Effective Antibacterial Agent Research Articles

Xylella phage MATE 2: a novel bacteriophage with potent lytic activity against Xylella fastidiosa subsp. pauca

Xylella fastidiosa (Xf) is a major phytosanitary threat to global agricultural production. The complexity and difficulty of controlling Xf underscore the pressing need for novel antibacterial agents, i.e., bacteriophages, which are natural predators of bacteria. In this study, a novel lytic bacteriophage of Xf subsp. pauca, namely Xylella phage MATE 2 (MATE 2), was isolated from sewage water in southern Italy. Biological characterization showed that MATE 2 possessed a broad-spectrum of antibacterial activity against various phytobacteria within the family Xanthomonadaceae, a rapid adsorption time (10 min), and high resistance to a broad range of pH (4–10) and temperatures (4–60°C). Most importantly, MATE 2 was able to suppress the growth of Xf subsp. pauca cells in liquid culture for 7 days, demonstrating its potential as an effective antibacterial agent against Xf. The genomic and electron microscopy analyses revealed that MATE 2 is a new species tentatively belonging to the genus Carpasinavirus within the class Caudoviricetes, with an isometric capsid head of 60 ± 5 nm along with a contractile tail of 120 ± 7.5 nm. Furthermore, the high-throughput sequencing and de novo assembly generated a single contig of 63,695 nucleotides in length; representing a complete genome composed of 95 Open Reading Frames. Bioinformatics analysis performed on MATE 2 genome revealed the absence of lysogenic mediated genes, and genes encoding virulence factors, antibiotic resistance, and toxins. This study adds a new phage to the very short list of Xf-infecting lytic phages, whose in-vitro antibacterial activity has been ascertained, while its efficacy on Xf-infected olive trees in the field has yet to be determined.

Novel biaryloxazolidinone derivatives with broad-spectrum antibacterial activity, favorable drug-like profiles and in vivo efficacy against linezolid-resistant Staphylococcusaureus

The emergence of multidrug-resistant bacteria along with a declining pipeline of clinically useful antibiotics has led to the urgent need for the development of more effective antibacterial agents to treat drug-resistant bacteria. We previously discovered compound OB-158 with potent antibacterial activity but exhibited poor oral bioavailability. Herein, a systematic structural optimization of OB-158 to improve pharmacokinetic profiles yielded 26 novel biaryloxazolidinone analogues, and their activities against Gram-positive S. aureus, multidrug resistant S. aureus and Enterococcus faecalis were evaluated. Remarkably, compound 8b was identified with potent antibacterial activity against S. aureus (MIC=0.06μg/mL), MSSA (MIC=0.125μg/mL), MRSA (MIC=0.06μg/mL), LRSA (MIC=0.125μg/mL) and LREFa (MIC=0.5μg/mL). Compound 8b was demonstrated as a promising candidate through druglikeness evaluation including metabolism in microsomes and plasma, Caco-2cell permeability, plasma protein binding, cytotoxicity, and inhibition of CYP450 and human monoamine oxidase. Notably, compound 8b displayed excellent PK profile with appropriate T1/2 of 1.49h, high peak plasma concentration (Cmax=2320ng/mL), high plasma exposure (AUC0-t=8310hng/mL), and superior oral bioavailability (F=68.1%) in Sprague-Dawley rats. Ultimately, in vivo efficacy of compound 8b in a mouse model of LRSA systemic infection was also demonstrated. Taken together, compound 8b represents a promising drug candidate for the treatment of linezolid-resistant Gram-positive bacterial strains infection.

Biofabrication, Characterisation and Antimicrobial Activity of CuO/Ag-based Material

In this work, Azadirachta indica leaf extract and the ultrasonic method were applied for the fabrication of a CuO/Ag-based nanocomposite. The CuO/Ag was characterised using different analytical methods such as FTIR, SEM, EDX, and XRD. The well diffusion method was used to evaluate the antibacterial activity of non-calcined and calcined CuO/Ag against some hazardous bacterial strains. After the incubation period, remarkable zones of inhibition were observed around the loaded CuO/Ag. The maximum zones of inhibition were found to be 17.9 (± 0.39), 20 (± 0.17), and 14.3 (± 0.31) mm for E. coli, S. aureus, and S. enterica, respectively. Experimental findings indicated that non-calcined CuO/Ag was a more effective antibacterial agent as compared to calcined CuO/Ag.

Cu(dimethylbpy)2Cl]PF6 Complex as an Antibacterial Agent

Background: Antibiotic resistance is currently considered a major public health problem. This subject underscores the critical need for novel and enhanced antibacterial agents with a novel molecular structure and a new target to prevent cross-resistance. Copper exhibits antimicrobial properties by disrupting bacterial cell membranes and interfering with cellular processes. Copper complexes enhance these properties, offering improved stability and targeted antibacterial activity. Their ability to release copper ions can gradually enhance efficacy while minimizing toxicity. Therefore, investigating the antibacterial properties of new copper complexes is of significance. background: Antibiotic resistance is currently considered as a major public health problem. These subject underscores the critical need for novel and enhanced antibacterial agents with a novel molecular structure and a new target to prevent cross-resistance Methods: In this study, the antibacterial activity of [Cu(dimethylbpy)2Cl]PF6 complex was examined against several Gram-negative bacteria, Pseudomonas aeruginosa, Escherichia coli, klebsiella pneumoniae, salmonella typhi and Gram-positive bacteria Staphylococcus aureus and Micrococcus luteus by determining the minimum inhibitory concentration (MIC). The antibacterial activity of [Cu(dimethylbpy)2Cl]PF6 complex and Gentamicin (as standard compound) were determined using the microplate method. All concentrations were repeated three times. The minimum inhibitory concentration was determined both using the unaided eye and absorbance at 490 nm. Results: The [Cu(dimethylbpy)2Cl]PF6 complex showed higher antibacterial activity against Gram-positive bacteria than Gram-negative bacteria. Among the assayed bacterial strains, the complex was most effective against Micrococcus luteus and Staphylococcus aureus with MIC values of 100 and 250 μM, respectively. Conclusion: This complex displayed antimicrobial potential against some bacterial strains. Therefore, this complex may be used as an effective antibacterial agent in the treatment of infection caused by some bacterial strains, but further research is needed.

Fabrication of hydrophobic drug-loaded Zeolitic Imidazolate Framework-8 (ZIF-8) for enhanced anti-bacterial activity

Current study presents a novel approach for constructing small hydrophobic biomolecules embedded within zeolitic imidazolate framework-8 (ZIF-8) with exceptional antibacterial properties. In this method, ZIF-8 is synthesized from zinc acetate and 2-methylimidazole in the presence or absence of small hydrophobic bioactive molecules like rutin, rosmarinic acid, and morin. Scanning electron microscopy (SEM) analysis reveals that the synthesized ZIF-8 nanoparticles exhibit mostly hexagonal shape with size 200 nm which is further increased upon drug encapsulation. The synthesis of ZIF-8 and drug-loaded ZIF-8 is confirmed through FTIR, UV–vis spectroscopy, XRD, TGA, and EDX analyses. Zeta potential measurements show values ranging from -14.5 to -23.97 mV for both ZIF-8 and drug-loaded ZIF-8 nanoparticles. The drug loading content is determined to be 5 %, 9 %, and 16 % for morin, rutin, and rosmarinic acid, respectively. All the drug-loaded ZIF-8 formulations exhibit a pH-dependent drug release pattern, with maximal drug release observed at lower pH levels. Most importantly, these formulations demonstrate potent antibacterial activity against both Gram-positive (Enterococcus faecalis and Bacillus subtilis) and Gram-negative (Escherichia coli) bacterial strains. Specifically, ZIF-8/RUT exhibit maximum zone of inhibition (ZOI ∼ 51 mm) against all tested bacterial strains. ZIF-8/MOR and ZIF-8/RUT exhibit MIC values ranging from 2.0 to 3.0 mg/mL and MBC values from 6 to 9 mg/mL against all the tested bacteria. Among the formulations, ZIF-8/MOR and ZIF-8/RUT exhibit synergistic antibacterial effect, whereas ZIF-8/RMA possess less antibacterial potency against all the tested bacteria and mostly exhibit additive effect. Our findings suggest that these newly developed nano-formulations hold potential for the creation of highly effective antibacterial agents.

Synthesis, Characterization and Antibacterial Activity of Novel 2‐Oxo‐1,2‐dihydro‐1′H‐spiro[indoline‐3,2′‐quinazoline]‐4′‐carbohydrazones

AbstractTreatment of isatin with ammonia in methanol under reflux, followed by hydrazine substitution of the methoxy group afforded isamic hydrazide in up to 79 % yield. Subsequent condensation of isamic hydrazide with selected aromatic ketones and aldehydes gave access to novel 2‐oxo‐1,2‐dihydro‐1′H‐spiro[indoline‐3,2′‐quinazoline]‐4′‐carbohydrazones (4–11) in yields between 59 % and 74 %. Detailed structural analysis of synthesized compounds was done using spectroscopic techniques. Antibacterial screening of the hydrazone derivatives (4–11) demonstrated broad‐spectrum activity against evaluated bacterial strains, with inhibition zones ranging from 10 to 32 mm. Specifically, compound 9 exhibited superior activity compared to the standard streptomycin against various bacterial strains, including B. polymyxa (LIO), B. cereus (NCBI 6349), C. pyogenes (LIO), B. subtilis (NCBI 3610), S. aureus (NCBI 8588), E. coli (NCIB 86), P. aeruginosa (NCIB 950), and K. pneumoniae (NCIB 418). Moreover, the inhibitory concentrations of compound 9 were lower than those of streptomycin, underscoring its efficacy as a potential antibacterial agent. These findings suggest that the synthesized hydrazone derivatives possess significant potential as novel and effective antibacterial agents, warranting further exploration in the field of antibacterial drug development.

Production of kojic acid by Aspergillus flavus OL314748 using box-Behnken statistical design and its antibacterial and anticancer applications using molecular docking technique

Kojic acid is a wonderful fungal secondary metabolite that has several applications in the food, medical, and agriculture sectors. Many human diseases become resistant to normal antibiotics and normal treatments. We need to search for alternative treatment sources and understand their mode of action. Aspergillus flavus ASU45 (OL314748) was isolated from the caraway rhizosphere as a non-aflatoxin producer and identified genetically using 18S rRNA gene sequencing. After applying the Box-Behnken statistical design to maximize KA production, the production raised from 39.96 to 81.59 g/l utilizing (g/l) glucose 150, yeast extract 5, KH2PO4 1, MgSO4.7H2O 2, and medium pH 3 with a coefficient (R2) of 98.45%. Extracted KA was characterized using FTIR, XRD, and a scanning electron microscope. Crystalized KA was an effective antibacterial agent against six human pathogenic bacteria (Bacillus cereus, Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, Serratia marcescens, and Serratia plymuthica). KA achieves high inhibition activity against Bacillus cereus, K. pneumonia, and S. plymuthica at 100 μg/ml concentration by 2.75, 2.85, and 2.85 compared with chloramphenicol which gives inhibition zones 1, 1.1, and 1.6, respectively. Crystalized KA had anticancer activity versus three types of cancer cell lines (Mcf-7, HepG2, and Huh7) and demonstrated high cytotoxic capabilities on HepG-2 cells that propose strong antitumor potent of KA versus hepatocellular carcinoma. The antibacterial and anticancer modes of action were illustrated using the molecular docking technique. Crystalized kojic acid from a biological source represented a promising microbial metabolite that could be utilized as an alternative antibacterial and anticancer agent effectively.

Essential Oils from the Perspective of Dentistry

Introduction: With a significant increase in interest in recent years regarding essential oils, the purpose of this work was to identify how Dentistry has researched and utilized these substances through an integrative review of articles available in indexed databases. The bibliographic survey was conducted in November and December 2022, through electronic research, consulting the Pubmed and LILACS databases. The descriptors and boolean operators used were: "volatile oils" OR "essential oils" AND "dentistry". The material published between 2018 and 2022 indexed in the mentioned databases and with a free version was included. Studies that did not address the proposed study theme were excluded. Material and Method: Out of 104 scientific articles found, 29 studies were reviewed and analyzed. Result and Discussion: A variety of plant derivatives have been studied for their inhibitory effect on C. albicans biofilms and for cytotoxicity, several are considered promising for the development of future research and bioproducts applicable to human health. Clinical studies indicated that the EOs from Pelargonium graveolens and Zataria multiflora are potentially effective in treating oral candidiasis, and the most promising EOs were obtained from Allium tubeorosum, Cinnamomum cassia, Cinnamomum zeylanicum, and Coriandrum sativum L. Further non-clinical and clinical studies with these EOs are necessary to determine their potential use and safety for the treatment of oral candidiasis. Listerine mouthwash was often compared with other chemical agents, mainly chlorhexidine, which in terms of plaque control is considered the gold standard in efficacy and substantivity. However, the use of chlorhexidine has disadvantages like altered taste sensations, teeth discoloration. With all this, the World Health Organization (WHO) recommended that researchers analyze the use of natural products, such as extracts of herbs and plants, to combat these negative effects. In another randomized study, they concluded that the mouthwash containing aqueous extracts of essential oils was as effective antibacterial agents as chlorhexidine mouthwashes, corroborating with other descriptive and experimental studies. Conclusion: The articles demonstrated extensive study regarding essential oils in Dentistry, presenting various applications that are still being explored: they have potential in the development of preventive or therapeutic agents for various oral diseases, use in dental materials, and popular applications. There is still a need for more clinical trials to establish safety and efficacy in oral health due to the wide variety of existing essential oils.

Production, Quality Test, and Activity Evaluation of Methanol Extract and Nanoparticles from Pluchea indica (L.) Leaves as Additives in Natural Soap against Propionibacterium acnes

Pluchea indica (L.) leaves, both in the form of extracts and silver nanoparticles, are known to exhibit antibacterial activity, but they have not been widely utilized in the health sector, especially in dermatology. This study aims to determine the quality test and antibacterial evaluation of natural soap formulated with methanol extract and nanoparticles of Pluchea indica (L.) leaves against Propionibacterium acnes. The synthesis of silver nanoparticles (AgNPs) was conducted using the reduction method, with AgNO3 as a precursor and methanol extract of Pluchea indica (L.) leaves serving as a reducing agent or bioreductor. Natural soap was produced through the cold process method, with a curing period of 3 to 4 weeks. Natural soap, derived from herbal ingredients, was made by combining NaOH, essential oils, and additives such as methanol extract and silver nanoparticles from Pluchea indica (L.) leaves. Quality tests were performed to assess moisture content (MC), fatty acid content, and pH levels. Antibacterial activity was assessed utilizing the well-diffusion method, with various sample concentrations ranging from 1.0 g/mL to 0.0625 g/mL. The quality test results for all soap samples met the Indonesian National Standard (SNI) requirements for acidity, free fatty acids, and moisture content. The bar soap without additives exhibited antibacterial activity, with a maximum inhibition zone of 14.26 mm (at 0.25 g/mL) after 15 hours. Natural soap with methanol extract of Pluchea indica (L.) leaf demonstrated an inhibition zone of 11.49 mm (at 0.0625 g/mL) after 15 hours, while nanoparticle soap exhibited an inhibition zone of 12.77 mm (at 0.25 g/mL) after 12 hours. In summary, all soap samples showed antibacterial activity, indicating the potential of Pluchea indica (L.) leaves as effective antibacterial agents.

A new Eosin Y-based ‘turn[sbnd]on’ fluorescent sensor for ratiometric sensing of toxic mercury ion (Hg2+) offering unaided eye detection and its antibacterial activity

A unique fluorescent molecule (ND-S) was obtained from Eosin Y in two simple yet high yielding steps (1). ND-S has special metal ion sensing ability, such that it can selectively detect toxic Hg2+ present in very low concentration in aqueous solutions in the presence of other competing metal ions. The host-guest complexation is ratiometric and is associated with significant increase in fluorescence during the process. Isothermal titration calorimetry (ITC) experiments provided thermodynamic parameters related to interaction between ND-S and Hg2+. Using inductively coupled plasma mass spectrometry (ICP-MS), the Hg2+(aq) removal efficiency of ND-S was estimated to be 99.88%. Appreciable limit of detection (LOD = 7.4 nM) was observed. Other competing ions did not interfere with the sensing of Hg2+ by ND-S. The effects of external stimuli (temperature and pH) were studied. Besides, the complex (ND-M), formed by 1:1 coordination of ND-S and Hg2+ was found to be effective against the survival of Gram-positive bacteria (S. aureus and B. subtilis) with a high selectivity index. Moreover, bacterial cell death mechanism was studied systematically. Overall, we have shown the transformation of a toxic species (Hg2+), extracted from polluted water by a biocompatible sensor (ND-S), into an effective and potent antibacterial agent (ND-M).

Cytoplasmic Leakage and Protein Leakage Analysis of Ocimum Gratissimum Stem Extract-Mediated Silver Nanoparticles Against Wound Pathogens

ABSTRACT Aim: The current work intends to examine the antibacterial activity of silver nanoparticles (AgNPs) mediated by Ocimum gratissimum stem extract against wound infections. Materials and Methods: To evaluate the membrane damage brought on by AgNPs, analyses of cytoplasmic leakage and protein leakage assays were performed. Results: The outcomes demonstrated that all of the tested bacterial strains were significantly resistant to the AgNPs’ antibacterial activity. AgNPs damaged membranes and caused cellular contents to leak in the target pathogens, according to an examination of protein and cytoplasmic leakage. Conclusion: According to the current investigation, AgNPs mediated by Ocimum gratissimum stem extract may be effective antibacterial agents against microorganisms that cause wounds.

Construction of cationic conjugated microporous polymers containing pyrene units through post-cationic modification for enhanced antibacterial performance

BackgroundThe development of effective antibacterial agents with minimal cytotoxicity to human cells is a subject of great interest. Conjugated microporous polymers (CMPs) are a rapidly expanding and significant class of porous organic polymers. They are distinguished by their robust microporous architecture and π-conjugated framework. The molecular-level control over the pore structure and chemical composition of CMPs allows for precise customization to fulfill particular requirements. MethodsWe synthesized a cationic conjugated microporous polymer named Pyr-T-DPM Me CMP. This was achieved through post-synthetic modification of a pyrene-T-linked conjugated microporous polymer, Pyr-T-DPM CMP, formed via the Sonogashira coupling reaction of ethynyl pyrene (Pyr-T) and 2,5-dibromopyrimidine (Pyrimidine-Br2). The comprehensive analysis involved various techniques, including Fourier transform infrared (FTIR) spectroscopy, N2 adsorption/desorption isotherm, 13C solid-state NMR, X-ray photoelectron spectroscopy (XPS), thermogravimetry, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Significant findingsThe antimicrobial efficacy of the newly synthesized CMPs was tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. Due to the formation of N-methylpyrimidinium salts after quaternization, the cationic Pyr-T-DPM Me CMP exhibited enhanced bactericidal effectiveness against S. aureus compared to Pyr-T-DPM CMP, which lacked a positive charge. The viability of bacteria decreased with increasing concentrations of Pyr-T-DPM Me CMP, reaching maximum antimicrobial effectiveness at a concentration of 5 mg mL−1. To assess their impact on cell compatibility, we evaluated the cytotoxic effects on L929 cell fibroblasts, revealing minimal cytotoxicity towards L929 cells. Inspired by the superior antibacterial characteristics and exceptionally low toxicity of Pyr-T-DPM Me CMP, the novel cationic CMP developed in this study holds potential for application as beneficial antibacterial agent in the fields of environmental engineering and healthcare.

Novel half-sandwich ruthenium(II) nicotinic hydrazone complexes: An efficient class of catalyst for the N-alkylation of amines with benzyl alcohol via transfer hydrogen mechanism and effective antibacterial agents

A new series of half sandwich ruthenium(II) complexes supported by nicotinic acid hydrazone derivatives of general formula [Ru(ɳ6-p-cymene)(Cl)(L)], where L represents N’-benzylidenenicotinohydrazide (HL1), N’-(naphthalen-1-ylmethylene)nicotinohydrazide (HL2) or N’-(pyren-1-ylmethylene)nicotinohydrazide (HL3) were synthesized and fully characterized. The solid-state molecular structures of ligands and complexes were elucidated with single-crystal X-ray diffraction. The ligands HL1 and HL2 possess monoclinic crystal system with P21/c and C2/c space groups respectively, whereas all the three Ru(II) complexes C1–3 are typical three-legged piano-stool geometries with orthorhombic(Aba2) (C1) and triclinic(P-1) (C2–3) systems respectively. The catalytic activities of these ruthenium complexes in the synthesis of N-alkylated amines were explored. Under optimal reaction condition, the complex C3 was found to be the most efficient catalyst for the N-alkylation of primary to secondary amines using benzyl alcohol. A wide range of substrates have been studied that includes anilines bearing electron withdrawing/electron donating group, fused aromatic, heteroaromatic, alicyclic and aliphatic amines with good to excellent yield. In addition, the antibacterial activity of the complexes were tested against different human pathogenic bacteria, among them C2 complex with naphthyl moiety was found to be the most active one against both Gram-positive (S. aureus and E. faecalis) and Gram-negative (E. coli and K. pneumoniae) bacteria. These two different studies demonstrate the catalytic and biological importance of our newly prepared Ruthenium complex.

Synthesis of inorganic/organic hybrid-shell antibacterial polyurea microcapsules loaded with Ag/TiO2 nanoparticles

Silver/titanium dioxide (Ag/TiO2) nanoparticles, renowned as effective inorganic antibacterial agents with a wide spectrum of activity and minimal resistance induction, encounter challenges when incorporated into organic substrates. This integration often leads to particle aggregation, resulting in a substantial reduction in antibacterial efficacy. This study devised a novel approach involving loading Ag/TiO2 nanoparticles onto polyurea microcapsules (PUMC), forming hybrid-shelled microcapsules (Ag/TiO2-PUMC) using silane coupling agents. The preparation of polyurea microcapsules offers the advantages of rapid synthesis and mild reaction conditions, facilitating industrial-scale production. Additionally, loading Ag/TiO2 nanoparticles onto polyurea microcapsules helps alleviate the aggregation issue, and the organic nature of polyurea microcapsules enhances compatibility with organic substrates. Characterization techniques, including SEM, TEM, FTIR, XRD, UV–visible absorption spectroscopy, EPR and thermogravimetric analysis, were employed to confirm the successful grafting of Ag/TiO2 nanoparticles onto the PUMC. A comparative analysis between the two silane coupling agents, KH550 and KH792, revealed that the dual amino-functional silane coupling agent, KH792, played a pivotal role in chain extension during the microcapsule self-polymerization process. The antibacterial activity of the Ag/TiO2-PUMC was evaluated against Escherichia coli and Staphylococcus aureus. Remarkably, the hybrid-shelled microcapsules exhibited outstanding antibacterial efficacy, achieving a 99.99% antibacterial rate within just 0.5 hours. This performance surpassed unmodified Ag/TiO2 nanoparticles, highlighting the enhanced antibacterial efficacy of the hybrid-shelled microcapsule structure. This study presents a successful synthesis strategy for inorganic/organic hybrid-shelled antibacterial microcapsules and provides valuable insights for refining inorganic antibacterial agents. The demonstrated approach holds substantial promise for advancing the field of organic antibacterial materials.

Alkaline protease based hydrothermal synthesis of novel Pd/CuO/ZnO nanocomposite: A new entry into photocatalytic and biomedical applications

Here, we reported the process for the production of Pd/CuO/ZnO nanocomposite utilizing alkaline protease from Phalaris minor seed extract, which is a unique, effective biogenic approach. Alkaline protease performed a crucial part in the reduction, capping and stabilization of Pd/CuO/ZnO nanocomposites. A series of physicochemical techniques were used to inquire the formation, size, shape and crystalline nature of Pd/CuO/ZnO nanocomposites. The notable performance of the synthesized nanocomposite as a photocatalyst and an antibacterial disinfectant was astonishing. The Pd/CuO/ZnO nanocrystals showed considerable photocatalytic activity by eliminating 99 % of the methylene blue (MB) in <30 min of exposure. After three test cycles, the nanocatalyst demonstrated exceptional reliability as a photocatalyst. The nanocomposite was also discovered to be an effective antibacterial agent, with zones of inhibitory activity for Staphylococcus aureus and Escherichia coli bacteria of 30(±0.2), 27(±0.3), 22(±0.2), and 21(±0.3) mm, respectively, in both light and dark conditions. Moreover, the Pd/CuO/ZnO nanocomposites showed strong antioxidant activity by efficiently scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. The photocatalytic, antibacterial and antioxidative performance of Pd, CuO, ZnO, and CuO/ZnO were also assessed for the sake of comparison. This work shows that biogenic nanocomposites may be employed as a feasible alternative photocatalyst for the decomposition of dyes in waste water as well as a sustainable antibacterial agent.

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.

Studying the mechanism of action of new derivatives of quinoxalin-1,4-dioxide on the model organism Mycobacterium smegmatis

According to the World Health Organization (WHO), antibiotic resistance is currently one of the most serious threats to human health, food security, and development. Tuberculosis (TB) remains one of the deadliest bacterial diseases. The primary challenge in treating tuberculosis infection is the emergence of strains with multidrug resistance (MDR) to 4-9 drugs. The emergence of bacterial strains with MDR is a consequence of patients’ insufficient adherence to treatment, interrupted therapy, improperly prescribed courses of chemotherapy, and, according to recent data, the accumulation of antibiotics in the environment, which can activate the natural drug resistance system in bacteria. The consequences of MDR to antibiotics include prolonged hospitalizations, increased medical expenses, and mortality. Therefore, the task is to develop new effective antibacterial agents with novel mechanisms to reduce the emergence of bacterial resistance. In this study, we investigated the mechanisms of action of new promising antimycobacterial derivatives of quinoxalin-1,4-dioxide on the model organism Mycobacterium smegmatis .

Self-reinforced multifunctional starch nanocomposite film for litchi fruit postharvest preservation

Consumers enjoy fruit because of its delicious flavor and nutritional value. However, fruit is also prone to oxidation and microbial infection after picking. Therefore, it is imperative to produce safe antiseptic packing materials. Starch films have received considerable attention as an alternative to conventional plastics. The addition of other antibacterial active materials to starch film can significantly improve performance, including water resistance, anti-oxidation, and antibacterial properties. Selenium nanoparticles (SeNPs) have exceptional anti-oxidation and antibacterial characteristics and are therefore considered effective antibacterial agents. In this study, we utilized polyphenol and polysaccharide interactions to improve the structure-biological activity of SeNPs to introduce anti-oxidation, antibacterial properties, and UV-blocking performance to extend the shelf life of food and achieve self-reinforcement, thus improving the mechanical properties of the material and making it suitable for food packaging. Notably, the process for the preparation of the SeNPs-embedded starch film was environmentally friendly (water as the solvent) and simple, with mild reaction conditions. The results from this study demonstrated the ability of starch film to reduce dehydration, prevent nutrient loss, inhibit microbe growth, preserve litchi quality, and extend the shelf life during storage. In addition, the film demonstrated biodegradability (11 days in soil), good biocompatibility, and biosafety, offering significant potential for the development of safe and sustainable food packaging systems. This phytochemical nano-enhancement starch film offers a promising solution for multipurpose active food packaging.

Genome mining of Bacillus licheniformis MCC2514 for the identification of lasso peptide biosynthetic gene cluster and its characterization.

The probiotic strain Bacillus licheniformis MCC2514 has been shown to produce a strong antibacterial peptide and the whole genome sequence of this strain is also reported in our previous study. The present study is focused on the genome level investigation of this peptide antibiotic and its characterization. Genome mining of the culture revealed the presence of three putative bacteriocin clusters, viz. lichenicidin, sonorensin and lasso peptide. Hence, the mode of action of the peptide was investigated by reporter assay, scanning electron microscopy, and Fourier Transform Infrared spectroscopy. Additionally, the peptide treated groups of Kocuria rhizophila showed a reduction in the fold expression for transcription-related genes. The gene expression studies, quantitative β-galactosidase induction assay using the RNA stress reporter strain, yvgS along with the homology studies concluded that lasso peptide is responsible for the antibacterial activity of the peptide which acts as an inhibitor of RNA biosynthesis. Gene expression analysis showed a considerable increase in fold expression of lasso peptide genes at various fermentation hours. Also, the peptide was isolated, and its time-kill kinetics and minimum inhibitory concentration against the indicator pathogen K. rhizophila were examined. The peptide was also purified and the molecular weight was determined to be ~ 2kDa. Our study suggests that this bacteriocin can function as an effective antibacterial agent in food products as well as in therapeutics as it contains lasso peptide, which inhibits the RNA biosynthesis.

Solar-activated and hydrothermally synthesized effective rGO/Ag2S composites for the destruction of naphthol green B dye and antibacterial applications.

Graphene-based nanocomposites are developing as a new class of materials with several uses. The varied weight percentages of rGO on Ag2S catalysts were synthesized using a simple hydrothermal process and employed for the decomposition of anionic dye naphthol green B (NGB) under solar light. The reduced graphene oxide-based silver sulfide (rGO/Ag2S) nanoparticles were then examined using XRD, SEM, EDS, HR-TEM, XPS, UV-DRS, and PL analysis. Using solar light, the photocatalytic activity of the produced catalyst was examined for the degradation of naphthol green B (NGB) in an aqueous solution. At pH 9, rGO/Ag2S is discovered to be more effective than the other catalysts for the NGB dye mineralization. Analyses have been conducted on the influence of operational parameters on the photo-mineralization of NGB, including the initial pH, initial dye concentration, and catalyst dosage. The dye concentration increased; the efficiency of photocatalytic degradation tended to decrease. Chemical oxygen demand (COD)studies have verified the NGB dye mineralization. Active species trapping revealed that holes, hydroxyl radicals, and superoxide radicals all played major roles in the photocatalytic deterioration of NGB processes. Additionally, a potential mechanism of NGB dye degradation by rGO/Ag2S catalyst is presented. The synthesized compound was further evaluated for antibacterial activity, and the results indicated that rGO/Ag2S were potentially effective antibacterial agents.