Luteolin: A novel approach to fight bacterial infection

Diseases caused by bacteria significantly impact public health, causing both acute and chronic issues, sequelae, and death. The problems get even more significant, considering the antimicrobial resistance. Bacterial resistance occurs when antibacterial drugs fail to kill the microbes, leading to the persistence of infection and pathogen spread in the host. Thus, the search for new molecules with antibacterial activity dramatically impacts human health. Natural products have proven to be a prosperous source of these agents. Among them, the flavonoids deserve to be highlighted. They are secondary metabolites, primarily involved in plant signaling and protection. Thus, they play an essential role in plant adaptation to the environment. Herein, we will focus on luteolin because it is commonly found in edible plants and has diverse pharmacological properties such as anti-inflammatory, anticancer, antioxidant, and antimicrobial. We will further explore the luteolin antibacterial activity, mechanisms of action, structure-activity relationship, and toxicity of luteolin. Thus, we have included reports of luteolin with antibacterial activity recently published, as well as focused on nanotechnology as a pivotal and helpful approach for the clinical use of luteolin. This review aims to foster future research on luteolin as a therapeutic agent for treating bacterial infection.

Amino acid- and peptide-conjugated heterocyclic compounds: A comprehensive review of Synthesis Strategies and biological activities

Amino acids and peptides have long been recognized as promising candidates for therapeutic development due to their unique structural properties and high specificity. However, their clinical application is often limited by rapid enzymatic degradation, poor bioavailability, and suboptimal pharmacokinetics. Conjugating these biomolecules with heterocyclic compounds has emerged as a transformative strategy to enhance their stability, bioavailability, and overall therapeutic efficacy. This review highlights significant advancements since 2000 in the synthesis and biological applications of amino acid- and peptide-conjugated heterocyclic compounds These conjugates are categorized based on their nitrogen-, sulfur-, and oxygen-containing heterocyclic cores. Key synthetic methodologies, including amide bond formation, carbon-heteroatom coupling, and carbon-carbon bond formation, are discussed in detail. These conjugates exhibit enhanced pharmacological properties, with notable applications in antimicrobial, anticancer, and anti-inflammatory treatments. Despite these advancements, challenges such as synthetic complexity and potential toxicity remain. Future research should prioritize refining synthetic methodologies and leveraging underexplored heterocycles to unlock broader therapeutic applications. Peptide-heterocycle conjugates represent a promising approach to overcoming persistent challenges in modern drug development.

Thiazole - A promising scaffold for antituberculosis agents and structure-activity relationships studies

Research on thiazole derivatives has been a popular topic in medicine and one of the most active fields in heterocyclic chemistry. Pharmacological and industrial researchers have been studying thiazole-containing derivatives in great detail because they have a lot of biological uses. These compounds are one of the best examples of a five-membered heterocyclic compound that has a lot of potential and has had a lot of success in recent decades. Investigating viable hybrid designs utilizing thiazole is critical for the development of new anti-tuberculosis medications. This article offers a thorough overview of the latest advancements in thiazole-containing hybrids, offering potential therapeutic applications as anti-TB drugs. We also discussed the structure-activity correlations (SAR) of the powerful thiazole moiety and its several functional groups, along with a few potential molecular targets.

Antibacterial Potential of Ethyl 3,5-Dibromoorsellinate, a Derivative of Diphenyl Ethers from Graphis handelii, against Methicillin-Resistant Staphylococcus aureus

Staphylococcus aureus is a human pathogen responsible for a variety of diseases, from skin, soft tissue, and lung infections to severe cases such as meningitis, infective endocarditis, and bacteremia. The high level of antibiotic resistance in these pathogens, exemplified by methicillin-resistant Staphylococcus aureus (MRSA), necessitates the development of effective antibiotics. Thus, this work introduced the chemical synthesis of ethyl 3,5-dibromoorsellinate, a derivative of ethyl orsellinate from the lichen mycobiont of Graphis handelii, and its effectiveness against MRSA was assessed. Results showed that ethyl 3,5-dibromoorsellinate efficiently inhibited MRSA with a minimum inhibitory concentration (MIC) of 4 μg/mL, and the time-kill analysis showed the bactericidal effect of ethyl 3,5-dibromoorsellinate on MRSA at 8× MIC after 24 h. The compound also exhibited selective activity against MRSA compared with the human cell line, with a selectivity index of 12.5-fold. While ethyl 3,5-dibromoorsellinate exhibited an indifferent effect with ampicillin, this compound demonstrated antagonistic effects with kanamycin in the synergistic assessment. Additionally, ethyl 3,5-dibromoorsellinate demonstrated antibiofilm activity against MRSA starting from 0.25× MIC. The molecular docking investigation illustrated that ethyl 3,5-dibromoorsellinate binds with the penicillin-binding protein 2A of MRSA with a free energy of -42.5 to -45.7 kcal/mol. Given its promising antibacterial activities, ethyl 3,5-dibromoorsellinate warrants further investigation as a potential antibiotic option against MRSA.

Application of Drug Delivery System Based on Nanozyme Cascade Technology in Chronic Wound

Chronic wounds are characterized by long-term inflammation, including diabetic ulcers, traumatic ulcers, etc., which provide an optimal environment for bacterial proliferation. At present, antibiotics are the main clinical treatment method for chronic wound infections. However, the overuse of antibiotics may accelerate the emergence of drug-resistant bacteria, which poses a significant threat to human health. Therefore, there is an urgent need to develop new therapeutic strategies for bacterial infections. Nanozyme-based antimicrobial therapy (NABT) is an emerging antimicrobial strategy with broad-spectrum activity and low drug resistance compared to traditional antibiotics. NABT has shown great potential as an emerging antimicrobial strategy by catalyzing the generation of reactive oxygen species (ROS) with its enzyme-like catalytic properties, producing a powerful bactericidal effect without developing drug resistance. Nanozyme-based cascade antimicrobial technology offers a new approach to infection control, effectively improving antimicrobial efficacy by activating cascades against bacterial cell membranes and intracellular DNA while minimizing potential side effects. However, it is worth noting that this technology is still in the early stages of research. This article comprehensively reviews wound classification, current methods for the treatment of wound infection, different types of nanozymes, the application of nanozyme cascade reaction technology in antimicrobial therapy, and future challenges and prospects.

Fluoroquinolones tackling antimicrobial resistance: Rational design, mechanistic insights and comparative analysis of norfloxacin vs ciprofloxacin derivatives

Antimicrobial resistance poses a global health concern and develops a need to discover novel antimicrobial agents or targets to tackle this problem. Fluoroquinolone (FN), a DNA gyrase and topoisomerase IV inhibitor, has helped to conquer antimicrobial resistance as it provides flexibility to researchers to rationally modify its structure to increase potency and efficacy. This review provides insights into the rational modification of FNs, the causes of resistance to FNs, and the mechanism of action of FNs. Herein, we have explored the latest advancements in antimicrobial activities of FN analogues and the effect of various substitutions with a focus on utilizing the FN nucleus to search for novel potential antimicrobial candidates. Moreover, this review also provides a comparative analysis of two widely prescribed FNs that are ciprofloxacin and norfloxacin, explaining their rationale for their design, structure-activity relationships (SAR), causes of resistance, and mechanistic studies. These insights will prove advantageous for new researchers by aiding them in designing novel and effective FN-based compounds to combat antimicrobial resistance.

Bioflavonoid Baicalein Modulates Tetracycline Resistance by Inhibiting Efflux Pump in Staphylococcus aureus

The rise in antibiotic resistance among bacterial pathogens, particularly Staphylococcus aureus, has become a critical global health issue, necessitating the search for novel antimicrobial agents. S. aureus uses various mechanisms to resist antibiotics, including the activation of efflux pumps, biofilm formation, and enzymatic modification of drugs. This study explores the potential of baicalein, a bioflavonoid from Scutellaria baicalensis, in modulating tetracycline resistance in S. aureus by inhibiting efflux pumps. The synergistic action of baicalein and tetracycline was evaluated through various assays. The minimum inhibitory concentration (MIC) of baicalein and tetracycline against S. aureus was 256 and 1.0 μg/mL, respectively. Baicalein at 64 μg/mL reduced the MIC of tetracycline by eightfold, indicating a synergistic effect (fractional inhibitory concentration index: 0.375). Time-kill kinetics demonstrated a 1.0 log CFU/mL reduction in bacterial count after 24 hours with the combination treatment. The ethidium bromide accumulation assay showed that baicalein mediated significant inhibition of efflux pumps, with a dose-dependent increase in fluorescence. In addition, baicalein inhibited DNA synthesis by 73% alone and 92% in combination with tetracycline. It also markedly reduced biofilm formation and the invasiveness of S. aureus into HeLa cells by 52% at 64 μg/mL. These findings suggest that baicalein enhances tetracycline efficacy and could be a promising adjunct therapy to combat multidrug-resistant S. aureus infections.

Development of novel indole-quinoline hybrid molecules targeting bacterial proton motive force

AIMS

This study aimed to develop an editable structural scaffold for improving drug development, including pharmacokinetics and pharmacodynamics of antibiotics by using synthetic compounds derived from a (hetero)aryl-quinoline hybrid scaffold.

METHODS AND RESULTS

In this study, 18 CF3-substituted (hetero)aryl-quinoline hybrid molecules were examined for their potential antibacterial activity against Staphylococcus aureus by determining minimal inhibitory concentrations. These 18 synthetic compounds represent modifications to key regions of the quinoline N-oxide scaffold, enabling us to conduct a structure-activity relationship analysis for antibacterial potency. Among the compounds, 3 m exhibited potency against with both methicillin resistant S. aureus strains, as well as other Gram-positive bacteria, including Enterococcus faecalis and Bacillus subtilis. We demonstrated that 3 m disrupted the bacterial proton motive force (PMF) through monitoring the PMF and conducting the molecular dynamics simulations. Furthermore, we show that this mechanism of action, disrupting PMF, is challenging for S. aureus to overcome. We also validated this PMF inhibition mechanism of 3 m in an Acinetobacter baumannii strain with weaken lipopolysaccharides. Additionally, in Gram-negative bacteria, we demonstrated that 3 m exhibited a synergistic effect with colistin that disrupts the outer membrane of Gram-negative bacteria.

CONCLUSIONS

Our approach to developing editable synthetic novel antibacterials underscores the utility of CF3-substituted (hetero)aryl-quinoline scaffold for designing compounds targeting the bacterial proton motive force, and for further drug development, including pharmacokinetics and pharmacodynamics.

Antimicrobial peptides: An alternative to traditional antibiotics

As antibiotic-resistant bacteria and genes continue to emerge, the identification of effective alternatives to traditional antibiotics has become a pressing issue. Antimicrobial peptides are favored for their safety, low residue, and low resistance properties, and their unique antimicrobial mechanisms show significant potential in combating antibiotic resistance. However, the high production cost and weak activity of antimicrobial peptides limit their application. Moreover, traditional laboratory methods for identifying and designing new antimicrobial peptides are time-consuming and labor-intensive, hindering their development. Currently, novel technologies, such as artificial intelligence (AI) are being employed to develop and design new antimicrobial peptide resources, offering new opportunities for the advancement of antimicrobial peptides. This article summarizes the basic characteristics and antimicrobial mechanisms of antimicrobial peptides, as well as their advantages and limitations, and explores the application of AI in antimicrobial peptides prediction amd design. This highlights the crucial role of AI in enhancing the efficiency of antimicrobial peptide research and provides a reference for antimicrobial drug development.

Design, Synthesis and Evaluation of Antifungal Activity of Pyrazoleacetamide Derivatives

BACKGROUND

Fungal infections have posed a big challenge in the management of their treatment. Due to the resistance and toxicity of existing drug molecules in the light of pandemic infections, like COVID-19, there is an urgent need to find newer derivatives of active molecules, which can be effective in fungal infections.

OBJECTIVE

In the present study, we aimed to design pyrazole derivatives using molecular modeling studies against target 1EA1 and synthesize 10 molecules of pyrazole derivatives using a multi-step synthesis approach.

METHODS

Designed pyrazole derivatives were synthesized by conventional organic methods. The newly synthesized pyrazole molecules were characterized by using FT-IR, 1HNMR, 13CNMR, and LC-MS techniques. Molecular docking studies were also performed. The antifungal activity of newly synthesized compounds was assessed in vitro against Candida albicans and Aspergillus niger using the well plate method.

RESULTS

Two of the compounds, OK-7 and OK-8, have been found to show significant docking interaction with target protein 1EA1. These two compounds have also been found to show significant anti-fungal activity against Candida albicans and Aspergillus nigra when compared to the standard fluconazole. The Minimum Inhibitory Concentration (MIC) value of these two compounds has been found to be 50 μg/ml.

CONCLUSION

Pyrazole derivatives with -CH3, CH3O-, and -CN groups have been found to be active against tested fungi and can be further explored for their potential as promising anti-fungal agents for applications in the field of medicinal chemistry.

A new antimicrobial PVC-based polymeric material incorporating bisacylthiourea complexes

A new antimicrobial material incorporating Cu(I) and Cd(II) complexes of bisacylthiourea derivatives in a PVC film was successfully synthesized and characterized by IR, UV, NMR, SEM, and thermal analyses. The results revealed that on coordination, the electronic structure change of the ligand affects practically all their spectral vibrational pattern; however, within the complex pattern, some vibrations indicated that the thiourea derivative behaves as a neutral ligand, which coordinates the metal ion through the sulfur atom of the thiocarbonyl group. The greater affinity of the S atom for Cu^+ 1 played a role in Cu(II)→Cu(I) reduction, and the intramolecular hydrogen bonds of the type of (NH···Cl) further stabilized the obtained Cu(I) complex in dioxane. The antimicrobial activity shows that all investigated compounds exhibit excellent activity compared to standard antibiotics. The antibacterial power of the PVC/Cd composite is significantly superior against the most resistant species to both disinfectants and antibiotics compared to its PVC/Cu analogue; nevertheless, the latter exhibited activity equal to an average halo diameter of 29 ± 0.33 mm against pathogenic E. coli ATCC 25,922, indicating excellent G (-) activity. Interestingly, the PVC/Cd composite exhibited excellent activity against pathogenic C. albicans RCMB 005003 (1) ATCC 10,231, while its PVC/Cu analogue was inactive. These materials may be used to reduce infection in wounds either as a composite film or coated barrier dressings, and in addition, the results should open a new direction in antimicrobial surface engineering within the biomedical field. Further challenges are the development of reusable and broad-range antimicrobial polymers..

Structure based design and synthesis of 3-(7-nitro-3-oxo-3,4-dihydroquinoxalin-2-yl)propanehydrazide derivatives as novel bacterial DNA-gyrase inhibitors: In-vitro, In-vivo, In-silico and SAR studies

Antimicrobial resistance (AMR) is one of the critical challenges that have been encountered over the past years. On the other hand, bacterial DNA gyrase is regarded as one of the most outstanding biological targets that quinolones can extensively inhibit, improving AMR. Hence, a novel series of 3-(7-nitro-3-oxo-3,4-dihydroquinoxalin-2-yl)propanehydrazide derivatives (3-6j) were designed and synthesized employing the quinoxaline-2-one scaffold and relying on the pharmacophoric features experienced by the quinolone antibiotic; ciprofloxacin. The antibacterial activity of the synthesized compounds was assessed via in-vitro approaches using eight different Gram-positive and Gram-negative bacterial species. Most of the synthesized compounds revealed eligible antibacterial activities. In particular, compounds 6d and 6e displayed promising antibacterial activity among the investigated compounds. For example, compounds 6d and 6e displayed MIC values of 9.40 and 9.00 µM, respectively, regarding S. aureus, and 4.70 and 4.50 µM, respectively, regarding S. pneumonia in comparison to ciprofloxacin (12.07 µM). The cytotoxicity of compounds 6d and 6e were performed on normal human WI-38 cell lines with IC50 values of 288.69 and 227.64 μM, respectively assuring their safety and selectivity. Besides, DNA gyrase inhibition assay of compounds 6d and 6e was carried out in comparison to ciprofloxacin, and interestingly, compounds 6d and 6e disclosed promising IC50 values of 0.242 and 0.177 μM, respectively, whereas ciprofloxacin displayed an IC50 value of 0.768 μM, assuring the proposed mechanism of action for the afforded compounds. Consequently, compounds 6d and 6e were further assessed via in-vivo approaches by evaluating blood counts, liver and kidney functions, and histopathological examination. Both compounds were found to be safer on the liver and kidney than the reference ciprofloxacin. Moreover, in-silico molecular docking studies were established and revealed reasonable binding affinities for all afforded compounds, particularly compound 6d which exhibited a binding score of -7.51 kcal/mol, surpassing the reference ciprofloxacin (-7.29 kcal/mol) with better anticipated stability at the DNA gyrase binding pocket. Moreover, ADME studies were conducted, disclosing an eligible bioavailability score of >0.55 for all afforded compounds, and reasonable GIT absorption without passing the blood brain barrier was attained for most investigated compounds, ensuring their efficacy and safety. Lastly, a structure activity relationship study for the synthesized compounds was established and unveiled that not only the main pharmacophores required for DNA gyrase inhibition are enough for exerting promising antimicrobial activities, but also derivatization with diverse aryl/hetero aryl aldehydes is essential for their enhanced antimicrobial potential.

Comparison of Molecular Characteristics Between Methicillin-Resistant and -Susceptible Staphylococcus aureus Clinical Isolates by Whole-Genome Sequencing

Introduction

The transmission of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible Staphylococcus aureus (MSSA) are great public health concern worldwide. To better understand S. aureus evolution and dissemination, we compared the molecular features of MSSA and MRSA isolates.

Methods

In this study, 74 MSSA and 102 MRSA non-duplicate isolates were recovered from clinical samples between 2016 and 2020. Molecular epidemiology, antimicrobial resistance determinants, and virulence gene profiles were carried out by whole-genome sequencing (WGS).

Results

Twenty distinct sequence types were identified in MRSA isolates, with the most common being ST59, ST630, and ST338. The major genotypes of MSSA were ST188 and ST7. The toxin genes clfA, sek, and seq were significantly associated with MRSA, while splA/B, clfB, map, sdrC/D, and sem-sen-seo-seu were detected more frequently in MSSA isolates than MRSA (P < 0.05). The tst positive isolates were more commonly identified in CC1 and CC72, whereas lukE/D was mainly found in the CC7, CC15, CC88, and completely absent in CC59 clones.

Conclusion

Our results compared the genetic diversity between MRSA and MSSA strains, suggesting efforts to fight infections caused by MSSA need to be intensified due to MSSA isolates carrying wide range of virulence factors. Comparative epidemiological studies of large populations of MSSA and MRSA will be necessary in the future to understand how MSSA and MRSA populations may co-evolve and interact in the future.

Alternative approaches utilizing click chemistry to develop next-generation analogs of solithromycin

The marked rise in bacterial drug resistance has created an urgent need for novel antibacterials belonging to new drug classes and ideally possessing new mechanisms of action. The superior biological activity of solithromycin against streptococci and other bacteria causative of community-acquired pneumonia pathogens, compared to telithromycin and other macrolides encouraged us to extensively explore this class of antibiotics. We, thus, present the design and synthesis of a novel series of solithromycin analogs. Three main strategies were pursued in structure-activity relationship studies covering the N-11 side chain and the desosamine motif, which are both chief elements for establishing strong interactions with the bacterial ribosome as the molecular target. Minimal inhibitory concentration assays were determined to assess the in vitro potency of the various analogs in relation to solithromycin. Two analogs exhibited improved activity compared to solithromycin against resistant strains, which can be assessed in further pre-clinical studies.

Design, synthesis, biological screening and molecular docking studies of novel multifunctional 1,4-di (aryl/heteroaryl) substituted piperazine derivatives as potential antitubercular and antimicrobial agents

In this paper, two series of novel multifunctional 1, 4-di (aryl/heteroaryl) substituted piperazine derivatives (6a-d & 7a-d) were synthesized, characterized, and evaluated for their antitubercular, antibacterial, and antifungal activities. A step-wise reduction, bromination and substitution reactions on various aldehydes resulted in alcohols (2a-d), bromides (3a-d), and titled novel compounds (6a-d & 7a-d) in moderate to good yields (48-85%). The novel compounds were evaluated for their antitubercular and antimicrobial activities. Compound 7a exhibited promising antitubercular activity (MIC: 0.65 µg/mL) almost equal to the Rifampicin, while the rest of the compounds were moderately active against MTB H37Rv except 6b. Compounds 7a and 6b showed good activity against tested fungal pathogens. Compounds 7a and 7b were proven as the best bacterial agents. Molecular docking studies were in agreement with the in-vitro results. Docking analyses show that all the synthesized molecules bind to the target protein Mtb RNAP (PDB ID: 5UHC) fairly strongly. All the compounds were evaluated for their in vitro cytotoxicity effect using the MTT assay method against human cancer cell line MCF-7. The compounds demonstrated growth inhibitory effect on the cell line with significant IC₅₀ values ranging between 8.20 and 34.45 µM. Most importantly, compound 7a displayed good binding affinity towards the tested protein with binding energy -7.30 kcal/mol and a stronger hydrogen bond distance of 2.2 Å with ASN-493 residue. Thus, the present research highlighted the potential role of novel piperazine derivatives as potential antitubercular, and antimicrobial candidates and further good research into optimization might result in the development of new antitubercular drug candidates.

Generation of truncated derivatives through in silico enzymatic digest of peptide GV30 target MRSA both in vitro and in vivo

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A novel host-defence peptide GV30 was identified from the frog skin secretion of Hylarana guentheri.

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Seven short AMPs were generated by in silico enzymatic digest of GV30 using an online proteomic bioinformatic tool PeptideCutter in ExPASy server.

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Two truncated products, GV23 and GV21, exhibited an improved antibacterial effect against MRSA in vitro and demonstrated a faster bactericidal effect than the parent peptide.

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GV 21 was found to have a better in vivo anti-MRSA activity and retain the good antibacterial activity under salt and serum conditions, along with lower toxicity.

Methicillin-resistant Staphylococcus aureus (MRSA) causing serious hospital-acquired infections and skin infections has become a “superbug” in clinical treatment. Although the clinical treatment of MRSA is continuously improving, due to its unceasing global spread, MRSA has produced much heated discussion and focused study, therefore suggesting an urgent task to find new antibacterial drugs to combat this issue. Antimicrobial peptides (AMPs) are used as the last-resort drugs for treating multidrug-resistant bacterial infections, but their utilisation is still limited due to their low stability and often strong toxicity.

Here, we evaluated the structure and the bioactivity of an AMP, GV30, derived from the frog skin secretions of Hylarana guentheri, and designed seven truncated derivatives based on the presence of cleavage sites for trypsin using an online proteomic bioinformatic resource PeptideCutter tool. We investigated the anti-MRSA effect, toxicity and salt- and serum-resistance of these peptides. Interestingly, the structure–activity relationship revealed that removing “Rana box” loop could significantly improve the bactericidal speed on MRSA. Among these derivatives, GV21 (GVIFNALKGVAKTVAAQLLKK-NH₂), because of its faster antibacterial effect, lower toxicity, and retains the good antibacterial activity and stability of the parent peptide, is considered to become a new potential antibacterial candidate against MRSA.

Synergistic effect of curcumin-Cu and curcumin-Ag nanoparticle loaded niosome: Enhanced antibacterial and anti-biofilm activities

In the current study, for the first time, the synergistic activity of curcumin and silver/copper nanoparticles (NPs) was studied against Staphylococcus aureus and Pseudomonas aeruginosa. Moreover, a unique combination of curcumin and silver/copper NPs in free and encapsulated forms was prepared and delivered through a niosomal system. For this purpose, different niosomal formulations of curcumin and metal NPs were prepared by thin film hydration method. Then, the dual drug-loaded niosomes were dispersed in chitosan hydrogel in order to widen its applications. The effect of the molar ratios of lipid to drug and surfactant to cholesterol was investigated to find the optimized noisomal nanoparticles in terms of size, polydispersity index (PDI), and entrapment efficiency (EE). The size and PDI values were measured by dynamic light scattering (DLS). Morphology and in vitro drug release kinetics of niosomes were examined by scanning and transmission electron microscopy (SEM, TEM) and dialysis method, respectively. The drug-loaded niosomes and their hydrogel counterpart were screened for investigating their antibacterial activity against S. aureus and P. aeruginosa by disk diffusion, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) assays. Furthermore, anti-biofilm assay and expression of biofilm-associated genes by Real-time PCR were performed to evaluate the anti-biofilm effect of NPs. In this study, the drug-loaded niosomal formulations showed good entrapment efficiencies (EE) with a sustained release profile over 72 h. Moreover, compared to free drugs, the optimized niosomal formulations increased antibacterial activity against the bacteria via promotion in the inhibition zone and reduction in MIC and MBC values. Interestingly, gel-based niosomal formulations increased the inhibition zone by about 6 mm and significantly decreased MIC and MBC values compared to niosomal formulations. Also, biofilm eradication of curcumin-metal NPs encapsulated into niosomal hydrogel was highest compared to free and niosomal drugs. Overall, curcumin-Cu or curcumin-Ag nanoparticle loaded niosomes incorporated in hydrogel hold great promise for biomedical applications.

Pectin modified with phenolic acids: Evaluation of their emulsification properties, antioxidation activities, and antibacterial activities

Three phenolic acids including p-hydroxybenzoic acid (PHBA), 3,4-dihydroxybenzoic acid, (DHBA), and gallic acid (GA) were grafted onto native pectin (Na-Pe) through enzymatic method. Ultraviolet-visible spectrometry, Fourier transform infrared spectroscopy, and ¹H NMR analyses were used to explore the reaction mechanism. Results indicated that the p-hydroxyl of the phenolic acids reacted with the methoxycarbonyl of pectin through transesterification, and a covalent connection was formed. The phenolic acid contents of PHBA modified pectin (Ph-Pe), DHBA modified pectin (Dh-Pe), and GA modified pectin (Ga-Pe) were 20.18%, 18.87%, and 20.32%, respectively. After acylation with phenolic acids, the 1,1-diphenyl-2-picryl hydrazine clearance of pectin changed from 7.68% (Na-Pe) to 6.88% (Ph-Pe), 40.80% (Dh-Pe), and 90.30% (Ga-Pe), whereas its inhibition ratio of pectin increased from 3.11% (Na-Pe) to 35.02% (Ph-Pe), 66.36% (Dh-Pe), and 77.89% (Ga-Pe). Moreover, compared with Na-Pe, modified pectins exhibited better emulsification properties and stronger antibacterial activities against both Escherichia coli and Staphylococcus aureus.

ConjuPepDB: a database of peptide-drug conjugates

Peptide–drug conjugates are organic molecules composed of (i) a small drug molecule, (ii) a peptide and (iii) a linker. The drug molecule is mandatory for the biological action, however, its efficacy can be enhanced by targeted delivery, which often also reduces unwanted side effects. For site-specificity the peptide part is mainly responsible. The linker attaches chemically the drug to the peptide, but it could also be biodegradable which ensures controlled liberation of the small drug. Despite the importance of the field, there is no public comprehensive database on these species. Herein we describe ConjuPepBD, a freely available, fully annotated and manually curated database of peptide drug conjugates. ConjuPepDB contains basic information about the entries, e.g. CAS number. Furthermore, it also implies their biomedical application and the type of chemical conjugation employed. It covers more than 1600 conjugates from ∼230 publications. The web-interface is user-friendly, intuitive, and useable on several devices, e.g. phones, tablets, PCs. The webpage allows the user to search for content using numerous criteria, chemical structure and a help page is also provided. Besides giving quick insight for newcomers, ConjuPepDB is hoped to be also helpful for researchers from various related fields. The database is accessible at: https://conjupepdb.ttk.hu/.

Exploring the properties and potential biomedical applications of NSAID-capped peptide hydrogels

The development of strategies to minimise the adverse side-effects of non-steroidal anti-inflammatory drugs (NSAIDs) remains a challenge for medicinal chemists. One such strategy is the development of NSAID-peptide prodrug conjugates and this conjugation to a peptide often confers the additional property of hydrogelation. This review summarises the work published by our research group, alongside other research groups, on supramolecular hydrogels consisting of short peptides conjugated to NSAIDs. Generally, supramolecular low molecular weight hydrogels (LMWHs) are composed of amphiteric molecules, usually consisting of short peptides attached to an aromatic capping group. When the aromatic capping group is switched for an NSAID to afford hybrid gelators, some conjugates exhibit retained or improved anti-inflammatory properties of the parent drug, and sometimes new and unexpected biological activities are observed. Conjugation to peptides often provides selective COX-2 inhibition over COX-1 inhibtion, which is key to retaining the anti-inflammatory benefits of NSAIDs whilst minimising gastric side-effects. Naproxen is the most commonly employed NSAID capping group, partly due to its similarity in structure to commonly employed naphthalene capping groups. Biomimetic approaches, where canonical amino acids are switched for non-natural amino acids such as d-amino acids or dehydroamino acids, are often employed, to tune the stability. The future direction for this area of research is discussed.

Pyridine- and Thiazole-Based Hydrazides with Promising Anti-inflammatory and Antimicrobial Activities along with Their In Silico Studies

A new class of compounds formed by the linkage of -C(O)-NH- with pyridine and thiazole moieties was designed, synthesized, and characterized by various spectral approaches. The newly characterized compounds were evaluated for their antimicrobial as well as anti-inflammatory properties. The in vitro anti-inflammatory activity of these compounds was evaluated by denaturation of the bovine serum albumin method and showed inhibition in the range of IC50 values-46.29-100.60 μg/mL. Among all the tested compounds, compound 5l has the highest IC50 value and compound 5g has the least IC50 value. On the other hand, antimicrobial results revealed that compound 5j showed the lowest MIC values and compound 5a has the highest MIC values. Furthermore, molecular docking of the active compounds demonstrated a better docking score and interacted well with the target protein. Physicochemical parameters of the titled compounds were found suitable in the reference range only. The in silico molecular docking study revealed their COX-inhibitory action. Compound 5j emerged as a significant bioactive molecule among the synthesized analogues.

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.

Anticancer and DNA binding studies of potential amino acids based quinazolinone analogs: Synthesis, SAR and molecular docking

A novel series of amino acids conjugated quinazolinone-Schiff's bases were synthesized and screened for their in vitro anticancer activity and validated by molecular docking and DNA binding studies. In the present investigations, compounds 32, 33, 34, 41, 42 and 43 showed most potent anticancer activity against tested cancer cell lines and DNA binding study using methyl green comparing to doxorubicin and ethidium bromide as a positive control respectively. The structure-activity relationship (SAR) revealed that the tryptophan and phenylalanine derived electron donating groups (OH and OCH₃) favored DNA binding studies and anticancer activity whereas; electron withdrawing groups (Cl, NO₂, and F) showed least anticancer activity. The molecular docking study, binding interactions of the most active compounds 33, 34, 42 and 43 stacked with A-T rich regions of the DNA minor groove by surface binding interactions were confirmed.