with norfloxacin. These findings indicated that this novel structural type of quinazolone thiazoles showed therapeutic foreground in struggling with Gram-negative bacterial infections.

Pyrimidinetrione-imidazoles as a Unique Structural Type of Potential Agents towards Candida Albicans: Design, Synthesis and Biological Evaluation

Substantial morbidity and mortality of fungal infections have aroused concerns all over the world, and common Candida spp. currently bring about severe systemic infections. A series of pyrimidinetrione-imidazole conjugates as potentially antifungal agents were developed. Bioassays manifested that 4-fluobenzyl pyrimidinetrione imidazole 5 f exerted favorable inhibition towards C. albicans (MIC=0.002 mM), being 6.5 folds more active than clinical antifungal drug fluconazole (MIC=0.013 mM). Preliminary mechanism research indicated that compound 5 f could not only depolarize membrane potential but also permeabilize the membrane of C. albicans. Molecular docking was operated to simulate the interaction mode between molecule 5 f and CYP51. In addition, hybrid 5 f might form 5 f-DNA supramolecular complex via intercalating into DNA. The interference of membrane and DNA might contribute to its fungicidal capacity with no obvious tendency to induce the resistance against C. albicans. Conjugate 5 f endowed good blood compatibility as well as low cytotoxicity towards HeLa and HEK-293T cells.

Design and synthesis of a new tripod-chromogenic sensor based on a s-triazine and thiazolidine-2,4-dione ring (TCST) for naked-eye detection of Li+

A novel tripod-chromogenic sensor based on a s-triazine and thiazolidine-2,4-dione ring (TCST) was designed, synthesized, and applied as a colorimetric probe in aqueous solutions of dimethyl sulfoxide (DMSO). The probe showed a highly sensitive and selective colorimetric sensor for naked-eye detection of Li+, changing from colourless to yellow. The probe’s detection limit toward Li+ was found to be 1.2 μM. The result of the Job plot analysis showed 1:1 stoichiometry for the interaction between the tripod chemosensor and Li+ and this result was confirmed by 1H NMR titration experiments. The probe can also be used for biological activities depending on the results of microbial tests.

Aloe-emodin derived azoles as a new structural type of potential antibacterial agents: design, synthesis, and evaluation of the action on membrane, DNA, and MRSA DNA isomerase

As serious global drug resistance motivated the exploration of new structural drugs, we developed a type of novel structural aloe-emodin azoles as potential antibacterial agents in this work. Some target aloe-emodin azoles displayed effective activity against the tested strains, especially tetrazolyl aloe-emodin 4b showed a low MIC value of 2 μg mL-1 towards MRSA, being more efficient than the reference drug norfloxacin (MIC = 8 μg mL-1). Also, the active molecule 4b exhibited low cytotoxicity against LO2 cells with no distinct tendency to induce the concerned resistance towards MRSA. The tetrazolyl derivative 4b was preliminarily investigated for the possible mechanism; it was revealed that tetrazolyl derivative 4b could both disrupt the integrity of MRSA membrane and form 4b-DNA supramolecular complex by intercalating into DNA. Moreover, tetrazolyl aloe-emodin 4b could bind with MRSA DNA isomerase at multiple sites through hydrogen bonds in molecular simulation.