Effective Antibacterial Agent Research Articles

Amine-substituted heterocyclic thioamide Cu(I) and Ag(I) complexes as effective anticancer and antibacterial agents targeting the periplasm of E. coli bacteria

Metal complexes showing dual activity against cancer and bacterial infections are currently the focus of significant interest for their potential in treating life-threatening diseases. Aiming to investigate the impact of ligand substituents on these bioactivity properties of Group 11 d10 metal complexes, we herein present a series of mononuclear Cu(I) and Ag(I) complexes featuring the bis–NH2–substituted heterocyclic thioamide dap2SH (=4,6-diaminopyrimidine-2-thione), namely [AgCl(dap2SH)(PPh3)2] (1), [CuBr(dap2SH)(PPh3)2] (2), [CuBr(dap2SH)(xantphos)] (3), [Ag(dap2S)(xantphos)] (4), and [Cu(dap2S)(xantphos)] (5) (xantphos = 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene). Complexes were characterized by means of different physicochemical methods (i.e., single crystal X-ray diffraction as well as FTIR, NMR, UV–Vis and fluorescence spectroscopy), and studied in-vitro for their antibacterial and anticancer activity against a variety of bacterial strains and cancer cell lines. Complexes 1–3 effectively inhibited both Gram (+) and Gram (−) bacterial growth, while cellular uptake studies for the most potent complex 1 against E. coli bacteria revealed the accumulation of Ag(I) ions in the periplasm of the bacteria. A high anti-proliferative effect was observed for 1 and 5 against A549, MCF7 and PC3 cancer cell lines, with 1 being capable of inducing apoptosis in A549 cells, as suggested by flow cytometry analysis. DNA interaction studies revealed the capacity of 1 to intercalate between base-pairs of CT DNA. All complexes had a moderate-to-high capacity to scavenge free radicals preventing oxidative stress. Molecular docking calculations, in combination with the experimentally obtained data, provided insights for potential mechanisms of the bioactivity of the complexes.

Discovery of quaternized pyridine-thiazole-ruthenium complexes as potent anti-Staphylococcus aureus agents

Quaternization of ruthenium complexes may be a promising strategy for the development of new antibiotics. In response to the increasing bacterial resistance, we integrated the quaternary amine structure into the design of ruthenium complexes and evaluated their antibacterial activity. All the ruthenium complexes showed good antibacterial activity against the tested Staphylococcus aureus (S. aureus). Ru-8 was the most effective antibacterial agent that displayed excellent antibacterial activity against S. aureus (MIC = 0.78–1.56 μg/mL). In vitro experiments showed that all nine ruthenium complexes had low hemolytic toxicity to rabbit erythrocytes. Notably, Ru-8 was found to disrupt bacterial cell membranes, alter their permeability, and induce ROS production in bacteria, all the above leading to the death of bacteria without inducing drug resistance. To further explore the antibacterial activity of Ru-8in vivo, we established a mouse skin wound infection model and a G. mellonella larvae infection model. Ru-8 exhibited significant antibacterial efficacy against S. aureus in vivo and low toxicity to mouse tissues. The Ru-8 showed low toxicity to Raw264.7 cells (mouse monocyte macrophage leukemia cells). This study indicates that the ruthenium complex ruthenium quaternary was a promising strategy for the development of new antibacterial agents.

Growth inhibition of P. aeruginosa by methanol extract of Bridelia stipularis and identification of active components using in silico studies

BackgroundAntimicrobial resistance among pathogens is an emerging problem, gaining significant importance recently. Pharmaceutical scientists are constantly exploring innovative and effective antibacterial agents. Pseudomonas aeruginosa (P. aeruginosa) is a bacterium primarily responsible for pneumonia and infections in the liver, kidneys, and other body parts. It is a Gram-negative bacterium that can be controlled by antibiotics such as ciprofloxacin and levofloxacin. However, this pathogen sometimes exhibits resistance to these antibacterial agents.MethodsRecognizing the well-known potential of plants as sources of medicinal compounds, our study focused on the ethyl acetate, acetone and methanol extract of the leaves of Bridelia stipularis and its impact on the growth of P. aeruginosa using well diffusion method. To gain insight into the composition of the extract, we conducted GC–MS analysis. After identifying the components present in the extract, we assessed the drug-likeness, absorption, distribution, metabolism, and excretion (ADME) and conducted docking studies of the molecules with the selected structural receptors of P. aeruginosa to find out the active component present in the extract.ResultsRemarkably, only methanol extract of Bridelia stipularis demonstrated significant antibacterial activity against this pathogen. In silico investigations revealed that two compounds, namely ethyl iso-allocholate and toluene sulfonylhydrazone derivative, exhibited high inhibition potencies. All structural receptors of the pathogen taken for this study were well inhibited by ethyl iso-allocholate while the receptors such as laconizing lipase and penicillin-binding protein of the bacterium were bound well with the 4-phenyl-3-penten-2-one p-toluene sulfonylhydrazone.ConclusionsObservations of this study clearly establish that the two phytochemicals present in the methanolic extract, i.e., ethyl iso-allocholate and toluene sulfonylhydrazone derivative of Bridelia stipularis leaves are highly active against the growth of the opportunistic pathogen P. aeruginosa.Graphical abstract

Synthesis and evaluation of di-heterocyclic benzazole compounds as potential antibacterial and anti-biofilm agents against Staphylococcus aureus.

Cumulative escalation in antibiotic-resistant pathogens necessitates the quest for novel antimicrobial agents, as current options continue to diminish bacterial resistance. Herein, we report the synthesis of di-heterocyclic benzazole structures (12-19) and their invitro evaluation for some biological activities. Compounds 16 and 17 demonstrated potent antibacterial activity (MIC = 7.81 μg/mL) against Staphylococcus aureus, along with significant anti-biofilm activity. Noteworthy is the capability of Compound 17 to inhibit biofilm formation by at least 50% at sub-MIC (3.90 μg/mL) concentration. Furthermore, both compounds exhibited the potential to inhibit preformed biofilm by at least 50% at the MIC concentration (7.81 μg/mL). Additionally, Compounds 16 and 17 were examined for cytotoxic effects in HFF-1 cells, using the MTT method, and screened for binding interactions within the active site of S. aureus DNA gyrase using in silico molecular docking technique, employing AutoDock 4.2.6 and Schrödinger Glidse programs. Overall, our findings highlight Compounds 16 and 17 as promising scaffolds warranting further optimization for the development of effective antibacterial and anti-biofilm agents.

Exploring the pharmacological potential of Lepionurus sylvestris blume: from folklore medicinal usage to modern drug development strategies using in vitro and in silico analyses

BackgroundLepionurus sylvestris Blume has a long history of folklore medicinal usage against various ailments. However, studies on these plants were neglected particularly their pharmacological potential.MethodsThe crude extract was identified using LC-MS analysis. In vitro assays were carried out to determine the properties of antioxidant, anti-microbial, and anti-cancer. Further, network pharmacology was proposed to evaluate the potential targets of the compounds against breast cancer and type II diabetes. Molecular docking and molecular dynamic simulation were used to determine the potential compounds for the drug formulation of diabetes.ResultsVarious bioactive compounds were identfied using LC-MS and Galiposin, Fujikinetin, Boeravinone B, 4-Deoxybryaquinone, and Norbaeocystin were described for the first time from the plant. Determination of antioxidant potential showed that the IC50 value of ABTS, DPPH, and phosphomolybdate was 24.33 µg/ml, 37.81 µg/ml, 60.35 µg/ml, and reducing power assays 1.185. The antibacterial activity against Streptococcus pyogenes, Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli was determined, and the minimum inhibition concentration (MIC) was found to be 5.3 mg/ml, 3.47 mg/ml, 3.33 mg/ml, and 2.7 mg/ml respectively, revealing the extracts as effective antibacterial agents. The IC50 values for the plant extract were determined to be 26 µg/ml, 30.52 µg/ml, and 24.39 µg/ml for HeLa, MCF-7, and K-562 cells, respectively, and the increasing concentration of the plant extract increased LDH release. Furthermore, the in silico network pharmacology, molecular docking which had the highest docking score for GAPDH and HIF-1 target proteins of -9.3 kcal/mol, and − 11.3 kcal/mol binding affinities, and molecular dynamic simulation analysis revealed the bioactive compound Boeravinone B present in the plant was significant for the treatment of various ailments.ConclusionBased on our findings, plant extracts could be a promising option for developing new drug formulations.

Sono-synthesis and characterization of next-generation antimicrobial ZnO/TiO2 and Fe3O4/TiO2 bi-nanocomposites, for antibacterial and antifungal applications

Ultrasonic-assisted synthesis of ZnO/TiO₂ and Fe₃O₄/TiO₂ bi-oxide nanocomposites at low frequencies (60 kHz) with their characterizations and antibacterial/antifungal applications are investigated in this study. Using nanotechnology as the next-generation solution, this research explored the potential of metal oxide nanoparticles as effective antibacterial agents. Nanomaterials were synthesized via a novel and facile method (sono-synthesis) and characterized using various techniques (XRD, SEM, FTIR, zeta potential analysis, Raman spectroscopy, and XPS), revealing nanoscale sizes of 25 nm for ZnO/TiO₂ and 31 nm for Fe₃O₄/TiO₂. Structural analysis demonstrated the distinct crystalline phases of the synthesized nanomaterials: TiO₂ with anatase structure (25 %), hexagonal wurtzite structure for ZnO, and Fe₃O₄ with inverse spinel structure, formed in nano-dimensions (19–31 nm) with a near-spherical shape. Antibacterial and antifungal assays highlighted the efficacy of both bi-nanocomposites against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria, along with their potent activity against Candida albicans and non-albicans Candida. Moreover, principal component analysis (PCA) was used to identify potential relationships between the physicochemical properties (zeta potential, size, conductivity, and concentration) of all nanomaterials tested and their zone of inhibition (ZOI) against all bacterial species tested. Overall, this study emphasizes the novelty of employing a simple and efficient sono-synthetic route to synthesize ZnO/TiO₂ and Fe₃O₄/TiO₂ bi-nanocomposites and investigate their significant antibacterial and antifungal activities. Additionally, it identifies the potential relationships between the physicochemical properties of the nanomaterials tested and their antimicrobial activity. This approach provides a robust framework for future applications of bi-nanocomposites in combating microbial infections.

Antimicrobial, phytochemical, and antioxidant characterization of the leaf extracts of Clematis montana and Clematis grata

The worldwide emergence of multidrug-resistant bacterial infections among the population has impaired the existing effectiveness of antimicrobial treatments, necessitating the hunt for other alternatives. We aimed to find the antibacterial and antioxidant activities of Clematis montana and C. grata leaf extracts (both species have medicinal use among the local population). Extracts were assessed against four pathogenic bacterial strains (Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, and Staphylococcus aureus), through the agar well diffusion method. Total flavonoid content (TFC), total phenolic content (TPC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity were quantified. Results suggested that all plant extracts, particularly those extracted with methanol, were potentially active in suppressing pathogenic bacterial growth (particularly against P. aeruginosa and E. coli) although their efficiency varied when compared to vancomycin. However, the antibacterial activity of methanolic extracts from both species was not greatly influenced by the method of extraction (maceration/soxhlet apparatus). TFC was significantly higher in the methanolic extracts of both species in comparison to the n-hexane extracts, whereas TPC and DPPH scavenging activity were detected to be highest in the methanolic extract from the leaves of C. grata. Our results suggested that the leaf extracts from both Clematis species, particularly the methanolic-based extract of C. montana, might serve as a promising source of an effective antibacterial agent.

In silico exploration of 4(α-l-rhamnosyloxy)-benzyl isothiocyanate: A promising phytochemical-based drug discovery approach for combating multi-drug resistant Staphylococcus aureus

Multidrug-resistant (MDR) Staphylococcus aureus infections significantly threaten global health. With rising resistance to current antibiotics and limited solutions, the urgent discovery of new, effective, and affordable antibacterials with low toxicity is imperative to combat diverse MDR S. aureus strains. Hence, in this study, we introduce an in silico phytochemical-based approach for discovering novel antibacterial agents, underscoring the potential of computational approaches in therapeutic discovery. Glucomoringin Isothiocyanate (GMG-ITC) from Moringa oleifera Lam. is one of the phytochemical compounds with several biological activities, including antimicrobial, anti-inflammatory, and antioxidant activities, and is also effective against S. aureus. This study focuses on screening GMG-ITC as a potential drug candidate to combat MDR S. aureus infections through a molecular docking approach. Moreover, interaction amino acid analysis, in silico pharmacokinetics, compound target prediction, pathway enrichment analysis and molecular dynamics (MD) simulations were conducted for further investigation. Molecular docking and interaction analysis showed strong binding affinity towards S. aureus lipase, dihydrofolate reductase, and other MDR S. aureus proteins, including penicillin-binding protein 2a, MepR, D-Ala:D-Ala ligase, and RPP TetM, through hydrophilic and hydrophobic interactions. GMG-ITC also showed a strong binding affinity to cyclooxygenase-2 and FAD-dependent NAD(P)H oxidase, suggesting that it is a potential anti-inflammatory and antioxidant candidate that may eliminate inflammation and oxidative stress associated with S. aureus infections. MD simulations validated the stability of the GMG-ITC molecular interactions determined by molecular docking. In silico pharmacokinetic analysis highlights its potency as a drug candidate, showing strong absorption, distribution, and excretion properties in combination with low toxicity. It acts as an active protease and enzyme inhibitor with moderate activity against GPCR ligands, ion channels, nuclear receptor ligands, and kinases. Enrichment analysis further elucidated its involvement in important biological, molecular, and cellular functions with potential therapeutic applications in diseases like cancer, hepatitis B, and influenza. Results suggest that GMG-ITC is an effective antibacterial agent that could treat MDR S. aureus-associated infections.

Coumarin derivatives ameliorate the intestinal inflammation and pathogenic gut microbiome changes in the model of infectious colitis through antibacterial activity.

Coumarin, a phenolic compound, is a secondary metabolite produced by plants such as Tanga and Lime. Coumarin derivatives were prepared via Pechmann condensation. In this study, we performed in vitro and in vivo experiments to determine the antimicrobial and gut immune-regulatory functions of coumarin derivatives. For the in vitro antimicrobial activity assay, coumarin derivatives C1 and C2 were selected based on their pathogen-killing activity against various pathogenic microbes. We further demonstrated that the selected coumarin derivatives disrupted bacterial cell membranes. Next, we examined the regulatory function of the coumarin derivatives in gut inflammation using an infectious colitis model. In an in vivo infectious colitis model, administration of selected C1 coumarin derivatives reduced pathogen loads, the number of inflammatory immune cells (Th1 cells and Th17 cells), and inflammatory cytokine levels (IL-6 and IL-1b) in the intestinal tissue after pathogen infection. In addition, we found that the administration of C1 coumarin derivatives minimized abnormal gut microbiome shift-driven pathogen infection. Potential pathogenic gut microbes, such as Enterobacteriaceae and Staphylococcaceae, were increased by pathogen infection. However, this pathogenic microbial expansion was minimized and beneficial bacteria, such as Ligilactobacillus and Limosilactobacillus, increased with C1 coumarin derivative treatment. Functional gene enrichment assessment revealed that the relative abundance of genes associated with lipid and nucleotide metabolism was reduced by pathogen infection; however, this phenomenon was not observed in C1 coumarin derivative-treated animals. Collectively, our data suggest that C1 coumarin derivative is effective antibacterial agents that minimize pathogen-induced gut inflammation and abnormal gut microbiome modulation through their antibacterial activity.

A Review of Plant-Mediated ZnO Nanoparticles for Photodegradation and Antibacterial Applications.

This review focuses on the synthesis of plant-mediated zinc oxide nanoparticles (ZnO NPs) and their applications for antibacterial and photocatalytic degradation of dyes, thereby addressing the need for sustainable and eco-friendly methods for the preparation of NPs. Driven by the significant rise in antibiotic resistance and environmental pollution from dye pollution, there is a need for more effective antibacterial agents and photocatalysts. Therefore, this review explores the synthesis of plant-mediated ZnO NPs, and the influence of reaction parameters such as pH, annealing temperature, plant extract concentration, etc. Additionally, it also looks at the application of plant-mediated ZnO NPs for antibacterial and photodegradation of dyes, focusing on the influence of the properties of the plant-mediated ZnO NPs such as size, shape, and bandgap on the antibacterial and photocatalytic activity. The findings suggest that properties such as shape and size are influenced by reaction parameters and these properties also influence the antibacterial and photocatalytic activity of plant-mediated ZnO NPs. This review concludes that plant-mediated ZnO NPs have the potential to advance green and sustainable materials in antibacterial and photocatalysis applications.

Green synthesis and characterization of zinc oxide nanoparticles using Monoon longifolium leave extract for biological applications

The present study deals with the biosynthesis of zinc oxide nanoparticles (ZnO NPs) using the Monoonlongifolium (M. longifolium) leaf extract. The prepared ZnO NPs were characterized by XRD, FTIR, UV–Vis, TGA/DTA, and SEM. The synthesis parameters, such as plant extract volume (10–50 mL), heating duration (15 min), zinc nitrate concentration (1 mM), reaction time (1 h), and temperature (60 °C), were optimized. The synthesized ZnO NPs exhibited significant antibacterial activity against Staphylococcusaureus (22 ± 0.57 mm) and Escherichiacoli (19 ± 1 mm), as well as antifungal activity against Candidaalbicans (21 ± 0.16 mm), as determined by the agar-well-diffusion method. The minimum inhibitory concentration (MIC) of ZnO-NPs against S. aureus (6.25µg/mL) and E. coli (12.5 µg/mL), respectively, while the minimum fungicidal concentration (MFC) was 25 µg/mL against Candidaalbicans. Additionally, the antioxidant activity of the ZnO NPs ranged from 0 to 78% (IC50 = 12.5 μg/mL). These results demonstrate the potential of the synthesized ZnO NPs as effective antibacterial, antifungal, and antioxidant agents.

An investigation of silver nanoparticles made from plectranthus amboinicus leaves and their antibacterial and photocatalytic activities

In the present research, silver nanoparticles (AgNPs) were prepared utilizing Plectranthus amboinicus using a simple green synthesis process. UV, FT-IR, XRD, TEM, SEM, EDX and DLS were used to characterize the prepared AgNPs. The SPR band appears at 448 nm in the UV–visible spectrum. The FTIR spectrum of the synthesized materials confirmed the presence of potential functional groups in the P.amboinicus leaf extract, as well as silver nanoparticles. The peaks in the PXRD is indexed with the database entry (110) reveals the crystalline nature and the FCC structures of silver nanoparticles. The SEM image reveals the existence of spherical shaped AgNPs, while the EDX image reveals the presence of silver element. TEM pictures indicate the spherical shape of AgNPs with sizes ranging from 20 to 30 nm. Additionally, these biosynthesized NPs photocatalytic activity was investigated against methylene blue under sun irradiation, and after 60 min of exposure, they demonstrated an efficiency of 94 %.Furthermore, the most effective antibacterial agent is Pseudomonas aeruginosa, as evidenced by a 14 mm AgNPs inhibition zone. As a result, we conclude that the synthesized Plectranthus amboinicus AgNPs have more medicinal and industrial potential.

Machine Learning Prediction of Small Molecule Accumulation in Escherichia Coli Enhanced with Descriptor Statistics.

Antibiotic resistance, particularly among Gram-negative bacteria, poses a significant healthcare challenge due to their ability to evade antibiotic action through various mechanisms. In this study, we explore the prediction of small molecule accumulation in Gram-negative bacteria by using machine learning techniques enhanced with statistical descriptors derived from molecular dynamics simulations. We begin by identifying a minimal set of molecular descriptors that maximize the model's predictive power while preserving human interpretability. We optimize model accuracy, precision, and the area under the receiver operating characteristic curve through an iterative process. We demonstrate that the inclusion of statistical descriptors significantly improves model performance across various prediction metrics. Particularly, the addition of statistical descriptors related to dipole moment and minimum projection radius enhances the model's predictive capabilities, shedding light on the physicochemical properties crucial for small molecule accumulation. Our findings highlight the importance of considering statistical moments beyond mean values in predictive modeling and suggest avenues for future research. Overall, our study provides insights into the complex dynamics of antibiotic accumulation in Escherichia coli bacterial cells, generalizable to other Gram-negative species, offering a promising approach for the discovery of effective antibacterial agents, identifying new hits, and improving them to define effective lead agents.

Novel trans-Resveratrol Derivatives: Design, Synthesis, Antibacterial Activity, and Mechanisms.

Rice bacterial leaf blight and rice bacterial leaf streak have induced tremendous damage to production of rice worldwide. To discover an effective novel antibacterial agent, a series of novel trans-resveratrol (RSV) derivatives containing 1,3,4-oxadiazole and amide moieties were designed and synthesized for the first time. Most of them showed excellent antibacterial activities against Xanthomonas oryzae pv oryzicola and Xanthomonas oryzae pv oryzae. Especially, compound J12 had the best inhibitory with the half-maximal effective concentration values of 4.2 and 5.0 mg/L, respectively, which were better than that of RSV (63.7 and 75.4 mg/L), bismerthiazol (79.5 and 89.6 mg/L), and thiodiazole copper (105.4 and 112.8 mg/L). Furthermore, compound J12 had an excellent control effect against rice bacterial leaf streak and rice bacterial leaf blight, with protective activities of 46.2 and 42.1% and curative activities of 44.5 and 41.7%, respectively. Preliminary mechanisms indicated that compound J12 could not only remarkably decrease biofilm formation, extracellular polysaccharide production, and the synthesis of extracellular enzymes but also destroy bacterial cell surface morphology, thereby reducing the pathogenicity of bacteria. In addition, compound J12 could increase the activity of defense-related enzymes and affect the expression of multiple pathogenic-related genes including plant-pathogen interaction, the MAPK signaling pathway, and phenylpropanoid biosynthesis, and this could improve the defense of rice against rice bacterial leaf streak infection. The present work indicates that the RSV derivatives can be used as promising candidates for the development of antibacterial agents.

Mechanisms of action of berberine hydrochloride in planktonic cells and biofilms of Pseudomonas aeruginosa

The increasing prevalence of extensively drug-and pan-drug-resistant Pseudomonas aeruginosa is a major concern for global public health. Therefore, it is crucial to develop novel antimicrobials that specifically target P. aeruginosa and its biofilms. In the present study, we determined that berberine hydrochloride inhibited the growth of planktonic bacteria as well as prevented the formation of biofilms. Moreover, we observed downregulation in the expression of pslA and pelA biofilm-related genes. Compared with existing antibiotics, berberine hydrochloride exhibits multiple modes of action against P. aeruginosa. Our findings suggest that berberine hydrochloride exerts its antimicrobial effects by damaging bacterial cell membranes, generating reactive oxygen species (ROS), and reducing intracellular adenosine triphosphate (ATP) levels. Furthermore, berberine hydrochloride showed minimal cytotoxicity and reduced susceptibility to drug resistance. In a mouse model of peritonitis, it significantly inhibited the growth of P. aeruginosa and exhibited a strong bacteriostatic action. In conclusion, berberine hydrochloride is a safe and effective antibacterial agent that inhibits the growth of P. aeruginosa.

Biosynthesis of zinc oxide nanoparticles via neem extract and their anticancer and antibacterial activities.

In the present study, zinc oxide nanoparticles (ZnO-NPs) were synthesized using neem leaf aqueous extracts and characterized using transmission electron microscopy (TEM), ultraviolet visible spectroscopy (UV-Vis), and dynamic light scattering (DLS). Then compare its efficacy as anticancer and antibacterial agents with chemically synthesized ZnO-NPs and the neem leaf extract used for the green synthesis of ZnO-NPs. The TEM, UV-vis, and particle size confirmed that the developed ZnO-NPs are nanoscale. The chemically and greenly synthesized ZnO-NPs showed their optical absorbance at 328 nm and 380 nm, respectively, and were observed as spherical particles with a size of about 85 nm and 62.5 nm, respectively. HPLC and GC-MS were utilized to identify the bioactive components in the neem leaf aqueous extract employed for the eco-friendly production of ZnO-NPs. The HPLC analysis revealed that the aqueous extract of neem leaf contains 19 phenolic component fractions. The GC-MS analysis revealed the existence of 21 bioactive compounds. The antiproliferative effect of green ZnO-NPs was observed at different concentrations (31.25 µg/mL-1000 µg/mL) on Hct 116 and A 549 cancer cells, with an IC50 value of 111 µg/mL for A 549 and 118 µg/mL for Hct 116. On the other hand, the antibacterial activity against gram-positive and gram-negative bacteria was estimated. The antibacterial result showed that the MIC of green synthesized ZnO-NPs against gram-positive and gram-negative bacteria were 5, and 1 µg/mL. Hence, they could be utilized as effective antibacterial and antiproliferative agents.

Green Synthesis of Silver Nanoparticles Using Plant Extract Blends and Its Impact on Antibacterial and Biological Activity

There is a strong interest in using green resources for synthesizing nanoparticles (NPs) of industrial and biomedical utility in a way to maintain desired material properties throughout use while not inducing any harmful effects. The use of various plant extracts as reducing, capping, or stabilizing agents is widely attempted in green nanotechnology. However, very little has been explored about incorporating plant extract blends into green NP synthesis routes. Here, we used the combination of tea and olive leaf extracts for the synthesis of silver NPs and evaluated the advantages it provided over both chemical and single-plant-mediated synthesis routes. Four different reducing agents (tannic acid, black tea leaves extract, olive leaves extract and their blend) were used to synthesize silver NPs (Ag NP) from silver nitrate (AgNO[Formula: see text]. The synthesized Ag NP was characterized by scanning electron microscopy (SEM), dynamic light scattering (DLS), and ultraviolet-visible (US-Vis) spectroscopy. The antimicrobial properties of Ag NP were assessed against Escherichia coli (E. Coli) and Staphylococcus aureus (S. Aureus) using the colony-forming unit (CFU) assay and the minimum inhibitory concentration (MIC) assay. The cytotoxic potential of Ag NP on human colorectal adenocarcinoma (Caco-2) cells was assessed by the WST-1 assay. Results showed that Ag NP synthesized using plant extract mixtures had a primary particle size of 40[Formula: see text]nm and were very effective antibacterial agents, with the MIC values ranging from [Formula: see text]g/mL to 10[Formula: see text][Formula: see text]g/mL. While the particle size obtained in chemical synthesis was slightly lower, the resultant Ag NP did not serve as an effective antibacterial agents at low doses. Further understanding of how best to integrate extracts of different plants into green NP synthesis routes will enable wider and safer biomedical applications.

Surface chemistry engineered selenium nanoparticles as bactericidal and immuno-modulating dual-functional agents for combating methicillin-resistant Staphylococcus aureus Infection

Because of the extremely complexed microenvironment of drug-resistant bacterial infection, nanomaterials with both bactericidal and immuno-modulating activities are undoubtedly the ideal modality for overcoming drug resistance. Herein, we precisely engineered the surface chemistry of selenium nanoparticles (SeNPs) using neutral (polyvinylpyrrolidone-PVP), anionic (letinan-LET) and cationic (chitosan-CS) surfactants. It was found that surface chemistry greatly influenced the bioactivities of functionalized SeNPs, their interactions with methicillin-resistant Staphylococcus aureus (MRSA), immune cells and metabolisms. LET-functionalized SeNPs with distinct metabolisms exhibited the best inhibitory efficacy compared to other kinds of SeNPs against MRSA through inducing robust ROS generation and damaging bacterial cell wall. Meanwhile, only LET-SeNPs could effectively activate natural kill (NK) cells, and enhance the phagocytic capability of macrophages and its killing activity against bacteria. Furthermore, in vivo studies suggested that LET-SeNPs treatment highly effectively combated MRSA infection and promoted wound healing by triggering much more mouse NK cells, CD8+ and CD4+ T lymphocytes infiltrating into the infected area at the early stage to efficiently eliminate MRSA in the mouse model. This study demonstrates that the novel functionalized SeNP with dual functions could serve as an effective antibacterial agent and could guide the development of next generation antibacterial agents.

Antibacterial mechanism of Pseudomonas aeruginosa UKMP14T rhamnolipids against multidrug resistant Acinetobacter baumannii

Rhamnolipids, a major category of glycolipid biosurfactant, have recently gained enormous attention in medical field because of their relevance as effective antibacterial agents against a wide variety of pathogenic bacteria. Our previous studies have shown that rhamnolipids from an environmental isolate of Pseudomonas aeruginosa UKMP14T possess antibacterial, anti-adhesive and anti-biofilm activity against multidrug-resistant ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa and Enterobacter sp.) pathogens. However, the mechanism of their antibacterial action remains unclear. Thus, this study aimed to elucidate the mechanism of the antibacterial action of P. aeruginosa UKMP14T rhamnolipids by studying the changes in cells of one of the ESKAPE pathogens, Acinetobacter baumannii, which is the most difficult strain to kill. Results revealed that rhamnolipid treatment rendered A. baumannii cells more hydrophobic as evaluated through contact angle measurements. It also induced the release of cellular proteins measuring 510 μg/mL at a rhamnolipid concentration of 1000 μg/mL. In addition, rhamnolipids were found to be bactericidal in their action as they could permeate the inner membranes, leading to a leak-out of nucleotides. More than 50 % of the cells were found to be killed upon 1000 μg/mL rhamnolipid treatment as observed through fluorescence microscopy. Other cellular changes such as irregular shape and size, membrane perturbations, clumping, shrinkage and physical damage were clearly visible in SEM, FESEM and laser micrographs. Furthermore, rhamnolipid treatment inhibited the levels of acyl-homoserine lactones (AHLs) in A. baumannii, which are vital for their biofilm formation and virulence. The obtained results indicate that P. aeruginosa UKMP14T rhamnolipids target outer and inner bacterial membranes through permeation, including physical damage to the cells, leading to cell leakage. Furthermore, AHL inhibition appears to be the mechanism behind their anti-biofilm action. All these observations can be correlated to rhamnolipids’ antibacterial effect against A. baumannii.

The Highly Durable Antibacterial Gel-like Coatings for Textiles.

Hospital-acquired infections are considered a priority for public health systems since they pose a significant burden for society. High-touch surfaces of healthcare centers, including textiles, provide a suitable environment for pathogenic bacteria to grow, necessitating incorporating effective antibacterial agents into textiles. This paper introduces a highly durable antibacterial gel-like solution, Silver Shell™ finish, which contains chitosan-bound silver chloride microparticles. The study investigates the coating's environmental impact, health risks, and durability during repeated washing. The structure of the Silver Shell™ finish was studied using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). The TEM images showed a core-shell structure, with chitosan forming a protective shell around groupings of silver microparticles. The field-emission scanning electron microscopy (FESEM) demonstrated the uniform deposition of Silver Shell™ on the surfaces of the fabrics. AATCC Test Method 100 was employed to quantitatively analyze the antibacterial properties of the fabrics coated with silver microparticles. Two types of bacteria, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), were used in this study. The antibacterial results showed that after 75 wash cycles, a 100% reduction for both S. aureus and E. coli in the coated samples using crosslinking agents was observed. The coated samples without a crosslinking agent exhibited 99.88% and 99.81% reductions for S. aureus and E. coli after 50 washing cycles. To compare the antibacterial properties toward non-pathogenic and pathogenic strains of the same species, MG1655 model E. coli strain (ATCC 29213) and a multidrug-resistant clinical isolate were used. The results showed the antibacterial efficiency of the Silver ShellTM solution (up to 99.99% reduction) coated on cotton fabric. AATCC-147 was performed to investigate the coated samples' leaching properties and the crosslinking agent's effects against S. aureus and E. coli. All coated samples demonstrated remarkable antibacterial efficacy, even after 75 wash cycles. The crosslinking agent facilitated durable attachment between the silver microparticles and cotton substrate, minimizing the release of particles from the fabrics. Color measurements were conducted to assess the color differences resulting from the coating process. The results indicated fixation values of 44%, 32%, and 28% following 25, 50, and 75 washing cycles, respectively.