Antibacterial Research Articles

Gold Nanoparticles: Multifunctional Properties, Synthesis, and Future Prospects

Gold nanoparticles (NPs) are among the most commonly employed metal NPs in biological applications, with distinctive physicochemical features. Their extraordinary optical properties, stemming from strong localized surface plasmon resonance (LSPR), contribute to the development of novel approaches in the areas of bioimaging, biosensing, and cancer research, especially for photothermal and photodynamic therapy. The ease of functionalization with various ligands provides a novel approach to the precise delivery of these molecules to targeted areas. Gold NPs’ ability to transfer heat and electricity positions them as valuable materials for advancing thermal management and electronic systems. Moreover, their inherent characteristics, such as inertness, give rise to the synthesis of novel antibacterial and antioxidant agents as they provide a biocompatible and low-toxicity approach. Chemical and physical synthesis methods are utilized to produce gold NPs. The pursuit of more ecologically sustainable and economically viable large-scale technologies, such as environmentally benign biological processes referred to as green/biological synthesis, has garnered increasing interest among global researchers. Green synthesis methods are more favorable than other synthesis techniques as they minimize the necessity for hazardous chemicals in the reduction process due to their simplicity, cost-effectiveness, energy efficiency, and biocompatibility. This article discusses the importance of gold NPs, their optical, conductivity, antibacterial, antioxidant, and anticancer properties, synthesis methods, contemporary uses, and biosafety, emphasizing the need to understand toxicology principles and green commercialization strategies.

Solubility of Sulfamerazine in Acetonitrile + Ethanol Cosolvent Mixtures: Thermodynamics and Modeling

Sulfamerazine (SMR) is a drug used as an antibacterial agent in the treatment of some pathologies, such as bronchitis, prostatitis and urinary tract infections. Although this drug was developed in 1945 and, due to its toxicity, was partially displaced by penicillin, due to the current problem of bacterial resistance, compounds such as SMR have regained validity. In this context, the thermodynamic study of SMR in cosolvent mixtures of acetonitrile (MeCN) + ethanol (EtOH) at nine temperatures (278.15–318.15 K) is presented. The solubility of SMR was determined by UV–Vis spectrophotometry, following the guidelines of the shake-flask method. The solubility process was endothermic in all cases; thus, the minimum solubility was reached in pure EtOH at 278.15 K, and the maximum solubility was reached in pure MeCN at 318.15 K. Both the solution process and the mixing process were entropy-driven. On the other hand, the solubility data were modeled by using the van’t Hoff–Yalkowsky–Roseman model, obtaining an overall average relative deviation of 3.9%. In general terms, it can be concluded that the solution process of SMR in {MeCN (1) + EtOH (2)} mixtures is thermodependent, favored by the entropy of the solution and mixture; additionally, the van’t Hoff–Yalkowsky–Roseman model allows very good approximations to be obtained and is a simple model that starts from only four experimental data.

Development of Cyclometalated Iridium(III) Complexes of 2‐Phenylbenzimidazole and Bipyridine Ligands for Selective Elimination of Gram‐Positive Bacteria

Herein, we have reported a series of cationic aggregation‐induced emission (AIE) active iridium(III) complexes (Ir1‐Ir5) of the type [Ir(C^N)2(N^N)]Cl, wherein C^N is a cyclometalating 2‐phenylbenzimidazole ligand with varying alkyl chain lengths and N^N is a 2,2ˊ‐bipyridine ligand attached to bis‐polyethylene glycol chains, for the treatment of bacterial infections. The AIE phenomenon of the complexes leveraged for detecting bacteria by fluorescence microscopy imaging that displayed a strong red emission in Gram‐positive bacteria. The antibacterial activity of the complexes assessed against Gram‐positive methicillin‐sensitive S. aureus, methicillin‐resistant S. aureus, E.faecium and E.faecalis and Gram‐negative E. coli and P.aeruginosa bacteria of clinical interest. The complexes Ir2‐Ir4 exerted potent antibacterial activity towards Gram‐positive strains with low minimum inhibitory concentrations (MICs) values in the range of 1−9 μM, which is comparable to clinically approved antibiotic vancomycin. In contrast, these complexes were found to be inactive towards Gram‐negative bacterial strains (MICs > 100 µM). The mechanism of antibacterial activity of the complexes implies that ROS generation, membrane depolarization and rupture are responsible for bacterial cell death. Further, the complexes Ir1‐Ir3 were found to be low‐toxic against human red blood cells and human embryonic kidney (HEK293) cells, indicating their potential for use as antibacterial agents.

Quantitative cytotoxicity analysis of antibacterial Janus nanoparticles in immune and cancer cells

Background Nanoparticles (NPs) hold promise as alternatives to antibiotics in the fight against multi-drug-resistant bacteria. However, concerns about their cytotoxicity, particularly their effects on mammalian cells, must be thoroughly addressed to ensure therapeutic safety. Amphiphilic Janus NPs, which have segregated hydrophobic and polycationic ligands on two hemispheres, have previously been shown to exhibit potent antibacterial activity. Methods In this study, we evaluated the cytotoxicity of amphiphilic Janus NPs in immune and cancer cell lines. Cytotoxicity assays were performed to assess the effects of Janus NPs on cell viability and membrane integrity, with a particular focus on how internalization of the nanoparticles influenced cellular responses. Results The results revealed that both immune and cancer cells exhibited negligible cytotoxic effects when exposed to Janus NPs. However, phagocytic immune cells demonstrated greater susceptibility to membrane damage and viability loss, suggesting that internalization plays a significant role in nanoparticle-induced cytotoxicity. Conclusions Amphiphilic Janus NPs show great potential as highly effective antibacterial agents with minimal cytotoxicity. While immune cells may be more vulnerable to nanoparticle-induced damage due to their internalization capacity, these findings support the further investigation of Janus NPs for clinical applications.

A novel α-mangostin derivative synergistic to antibiotics against MRSA with unique mechanisms

ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) remains a leading cause of hospital-acquired infections, often linked to complicated treatments, increased mortality risk, and significant cost burdens. Several antibacterial agents have been developed to address MRSA resistance. In this study, potential agents to combat MRSA resistance were explored, with the antibacterial activity of synthesized α-mangostin (α-MG) derivatives being evaluated alongside investigations into their cellular mechanisms against MRSA2. α-MG-4, featuring an allyl group at C3 of the lead compound α-MG, restored the sensitivity of MRSA2 to penicillin, enrofloxacin, and gentamicin, while also demonstrating improved safety profiles. Although α-MG-4 alone was ineffective against MRSA2, it exhibited an optimal synergistic ratio in vitro when combined with these antibiotics. This significant synergistic antibacterial effect was further confirmed in vivo using a mouse skin abscess model. Additionally, the synergistic mechanisms revealed that α-MG-4 was associated with changes in membrane permeability and inhibition of the MepA and NorA genes, which encode the efflux pumps of MRSA2. α-MG-4 also inhibited PBP2a expression, potentially by occupying a crucial binding site in a dose-dependent manner. IMPORTANCE Methicillin-resistant Staphylococcus aureus (MRSA)’s resistance to multiple antibiotics poses significant health and safety concerns. A novel α-mangostin (α-MG) derivative, α-MG-4, was first identified as a xanthone-based PBP2a inhibitor that reverses MRSA2 resistance to penicillin. The synergistic antibacterial effects of α-MG-4 were linked to increased cell membrane permeability and the inhibition of genes involved in efflux pump function.

The Chemistry and Pharmacological Properties of the Constituents of Toussaintia Orientalis - An Endangered Treasure of Biomedical Agents.

Toussaintia orientalis Verdc. (Annonaceae) is a medicinal plant species endemic to Tanzania. It is classified under the International Union for Conservation of Nature (IUCN) as an extremely endangered species threatened with extinction. The review covers the phytochemistry of this plant species and the pharmacological properties of the compounds obtained therefrom. The chemistry of this plant species entails natural products with different structures including uncommon cinnamoyl tetraketide derivatives, aristolactam alkaloids, and flavonoids. The review identifies 27 compounds belonging to different subclasses of natural products obtained from this species for the past fourteen years (2010-2024). These compounds are discussed along with other 13 related natural products. T. orientalis derived compounds exhibit varied potential pharmacological applications as antibacterial, anticancer, anti-inflammatory, antiviral, and neuroprotective agents. Some of the reported compounds displayed pharmacological properties corroborating the use of this plant species in traditional medicine. This review provides baseline data as one comprehensive compilation that will ignite interest and guide future research and development of therapeutic agents inspired by the chemodiversity presented by this plant species while at the same time attracting the attention of plant conservationists to initiate efforts to conserve this highly endangered biomedical treasure.

Antibacterial double-layer calcium phosphate/chitosan composite coating on metal implants for tissue engineering

In this study, four different promising two-layer composite coatings on titanium substrates with antibacterial properties were investigated. Two different types of antibacterial agents were used to impart antibacterial properties to the coatings: antibiotic amikacin (in three different concentrations) and zinc. Chitosan, which also has antibacterial properties, was used as a carrier layer for amikacin on a calcium phosphate coating incorporating zinc. This combination should enable long-term antibacterial properties of a bone implant and thus prevent potential complications during wound healing due to bacterial contamination. To examine the physico-chemical properties of the samples, the elemental, chemical and phase compositions, the thickness and the wettability of the coatings were investigated. The release of amikacin from the chitosan coatings was investigated using high-performance liquid chromatography. Antibacterial activity of the prepared coatings was evaluated against five hospital bacteria strains (Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus faecalis, Klebsiella pneumoniae) and one strain from the microbial strain collection (methicillin-resistant Staphylococcus aureus, ATCC 43300). To investigate the cell toxicity of the composite coating, cell adhesion, proliferation and osteogenic differentiation were tested with mesenchymal stem cells. According to the results, the composite coatings with an amikacin concentration of 5.0 and 7.5 percent by weight have the best biological and antibacterial properties.

Effective correction of manifestations of vaginal microflora disorders

Pathological vaginal discharge is one of the main reasons for visiting gynecologists. Despite the abundance of drugs, not all are compliant and quickly effective for pronounced itching and swelling in the introitus area. One of the most common causes of pathological leukemia is vaginal infections, which are represented by three main clinical forms: bacterial vaginosis (BV) – up to 50% of all cases; vulvovaginal candidiasis (CVV) – 20–25% and trichomonas vaginitis (TV) – 15–20% of cases, respectively. In this regard, retrospective analysis shows that patients with BV, KV, TV most often actively turn to a gynecologist or venereologist However, the fact that the cause of pathological whites in more than 30% of cases can be a mixed infection creates problems in treatment with the use of monodrugs (many relapses up to 40% or more). Therefore, for their treatment, it is considered rational to use the concept of the etiotropic approach, based on the local effect of combined vaginal drugs. The role of a combined topical drug, including those with a rapid anesthetic effect, was evaluated. Neo-Penotran Forte L is a logical combination of antibacterial agents and a local anesthetic used to treat manifest forms of vaginal infections and provide rapid relief of intolerable symptoms.

Synthesis and biological evaluation of novel aminoguanidine derivatives as potential antibacterial agents

In an effort to identify novel antibacterial agents, we presented two series of aminoguanidine derivatives that were designed by incorporating 1,2,4-triazol moieties. All compounds exhibited strong in vitro antibacterial activity against a variety of testing strains. Compound 5f was identified as a potent antibacterial agent with a minimum inhibitory concentration (MIC) of 2–8 µg/mL against S. aureus, E. coli, S. epidermidis, B. subtilis, C. albicans, multi-drug resistant Staphylococcus aureus and multi-drug resistant Escherichia coli and low toxicity (Hela > 100 µM). Membrane permeability and transmission electron microscopy (TEM) image studies demonstrated that compound 5f permeabilized bacterial membranes, resulting in irregular cell morphology and the rapid death of bacteria. The results of the present study suggested that aminoguanidine derivatives with 1,2,4-triazol moieties were the intriguing scaffolds for the development of bactericidal agents.

Combating Fungal Infections and Resistance with a Dual-Mechanism Luminogen to Disrupt Membrane Integrity and Induce DNA Damage.

Antifungal drug resistance is a critical concern, demanding innovative therapeutic solutions. The dual-targeting mechanism of action (MoA), as an effective strategy to reduce drug resistance, has been validated in the design of antibacterial agents. However, the structural similarities between mammalian and fungal cells complicate the development of such a strategy for antifungal agents as the selectivity can be compromised. Herein, we introduce a dual-targeting strategy addressing fungal infections by selectively introducing DNA binding molecules into fungal nuclei. We incorporate rigid hydrophobic units into a DNA-binding domain to fabricate antifungal luminogens of TPY and TPZ, which exhibit enhanced membrane penetration and DNA-binding capabilities. These compounds exhibit dual-targeting MoA by depolarizing fungal membranes and inducing DNA damage, amplifying their potency against fungal pathogens with undetectable drug resistance. TPY and TPZ demonstrated robust antifungal activity in vitro and exhibited ideal therapeutic efficacy in a murine model of C. albicans-induced vaginitis. This multifaceted approach holds promise for overcoming drug resistance and advancing antifungal therapy.

A peptide targeting outer membrane protein A of Acinetobacter baumannii exhibits antibacterial activity by reducing bacterial pathogenicity.

The World Health Organization has classified multidrug-resistant (MDR) Acinetobacter baumannii as a significant threat to human health, necessitating the urgent discovery of new antibacterial drugs to combat bacterial resistance. Outer membrane protein A of A. baumannii (AbOmpA) is an outer membrane-anchored β-barrel-shaped pore protein that plays a critical role in bacterial adhesion, invasion, and biofilm formation. Therefore, AbOmpA is considered a key virulence factor of A. baumannii. Herein, we screened three phage display peptide libraries targeting AbOmpA and identified several peptides. Among them, P92 (amino acid sequence: QMGFMTSPKHSV) exhibited the highest binding affinity with AbOmpA, with a KD value of 7.84 nM. In vitro studies demonstrated that although P92 did not directly inhibit bacterial growth, it significantly reduced the invasion and adhesion capabilities of multiple clinical isolates of MDR A. baumannii and concentration-dependently inhibited biofilm formation by acting on OmpA. Furthermore, the polymerase chain reaction results confirmed a significant positive correlation between the antibacterial effect of P92 and OmpA expression levels. Encouragingly, P92 also displayed remarkable therapeutic efficacy against A. baumannii infection in various models, including an in vitro cell infection model, a mouse skin infection model, and a mouse sepsis model. These results highlight P92 as a novel and highly effective antimicrobial molecule specifically targeting the virulence factor AbOmpA.

A Comprehensive Review on the Total Synthesis of Antibacterial Furanomycin and Its Analogs

l-(+)-Furanomycin 1 is a miniature antibacterial natural product that contains an α-amino acid core. This non-proteinogenic α-amino acid was first isolated in 1967 by Katagiri and co-workers from the fermentation broth of Streptomyces threomyceticus L-803 (ATCC 15795). It is a substrate of isoleucyl aminoacyl-tRNA synthetase that replaces isoleucine in the protein translation process and exhibits antibacterial properties in vitro. It effectively acts as an antibacterial agent against M. tuberculosis, E. coli, B. subtilis, and some Shigella and Salmonella bacterial species at concentrations as low as the micromolar range. Consequently, synthetic chemists have garnered considerable interest from their specific structure–activity profile, distinctive chemical compositions, and distinct biological profile. This review comprehensively describes cutting-edge synthetic methodologies for synthesizing furanomycin and its analogs reported to date. Therefore, this review will offer an initial perspective on synthesizing furanomycin and its customized compounds.

Chromosome architecture as a determinant for biosynthetic diversity in Micromonospora.

Natural products - small molecules generated by organisms to facilitate ecological interactions - are of great importance to society and are used as antibacterial, antiviral, antifungal and anticancer drugs. However, the role and evolution of these molecules and the fitness benefits they provide to their hosts in their natural habitat remain an outstanding question. In bacteria, the genes that encode the biosynthetic proteins that generate these molecules are organised into discrete loci termed biosynthetic gene clusters (BGCs). In this work, we asked the following question: How are biosynthetic gene clusters organised at the chromosomal level? We sought to answer this using publicly available high-quality assemblies of Micromonospora, an actinomycete genus with members responsible for biosynthesizing notable natural products, such as gentamicin and calicheamicin. By orienting the Micromonospora chromosome around the origin of replication, we demonstrated that Micromonospora has a conserved origin-proximal region, which becomes progressively more disordered towards the antipodes of the origin. We then demonstrated through genome mining of these organisms that the conserved origin-proximal region and the origin-distal region of Micromonospora have distinct populations of BGCs and, in this regard, parallel the organization of Streptomyces, which possesses linear chromosomes. Specifically, the origin-proximal region contains highly syntenous, conserved BGCs predicted to biosynthesize terpenes and a type III polyketide synthase. In contrast, the ori-distal region contains a highly diverse population of BGCs, with many BGCs belonging to unique gene cluster families. These data highlight that genomic plasticity in Micromonospora is locus-specific, and highlight the importance of using high-quality genome assemblies for natural product discovery and guide future natural product discovery by highlighting that biosynthetic novelty may be enriched in specific chromosomal neighbourhoods.

Antimicrobial Prescribing Patterns in GP Practices in Northern Ireland

Introduction: Antimicrobial resistance (AMR) is a global health threat requiring immediate attention as it is set to cause ten million deaths worldwide by 2050, overtaking that of cancer. Continuation of overuse and/or misuse of these crucial medicines will prevent future generations from reaping the benefits, as the pandemic of AMR spirals out of control. Aims: The primary aim of this study was to investigate antimicrobial prescribing patterns in General Practices throughout Northern Ireland. A secondary aim was to analyse the impact of the COVID-19 pandemic on antimicrobial prescribing and consumption patterns in GP practices in Northern Ireland. Methods: A retrospective, cross-sectional quantitative study was designed to measure, analyse, and evaluate the antimicrobial prescribing patterns within GP practices in Northern Ireland, using open access Business Services Organisation (BSO) data. Results: A total of 3,168.78 kg of antibacterial drugs were prescribed in primary care throughout the duration of the study. Penicillins were the most prescribed class (59.79%), followed by tetracyclines (10.68%) and macrolides (9.53%). Access group antibiotics were the most frequently prescribed (79.35%), followed by Watch group antibiotics (20.64%), with Reserve group antibiotics equating to nearly 0% despite being prescribed. The Derry GP Federation prescribed and dispensed the greatest amount of antibiotics overall in Northern Ireland (10.90%). Despite there being no significant difference in antibiotic prescribing amongst GP federations prior to and during the COVID-19 pandemic (unpaired t-test, p > 0.05), there were differences in prescribing of individual drug classes throughout this period. Conclusions: Despite meeting World Health Organisation (WHO) targets, GP practices within Northern Ireland must achieve more to further reduce antimicrobial consumption. Although antibiotic prescribing rates here are on the decline, there was no significant difference in prescribing amongst GP federations pre- and midst-COVID-19 pandemic, thus sufficient strategies such as increased communication between colleagues and supportive measures must be implemented within GP practices to enhance antimicrobial stewardship (AMS) across Northern Ireland.

Phytochemical Profiling and Anti-VanA Activity of Pulegone Extracted from Ziziphora tenuior Flower Against Vancomycin-Resistant Enterococci: an In Silico Approach.

Ziziphora tenuior is a herb known for its potent pharmaceutical activities. However, the specific compounds of the flowers of this herb have not been fully studied yet. This study used GC-MS to conduct a chemical analysis of the methanol and dichloromethane extracts of Z. tenuior flowers. Additionally, it sought to assess the potential antibacterial activity of the extracts against vancomycin-resistant enterococci (VRE) bacteria by predicting the interactions between one of the most prevalent compounds in the extracts and the D-alanyl-D-lactate ligase (VanA) protein, which is responsible for enterococci resistant to vancomycin. The results revealed a total of 15 compounds in the methanolic extract and 12 compounds in the dichloromethane extract. Among these, 5-methyl-2-(1-methylethylidene)-cyclohexanone, also known as pulegone, constituting 52.6 % of the methanolic extract and 34.6 % of the dichloromethane extract, was the most abundant compound in the extracts. Furthermore, the in-silico analysis demonstrated that pulegone exhibited significant interactions with VanA, as indicated by docking energy values of -7 kcal/mol and the formation of one hydrogen bond. The study suggests that pulegone shows promise as an antibacterial agent against VRE by potentially interacting with VanA protein and serving as a key inhibitor in fighting vancomycin resistance.

Sarecycline for moderate to severe acne: a promising narrow-spectrum antibacterial drug.

Sarecycline, a narrow-spectrum antibacterial drug approved by the FDA in 2018, targets Cutibacterium acnes while potentially minimizing disruption to the gut microbiota. The aim of this study is to assess the efficacy and safety of sarecycline compared to placebo in treating moderate to severe facial acne. A comprehensive search of PubMed, MEDLINE, and Cochrane databases was performed, with data extraction and screening conducted independently by two authors. Statistical analysis used RevMan, and the risk of bias was evaluated using RoB 2. Three RCTs (n = 2287 patients, mean age 19.6-20.8years) met the inclusion criteria. Sarecycline (1.5mg/kg) administered daily for 12weeks significantly reduced inflammatory and non-inflammatory lesion counts compared to placebo (p < 0.00001). Other outcomes were not statistically significant. Sarecycline 1.5mg/kg daily is an effective and well-tolerated treatment for moderate to severe acne with minimal side effects.

Control of Staphylococcus aureus infection by biosurfactant derived from Bacillus rugosus HH2: Strain isolation, structural characterization, and mechanistic insights

Novel antimicrobials are urgently needed to combat methicillin-resistant Staphylococcus aureus (MRSA) infections. This study explores the potential of biosurfactants derived from Bacillus rugosus HH2 as a novel antibacterial agent against MRSA. The biosurfactant, identified as surfactin, demonstrated surface-active properties, reducing surface tension to 37.63 mN/m and lowering contact angles in a concentration-dependent manner. It remained stable across a wide range of pH (4−10), temperatures (30–80 °C), and salinity levels (3–18 %). The biosurfactant inhibited the growth of both methicillin-sensitive S. aureus and MRSA, with minimum inhibitory concentrations ranging from 128 to 256 μg/mL. Additionally, it showed anti-biofilm activity, preventing biofilm formation and dispersing established biofilms. Field-emission scanning electron microscopy revealed that the biosurfactant disrupted bacterial cell membranes, leading to leakage. Furthermore, it reduced the production of virulence factors in S. aureus, including hemolysin and lipase. Transcriptomic analysis indicated downregulation of genes associated with quorum sensing and cell adhesion in MRSA. Molecular docking studies showed strong interactions between surfactin and key MRSA proteins, underscoring its potential to overcome antibiotic resistance. Biocompatibility was confirmed through in vitro cytotoxicity and in vivo phytotoxicity tests. In summary, this study presents surfactin as a promising novel antibacterial agent against MRSA, providing insights into its mechanisms of action.

Spectroscopic and chemical characterization of the novel Minocycline/Mn complex with evaluation of its invitro potent antioxidant activity and high antibacterial effect against Escherichia coli (ATCC 8739), Bacillus subtilis (ATCC6633), Staphylococcus aureus (ATCC 6538), and Klebsiella pneumonia (ATCC 13883)

Background and objectiveMinocycline (Mino) is a broad-spectrum antimicrobial that is quickly and fully absorbed. Mino is considered a unique tetracycline derivative. Recently, the number of commercially available antibacterial agents has declined, failing to keep pace with the number of challenges of treating pathogens resistant to multiple drugs. Therefore, it is necessary to develop new classes of antibiotics with different modes of action. Material and methodsThe Mino/manganese (Mino/Mn) complex was synthesized and characterized using elemental analysis, spectroscopic methods (infrared (IR), ultraviolet (UV), X-ray diffraction (XRD)), magnetic susceptibility, scanning electron microscopy SEM, and transmission electron microscopy (TEM). The non-electrolytic nature of the Mino/Mnnovel complex was confirmed based on the molar conductance value. The novel Mino/Mn complex was tested using the ORAC assay and evaluated for its antibacterial activity against the following strains: Escherichia coli (ATCC 8739), Bacillus subtilis (ATCC 6633), Staphylococcus aureus (ATCC 6538), and Klebsiella pneumonia (ATCC 13883). ResultsSpectral data showed that Mino is coordinated with Mn(II) through the oxygen atoms of ketonic (CO) and hydroxyl groups. The magnetic moment value confirms the octahedral configuration of the complex. Surface morphology observed via SEM confirmed that the Mino/Mn novel complex appeared as small rectangular projections. TEM showed the formation of black spots for Mn(II) chelate with particle sizes ranging from 9 to 23 nm. The current findings confirmed the high antibacterial activity of the Mino/Mn complex against the four mentioned strains of bacteria at extremely low concentrations: 0.625 mg/ml for E. coli, 0.009 for B. subtilis, and 0.625 for S. aureus. The Mino/Mn complex exhibited potent antioxidant activity by capturing and scavenging free radicals resulting from antibiotic misuse. ConclusionTherefore, it can be concluded that the novel formula of the Mino/Mn complex is an effective antioxidant and antibacterial agent with expected high potentially significant biological effects.

Synthesis of Mannich N-Bases Based on Benzimidazole Derivatives using SiO2-OAlCl2 Catalyst and Their Potential as Antioxidant, Antibacterial, and Anticancer Agents

This research aimed to synthesis of N-base compounds based on benzimidazole derivatives and their potential as antibacterials, antioxidants, and anticancer. The synthesis was conducted in two stages, namely the intermediate (benzimidazole derivatives) and the final product (N-mannich base), using five variations of organic acids and SiO2-OAlCl2 as catalyst. The results showed that the catalyst was successfully synthesized and characterized by The Fourier transform infrared (FTIR), X-ray diffraction (XRD), and Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS). The purity of the synthesized compounds was monitored by Thin layer chromatography (TLC), melting point test, Ultraviolet-visible (UV-Vis), FTIR, and Liquid chromatography-Mass spectrometry (LC-MS). The five intermediate compounds and five mannich base products yield 77%-89% and 65%-85%, respectively. The final products were applied through antibacterial testing against Staphylococcus aureus (Gram-positive bacteria) and Escherichia coli (Gram-negative bacteria) by disc diffusion. Mannich base compounds have potential antibacterial agents, but only 4A and 4E gave the best inhibition zone diameter. Meanwhile, the antioxidant testing result using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method showed the best activity in the mannich base compound 4E. The anticancer test result showed that the five mannich base compounds had potential as anticancer agents.

Polyphenolic Nano-formulations: A New Avenue against Bacterial Infection.

The gradual emergence of new bacterial strains impervious to one or more antibiotics necessitates discovering and applying natural alternatives. Among natural products, various polyphenols exhibit antibacterial activity. However, polyphenols with biocompatible and potent antibacterial characteristics are limited due to low aqueous solubility and bioavailability; therefore, recent studies are considering new polyphenol formulations. Nanoformulations of polyphenols, especially metal nanoparticles, are currently being investigated for their potential antibacterial activity. Nanonization of such products increases their solubility and helps attain a high surface-to-volume ratio and, therefore, a higher reactivity of the nanonized products with better remedial potential than nonnanonized products. Polyphenolic compounds with catechol and pyrogallol moieties efficiently bond with many metal ions, especially Au and Ag. These synergistic effects exhibit antibacterial pro-oxidant ROS generation, membrane damage, and biofilm eradication. This review discusses various nano-delivery systems for considering polyphenols as antibacterial agents.