Potent Antibacterial Activity Research Articles

Silver Nanoparticles as Antiviral and Antibacterial Agents: A Comprehensive Review of Synthesis Methods and Therapeutic Application

AbstractSilver nanoparticles have shown inhibitory capabilities and its use in battling viral infections are strengthened by its potent antibacterial activity. Notably, since it directly affects antiviral efficacy, the proper choice of synthesis process for making silver nanoparticles is a vital element to be taken into consideration. The synthesis of silver nanoparticles for the treatment of viral and bacterial infections involves creating silver particles at the nanoscale with unique antimicrobial properties. Various methods exist for synthesizing silver nanoparticles, including chemical reduction, green synthesis, and physical methods. Chemical reduction involves using reducing agents to convert silver ions into silver nanoparticles. Green synthesis employs reducing agents in an environmentally friendly manner. Physical methods rely on techniques such as laser ablation or thermal evaporation to produce silver nanoparticles. In order to provide technological guidance for choosing antiviral silver nanoparticle manufacturing methods, this paper introduces and explores alternative synthesis methods for creating silver nanoparticles.

Novel 9H‐flouren containing indoline scaffolds: Synthesis, characterization, antimicrobial assays, and molecular docking study

Abstract9H fluoren containing indoline scaffolds were developed by coupling indoline amine with α‐carboxylic acid group of amino acids in the presence of the peptide coupling reagent hexafluorophosphate benzotriazole tetramethyluronium (HBTU). All eight (12a–12h) synthesized indoline scaffolds were analyzed for their potent antibacterial and antifungal activities. The antibacterial assay revealed that compounds 12a, 12b, and 12e have shown excellent activity against pathogenic strains Pseudomonas aeruginosa, Staphylococcus aureus, and Streptococcus pyogenes with minimum inhibitory concentration (MIC) values as low as between 25 and 125 μg/mL. The antifungal activity of all synthesized indoline scaffolds were moderate compared with used standard drugs. The molecular docking study of 12a, 12b, and 12e with various antibacterial target proteins from different bacterial strains revealed outstanding interactions which ultimately support antibacterial results.

Zinc caproate: Ecofriendly synthesis, structural characterization, and antibacterial action

Disease-causing microorganisms such as Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) are among the primary contributors to morbidity and mortality of diarrhea in humans. Considering the challenges associated with antibiotic use, including antimicrobial resistance, this study aimed to develop a novel zinc-based agent for bacterial inactivation. To this end, zinc caproate (ZnCA) was synthesized using caproic acid (CA) and zinc oxide (ZnO) in anhydrous ethanol via the solvothermal method. Structural characterization techniques, including Fourier-transform infrared spectroscopy, single crystal X-ray diffraction analysis, and nuclear magnetic resonance spectroscopy, revealed the bidentate bridging coordination of zinc atoms with CA. The resulting two-dimensional ZnCA network was found to be composed of a distinct lamellar pattern, without any evident inter-layer interactions. Powder X-ray diffraction analysis, elemental analysis, and melting point analysis confirmed that ZnCA had an average particle size of 1.320 µm, a melting point of 147.2 °C, and a purity exceeding 98 %. Remarkably, ZnCA demonstrated potent antibacterial activity against E. coli and S. aureus, which exceeded the antibacterial efficacy of ZnO. ZnCA exerted its antibacterial effects by inhibiting biofilm formation, disrupting cell membrane integrity, increasing cell membrane permeability, and altering intracellular Ca2+-Mg2+-ATPase activity. These findings highlight the potential of ZnCA as a promising antibiotic substitute for the treatment of diarrhea in humans.

Green synthesis of rice straw-derived silica nanoparticles by hydrothermal process for antimicrobial properties and effective degradation of dyes

Rice straw is considered a major agricultural waste that has become a major threat to the environment. However, waste valorization of rice straws is a major challenge for the whole world. Therefore, this research aimed to utilize the different varieties of rice straw including Parmal rice straw (PRS), and Basmati rice straw (BRS) for the synthesis of silica nanoparticles (SiNPs) using hydrothermal autoclave method to precisely modify the particle size, and distribution, morphology and purity. This method uses water as a reaction medium under high temperature and pressure, which results in energy savings and reduced chemical waste compared to traditional methods. Furthermore, SiNPs were characterized using different analytical techniques. SEM showed the rough, compact, and highly ordered surface for both samples, while the SNP exhibited irregular shapes and rough surfaces. Rice straw powder revealed major functional groups at 787 cm−1, 1461 cm−1, and 2919.10 cm−1. BRS and PRS showed thermal stability up to 380 ℃ and 250 ℃, respectively. The particle size of BRS and PRS were found to be 112.47±1.23 nm and 114.98±1.23 nm, respectively. PRS-SiNPs showed the effective dye reduction ability for anthraquinone (96.79%± 0.39) and alizarin yellow (92.63%± 0.17) in 30 min. Additionally, the SiNPs exhibited potential bactericidal activity against Staphylococcus aureus and Escherichia coli in terms of zone of inhibition. Overall, the SiNPs synthesized from PRS demonstrated superior photocatalytic efficiency in the reduction of dyes compared to those synthesized from BRS.

Synthesis, characterization and Antibacterial Evaluation of Novel Thiazolidine Derivatives

Background: Heterocyclic compounds, which incorporate atoms such as nitrogen and sulfur alongside carbon, play a crucial role in nature and organic chemistry. Thiazolidine derivatives, characterized by sulfur and nitrogen atoms with a carbonyl group at the -4 position, are particularly noteworthy for their stability and diverse biological activities. We synthesized novel thiazolidine derivatives and determined their antibacterial properties. the synthesis of novel thiazolidine compounds was perforemd using thioglycolic acid with hydrazides, generated from the combination of hydrazides with benzaldehyde. Methods: The esters, hydrazides, hydrazones, and thiazolidines, were synthesized and characterized using infrared spectroscopy, nuclear magnetic resonance, and melting point analysis. Assessment of anti-bacterial activity was carried out against Gram-positive and Gram-negative bacterial strain of Staphylococcus aureus, Acinetobacter baumannii, Aeromonas sobria, and Escherichia coli. . Results: We synthesized ethyl 2-acetate (benzo[d]thiazol-2-yloxy), followed by the formation of 2-(benzo[d]thiazol-2-yloxy)acetohydrazide (hydrazide) through the reaction of this acetate with hydrazine. 16 compounds were synthesized with rigorous validation at each stage through spectral analysis. Thiazolidine derivatives exhibited promising inhibitory effects against bacterial growth, indicating their potential as antibacterial agents.Compound SH8 exhibited moderate to strong inhibitory effects against all tested species, notably Aeromonas sobria and Staphylococcus aureus, at a concentration of 0.1 mg/ml. Conclusion: In conclusion, the synthesized compounds exhibited both structural integrity and potent antibacterial activity, suggesting avenues for further exploration in pharmaceutical research.

Synthesis, characterization and Antibacterial Evaluation of Novel 1,3-Oxazepine Derivatives Using A Cycloaddition Approach

This study demonstrated the synthesis and characterization of novel heterocyclic compounds, particularly oxazepine derivatives, using a cycloaddition procedure. The synthesis involved the reaction of chloroacetohydrazide with various aromatic aldehydes under acidic conditions in ethanol solvent to produce hydrazone compounds. These hydrazones subsequently underwent pericyclic synthesis with phthalic anhydride to yield oxazepine derivatives. The physicochemical properties of the synthesized compounds (F1 to F13) were characterized using FT-IR and H-NMR spectroscopy. The antibacterial activity of the synthesized oxazepine derivatives (F8, F9, F10, F11, F12, and F13) was evaluated against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacterial strains using the cup plate agar diffusion technique. Notably, compounds F8, F9, and F10 exhibited potent antibacterial activity against both Gram-positive and Gram-negative bacteria, suggesting their potential as effective antibacterial agents. Molecular docking studies were also conducted to investigate the binding interactions of selected compounds with bacterial protein receptors, specifically Escherichia coli K-12 (PDB ID: 4QGS) and Staphylococcus aureus (PDB ID: 7PQ1). The results demonstrate the potential of these novel oxazepine derivatives as antibacterial agents, highlighting their promising biological activities and molecular interactions with bacterial proteins.

Short Communication: Evaluation of antibacterial activities and phytochemical composition of ethanolic extract of Diplazium esculentum

Abstract. Alamsjah F, Fandini S, Mildawati M. 2024. Short Communication: Evaluation of antibacterial activities and phytochemical composition of ethanolic extract of Diplazium esculentum. Biodiversitas 25: 937-941. Antibacterial agents are crucial in fighting infections by stopping or inhibiting pathogenic bacteria growth. Diplazium esculentum (Retz.) Sw., is a natural resource with great potential in traditional medicine. This study aimed to investigate the antibacterial effectiveness of ethanol extract of D. esculentum against two common bacteria, Pseudomonas aeruginosa and Staphylococcus epidermidis. This research was done using disc diffusion technique with comprehensive phytochemical screening. The results revealed antibacterial properties of the ethanolic extract of D. esculentum against P. aeruginosa and S. epidermidis. The most potent antibacterial activity was observed at 80 and 60% concentrations against P. aeruginosa, resulting in inhibition zones with 5.90 mm and 5.47 mm diameters. A similar pattern was also observed against S. epidermidis, where 80% concentration showed significant efficacy, with an inhibition zone of 5.69 mm diameter. Phytochemical analysis result revealed the presence of various secondary metabolites, including alkaloids, steroids, polyphenols, tannins, flavonoids, and saponins. These phytochemical compounds contribute antibacterial properties and have promising potential for further research to develop natural antibacterial agents.

A comparative study on the chemical composition, anti-microbial, antiparasitic, and cytotoxic activities of Rhanterium adpressum Coss. & Dur. and Rhanterium suaveolens Desf. essential oils from Algeria

The aim of the present study was to evaluate and compare the chemical composition, antimicrobial, antiparasitic, and cytotoxic properties of the essential oils extracted from Rhanterium adpressum Coss. & Dur. (EORA) and Rhanterium suaveolens Desf. (EORS). The main compounds of EORA were myrcene (18.51%), α-pinene (14.36%), sabinene (13.55%), β-pinene (5.67%), and camphene (5.39%). While camphene (25.06%), α-pinene (13.14%), myrcene (9.74%), sabinene (8.27%), D-limonene (7.86%), and β-pinene (7.34%) constituted the major components of EORS. A potent antibacterial activity was also recorded against Escherichia coli with MIC = 5.72 mg/mL for EORA and MIC = 5.96 mg/mL for EORS. Concerning the antifungal effect, a remarkable efficiency was exerted against the two tested Candida albicans strains (MIC < 5.96 mg/mL) for EORS and against Candida albicans 26 (MIC = 5.72 mg/mL) for EORA. Furthermore, a promising antiparasitic ability was observed against Acanthamoeba castellanii (IC50 = 6.42±0.21 μg/mL) for EORS and against Leishmania amazonensis (IC50=9.66±1.46 μg/mL) for EORA. However, low cytotoxicity was recorded against macrophages J774-A1 (LC50 = 67.68±4.02 μg/mL) only for EORS. Based on the present findings, it may be concluded that the two tested EOs possess significant antimicrobial and antiparasitic activities with minimal cytotoxicity, so they can be used as new sources of antimicrobial and antiparasitic drugs.

Studies on Ulva fasciata and Chaetomorpha antennina from Tenneti Park, Visakhapatnam Coastal Area, India

Seaweed is considered as herbal medicine and food source utilized by the coastal community. Seaweed is commonly consumed because it is an important source of iodine. Ulva fasciata and Chaetomorpha antennina are green seaweed wildly grow in marine environment. Green algae are involved in photosynthetic reaction. These are observed worldwide. These algal blooms are a consequence of human activities. Phytochemical compounds are secondary metabolite groups in living organisms that have a certain function for humans. Algae are known to contain a huge variety of bioactive compounds having high potentiality towards medical field. They are seen mainly in shallow waters with high degree of salinity. Now-a-days they have commercially important with their valuable components in the form of as bioactive compounds. The objective of this study was to analyse the potential anti-bacterial activity and antifungal activity, the presence of phytochemical and biomolecules in U. fasciata and C. antennina. The samples of U. fasciata and C. antennina was collected aseptically from Tenneti park, Visakhapatnam coastal zone. The research phase includes solvent extraction, phytochemical screening, and antibacterial activity. The zone of inhibition ranges from 0.5nm to 0.7nm by the U. fasciata extracts whereas the extracts from C. antennina ranges from 0.2nm to 0.3 nm. The presence of phytochemicals was observed in both the green seaweeds. The present study is biofuel extraction from the 2 seaweed extracts. The findings gave a result that C. antennina have high potentiality of biofuel production.

Modification and characterization of tricalcium silicate bio-ceramic powders synthesized by sol-gel process for potential application in dental treatment

Tricalcium silicate powders (Ca3SiO5 or C3S) were fabricated by sol-gel process from the initial materials of Ca(NO3)2·4 H2O and Si(OC2H5)4 (TEOS) in acid medium. Effects of stoichiometry of reagent and catalyst, and temperature on physical-chemical, mechanical, and biological properties of C3S powders were examined systematically. The radiopacity, setting time, compressive strength, and bioactivity were investigated according to ISO recommendations. The radiopacity was compared and evaluated using dopants. The setting time and compressive strength were determined using water solvent. Analysis of bioactivity, antibacterial activity, and biocompatibility of Ca3SiO5 powders was performed and evaluated using simulated body fluid (SBF), and Tetrazolium (WST-1) reagent assay on Escherichia coli bacterium (E. coli), respectively. The milled-C3S powders showed a fine radiopacity with ZrO2 dopant, a shorter setting time, a higher density and a feasible compressive strength. The high purity of the milled-C3S powders with presence of Ca and Si compositions was confirmed by SEM-EDS analysis. Also, hydroxyapatite (HAp) was induced to form on the surface of milled-C3S powders when immersed in SBF. The surface compositional, morphological and chemical structural changes of the milled-C3S powders before and after immersing were analyzed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results showed that a dense HAp layer was formed after 7 days of immersing. It indicated that C3S powders were bioactive and might be used for preparation of dental biomaterials. The milled-C3S powders also showed a potential antibacterial activity on the E.Coli cells and a high biocompatibility for cell viability. The good physical and excellent mechanical properties, bioactivity, and antibacterial activity confirmed the milled-Ca3SiO5 powders as a promising dental filling material.

Antibacterial activity of nonantibiotics is orthogonal to standard antibiotics.

Numerous nonantibiotic drugs have potent antibacterial activity and can adversely affect the human microbiome. The mechanistic underpinning of this toxicity remains largely unknown. We investigated the antibacterial activity of 200 drugs using genetic screens with thousands of barcoded Escherichia coli knockouts. We analyzed 2 million gene-drug interactions underlying drug-specific toxicity. Network-based analysis of drug-drug similarities revealed that antibiotics clustered into modules that are consistent with the mode of action of their established classes, whereas nonantibiotics remained unconnected. Half of the nonantibiotics clustered into separate modules, potentially revealing shared and unexploited targets for new antimicrobials. Analysis of efflux systems revealed that they widely affect antibiotics and nonantibiotics alike, suggesting that the impact of nonantibiotics on antibiotic cross-resistance should be investigated closely in vivo.

Unraveling Multicopper [Cu3] and [Cu6] Clusters with Rare μ3-Sulfato and Linear μ2-Oxido-Bridges as Potent Antibiofilm Agents against Multidrug-Resistant Staphylococcus aureus.

In this research article, two multicopper [Cu3] and [Cu6] clusters, [Cu3(cpdp)(μ3-SO4)(Cl)(H2O)2]·3H2O (1) and [Cu6(cpdp)2(μ2-O)(Cl)2(H2O)4]·2Cl (2) (H3cpdp = N,N'-bis[2-carboxybenzomethyl]-N,N'-bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol), have been explored as potent antibacterial and antibiofilm agents. Their molecular structures have been determined by a single-crystal X-ray diffraction study, and the compositions have been established by thermal and elemental analyses, including electrospray ionization mass spectrometry. Structural analysis shows that the metallic core of 1 is composed of a trinuclear [Cu3] assembly encapsulating a μ3-SO42- group, whereas the structure of 2 represents a hexanuclear [Cu6] assembly in which two trinuclear [Cu3] motifs are exclusively bridged by a linear μ2-O2- group. The most striking feature of the structure of 2 is the occurrence of an unusual linear oxido-bridge, with the Cu3-O6-Cu3' bridging angle being 180.00°. Whereas 1 can be viewed as an example of a copper(II)-based compound displaying a rare μ3:η1:η1:η1 bridging mode of the SO42- group, 2 is the first example of any copper(II)-based compound showing an unsupported linear Cu-O-Cu oxido-bridge. Employing variable-temperature SQUID magnetometry, the magnetic susceptibility data were measured and analyzed exemplarily for 1 in the temperature range of 2-300 K, revealing the occurrence of antiferromagnetic interactions among the paramagnetic copper centers. Both 1 and 2 exhibited potent antibacterial and antibiofilm activities against methicillin-resistant Staphylococcus aureus (MRSA BAA1717) and the clinically isolated culture of methicillin-resistant S. aureus (MRSA CI1). The mechanism of antibacterial and antibiofilm activities of these multicopper clusters was investigated by analyzing and determining the intracellular reactive oxygen species (ROS) generation, lipid peroxidation, microscopic observation of cell membrane disruption, membrane potential, and leakage of cellular components. Additionally, 1 and 2 showed a synergistic effect with commercially available antibiotics such as vancomycin with enhanced antibacterial activity. However, 1 possesses higher antibacterial, antibiofilm, and antivirulence actions, making it a potent therapeutic agent against both MRSA BAA1717 and MRSA CI1 strains.

Nanoclay Hydrogel Microspheres with a Sandwich-Like Structure for Complex Tissue Infection Treatment.

Addressing complex tissue infections remains a challenging task because of the lack of effective means, and the limitations of traditional bioantimicrobial materials in single-application scenarios hinder their utility for complex infection sites. Hence, the development of a bioantimicrobial material with broad applicability and potent bactericidal activity is necessary to treat such infections. In this study, a layered lithium magnesium silicate nanoclay (LMS) is used to construct a nanobactericidal platform. This platform exhibits a sandwich-like structure, which is achieved through copper ion modification using a dopamine-mediated metallophenolic network. Moreover, the nanoclay is encapsulated within gelatin methacryloyl (GelMA) hydrogel microspheres for the treatment of complex tissue infections. The results demonstrate that the sandwich-like micro- and nanobactericidal hydrogel microspheres effectively eradicated Staphylococcus aureus (S. aureus) while exhibiting excellent biocompatibility with bone marrow-derived mesenchymal stem cells (BMSCs) and human umbilical vein endothelial cells (HUVECs). Furthermore, the hydrogel microspheres upregulated the expression levels of osteogenic differentiation and angiogenesis-related genes in these cells. In vivo experiments validated the efficacy of sandwich-like micro- and nanobactericidal hydrogel microspheres when injected into deep infected tissues, effectively eliminating bacteria and promoting robust vascular regeneration and tissue repair. Therefore, these innovative sandwich-like micro- and nanobacteriostatic hydrogel microspheres show great potential for treating complex tissue infections.

Design, Synthesis, and Biological Evaluation of 5-(5-Iodo-2-isopropyl-4-methoxyphenoxy)pyrimidine-2,4-diamine (AF-353) Derivatives as Novel DHFR Inhibitors against Staphylococcus aureus.

The high lethality of Staphylococcus aureus infections and the emergence of antibiotic resistance make the development of new antibiotics urgent. Our previous work identified a hit compound h1 (AF-353) as a novel Mycobacterium tuberculosis (Mtb) dihydrofolate reductase (DHFR) inhibitor. Herein, we analyzed the antimicrobial profile of h1 and performed a comprehensive structure-activity relationship (SAR) assay based on h1. The representative compound j9 exhibited potent antibacterial activity against S. aureus without cross-resistance to other antimicrobial classes. Multiple genetic and biochemical approaches showed that j9 directly binds to SaDHFR, resulting in strong inhibition of its enzymatic activity (IC50 = 0.97 nM). Additionally, j9 had an acceptable in vivo safety profile and oral bioavailability (F = 40.7%) and also showed favorable efficacy in a mouse model of methicillin-resistant S. aureus (MRSA) skin infection. Collectively, these findings identified j9 as a novel SaDHFR inhibitor with the potential to combat drug-resistant S. aureus infections.

Efflux pump inhibitor, phenylalanine-arginine beta-naphthylamide analog potentiates the activity of 5-O-mycaminosyltylonolide for multi-drug resistant Pseudomonas aeruginosa.

The emergence and spread of antimicrobial resistance are global threats. Pseudomonas aeruginosa (P. aeruginosa) is responsible for a substantial proportion of this global health issue because of its intrinsic resistance to many antibiotics due to the impermeability of its outer membrane and its multidrug efflux pump systems. Therefore, therapeutic drugs are limited, and the development of new drugs is extremely challenging. As an alternative approach, we focused on a combinational treatment strategy and found that 5-O-mycaminosyltylonolide (OMT) showed potent antibacterial activity against P. aeruginosa in the presence of an efflux pump inhibitor, phenylalanine-arginine beta-naphthylamide (PAβN). In this report, we prepared a PAβN derivative and compared the potentiation activity of OMT by PAβNs against multidrug-resistant P. aeruginosa clinical isolates.

Monodispersed nanorod-shaped Mn-Co co-doped ZnO nanoparticles for enhanced photocatalytic and antibacterial activities

The present work deals with synthesizing the pure ZnO (PZ), manganese-doped ZnO (MZ), and manganese-cobalt co-doped ZnO (MCZ) nanoparticles by hydrothermal method. X-ray diffraction confirms their hexagonal wurtzite structure with varying crystallite sizes: 43.8 nm for PZ, 34.6 nm for MZ, and 27.6 nm for MCZ. The band gap values were calculated as 3.14 eV (PZ), 3.09 eV (MZ), and 2.89 eV (MCZ) from Tauc plot. FTIR analysis provided the evidence of metal–oxygen bonds and other characteristic functionalities. These nanoparticles exhibited potent antibacterial activity against both gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. In photocatalytic performance of MCZ has showed a higher rate of Crystal Violet dye degradation under visible light irradiation compared to other materials.

Antibacterial activity of cinnamon essential oil and its main component of cinnamaldehyde and the underlying mechanism.

Background: Plant essential oils have long been regarded as repositories of antimicrobial agents. In recent years, they have emerged as potential alternatives or supplements to antimicrobial drugs. Although literature reviews and previous studies have indicated that cinnamon essential oil (CIEO) and its major component, cinnamaldehyde (CID), possess potent antibacterial activities, their antibacterial mechanisms, especially the in vivo antibacterial mechanisms, remain elusive. Methods: In this study, we utilized the in vivo assessment system of Caenorhabditis elegans (C. elegans) to investigate the effects and mechanisms of high dose (100mg/L) and low dose (10mg/L) CIEO and CID in inhibiting Pseudomonas aeruginosa (P. aeruginosa). In addition, we also examined the in vitro antibacterial abilities of CIEO and CID against other common pathogens including P. aeruginosa and 4 other strains. Results: Our research revealed that both high (100mg/L) and low doses (10mg/L) of CIEO and CID treatment significantly alleviated the reduction in locomotion behavior, lifespan, and accumulation of P. aeruginosa in C. elegans infected with the bacteria. During P. aeruginosa infection, the transcriptional expression of antimicrobial peptide-related genes (lys-1 and lys-8) in C. elegans was upregulated with low-dose CIEO and CID treatment, while this trend was suppressed at high doses. Further investigation suggested that the PMK-1 mediated p38 signaling pathway may be involved in the regulation of CIEO and CID during nematode defense against P. aeruginosa infection. Furthermore, in vitro experimental results also revealed that CIEO and CID exhibit good antibacterial effects, which may be associated with their antioxidant properties. Conclusion: Our results indicated that low-dose CIEO and CID treatment could activate the p38 signaling pathway in C. elegans, thereby regulating antimicrobial peptides, and achieving antimicrobial effects. Meanwhile, high doses of CIEO and CID might directly participate in the internal antimicrobial processes of C. elegans. Our study provides research basis for the antibacterial properties of CIEO and CID both in vivo and in vitro.

Evaluation of antibacterial activity of an experimental dental adhesive containing synthesized quaternary ammonium compound: in vitro study

BackgroundDental adhesives with immobilized antibacterial agents are formulated to combat bacterial invasion along the tooth-restoration interface. This study aims to evaluate the antibacterial effect of synthesized quaternary ammonium compound (QAC) incorporated into commercial dental adhesive.MethodsQAC was synthesized from 2-(Dimethylamino) ethyl methacrylate and 1-Bromobutane and characterized using CHN (Carbon, Hydrogen, Nitrogen), FTIR (Fourier transform infrared) and H+NMR (Proton nuclear magnetic resonance) analyses. The synthesized QAC was assessed for its cytotoxicity and its antibacterial activity against S. mutans using disc diffusion method, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), time-kill kinetics test, and TEM imaging. The QAC was added to the primer of a commercially available adhesive (OptiBond XTR) at two concentrations; 20 and 40 mg mL−1 representing the MIC and MBC, respectively. The antibacterial properties of the experimental adhesives, commercial antibacterial adhesive Clearfil SE Protect containing 12-methacryloyloxydodecylpyridinium bromide (MDPB), and commercial vehicle (OptiBond XTR) were compared using time-kill kinetics test. Statistical analysis by ANOVA followed by tukey post-hoc test (P < 0.05).ResultsDisc diffusion and time-kill kinetics tests showed potent antibacterial action of QAC, both in the unpolymerized and the cured forms. MIC and MBC were 20 and 40 mg mL−1 respectively. There was no statistically significant difference between experimental adhesives and Clearfil Protect with more than 99% reduction in bacterial count, while OptiBond XTR showed no bacterial killing up for up to 10 h.ConclusionsThe synthesized QAC added to a commercially available adhesive imparted antibacterial properties, thus providing an affordable adhesive system to the local market.

Enhancing aquaculture management: Utilizing cu-doped ZnO/graphene nanocomposite for effective reduction of antibiotics and antibiotic-resistant Bacteria in shrimp culturing ponds

Shrimp culturing ponds, and enclosed breeding environments, contribute to the dissemination of antibiotics and antibiotic-resistant bacteria (ARBs) in aquatic ecosystems. This study focuses on the synthesis of a ternary nanocomposite photocatalyst, comprising Cu-doped ZnO and reduced graphene oxide (GP), using a one-step microwave-assisted hydrothermal method. The photocatalyst was employed to effectively eliminate antibiotics and inactive ARBs from aquaculture water. The structure, morphologies, and optical properties of the synthesized composites were investigated. Tetracycline (TET) and florfenicol (FLO) were the most frequently detected antibiotics in shrimp pond water, followed by sulfamethoxazole and tiamulin. Photo-degradation efficiency of TET and FLO using composite significantly improved under both UV and simulated solar irradiation. After 60 and 180 min of irradiation, the removal percentages for TET were 87.5% and 80.3%, while for FLO they were 89.5% and 92.1% respectively. The Cu-ZnO/GP composite demonstrates potent antibacterial activity against both Gram-positive (E. faecalis V583) and Gram-negative (E. coli K12 MG1655) antibiotic-resistant strains under light exposure. Its photocatalytic properties augment reactive oxygen species (ROS) generation, thereby enhancing bacterial inhibition. After 24 h of light exposure, E. coli growth was inhibited by 78%, while E. faecium growth was suppressed by 92%. The composite achieved the highest inactivation levels for E. coli (Ln-3.8) and E. faecalis (Ln-2.8) after 15 min of light exposure. The efficacy of Cu-ZnO/GP composite treatments in bacterial inactivation was notable in both ultrapure water (UPW) and real wastewater (RWW) matrices, achieving significant inactivation levels after a 1-h treatment. These findings underscore the potential of Cu-ZnO/GP composites to improve aquaculture management practices, thereby mitigating antibiotic proliferation in aquaculture waters and the surrounding environment.

Secondary Metabolites from Symbiotic Bacteria of Seagrass and Molluscs as A Reference for Natural Food Preservatives

Symbiotic bacteria from seagrass and molluscs have the potential to be a source of secondary metabolites. Compounds from these secondary metabolites, such as natural food preservatives, can be used in the bioindustry sector. This research aims to identify the potential secondary metabolites from symbiotic bacteria in molluscs and seagrass that can support the Sustainable Development Goals (SDG) public health program. The samples used in this study were symbiotic bacteria of mollusc from seagrass environments, symbiotic bacteria from seagrass, and seagrass samples. The seagrass samples were analysed phytochemically, while the symbiotic bacteria samples from molluscs and seagrass were tested for their antibacterial activity against food spoilage pathogens such as Staphylococcus aureus and Escherichia coli using the disc diffusion method. Bacteria that showed potential antibacterial activity were identified using molecular methods, and the content of active compounds was analysed using gas chromatography-mass spectrometry. The phytochemical analysis revealed that seagrass contains flavones, tannins, steroids, and compounds with potential antibacterial properties. GC-MS analysis indicated that seagrass is predominantly composed of unsaturated fatty acids, which have antimicrobial effects by damaging bacterial cell membranes and disrupting the function of enzymes essential for growth and reproduction. Ten symbiotic bacteria isolates demonstrated proteolytic, cellulolytic, and lipolytic enzyme activity, suggesting their potential as antibacterial agents due to their ability to break down cell walls. Molecular identification of selected bacteria revealed the presence of mollusc symbionts, including Vibrio owensii, Bacillus paramycoides, and Pseudoalteromonas flavipulchra. The symbiotic bacteria found in seagrass in this study included Bacillus velezensis, Bacillus paramycoides, Nocardiopsis alba, Nocardiopsis alba, Bacillus tropicus, Lysinibacillus fusiformis, and Bacillus tropicus. GC-MS analysis of selected symbiotic bacteria from seagrass showed that the dominant compound components were phthalic acid, bis(7-methyl octyl) ester (25.18, 43.84, 35.55 %), and trimethoxy-3-piperidyl-2,2'-binaphthalene-1,1',4,4'-tetrone (36.36, 47.71, 64.48 %). In conclusion, seagrass and its symbiotic bacteria, as well as symbiotic bacteria from molluscs living in seagrass, have the potential to serve as antibacterial agents and can be used as references for food preservatives. HIGHLIGHTS    Seagrass and mollusc symbiotic bacteria produce secondary metabolites that have antimicrobial properties, making them suitable for food preservation The component that acts as an antibacterial agent is found in seagrass: Essential fatty acids, which can have antibacterial properties Symbiotic bacteria are microorganisms that live in mutualistic symbiosis with other organisms. The enzymatic activities of symbiotic bacteria can involve the production of enzymes that break down complex molecules into simpler molecules In food preservation, symbiotic bacteria, with their enzymatic activity, can be used as natural preservatives Using natural food preservatives derived from seagrass and mollusc symbiotic bacteria can contribute to a more sustainable and environmentally friendly approach to food preservation GRAPHICAL ABSTRACT