Search Results (1,049)

Background/Objectives: The emergence of methicillin-resistant Staphylococcus aureus (MRSA) highlights the need for new antibacterial agents. Here, we report the identification and evaluation of a novel Gram-positive selective antibacterial: NDM-552. Methods: Antibacterial activity was determined by broth microdilution against a panel of Gram-positive and Gram-negative pathogens. Mechanistic studies included BOCILLIN-FL competition assays, microscale thermophoresis (MST), and antibiotic interaction with oxacillin and moenomycin. Additionally, time–kill analyses, frequency-of-resistance measurements, cytotoxicity assays, plasma stability studies, and a murine wound infection model were performed to characterize NDM-552. Results: NDM-552 exhibits activity against Gram-positive pathogens including S. aureus, Enterococcus faecium, and Staphylococcus epidermidis, with minimum inhibitory concentrations (MICs) of 1–2 µg/mL. NDM-552 displays no activity against Gram-negative bacteria. NDM-552 displays bacteriostatic activity against MRSA and additive interactions with oxacillin and moenomycin. The frequency of resistance in MRSA is low (2.39 × 10⁻⁹). BOCILLIN-FL competition assays and MST binding analysis identify the essential penicillin-binding protein 2 (PBP2) as the potential target of NDM-552. NDM-552 demonstrates acceptable cytotoxicity, favorable plasma stability, and reduces bacterial burden in a murine wound infection model. Conclusions: NDM-552 is a potent Gram-positive selective antibacterial agent that potentially targets PBP2-associated cell wall biosynthesis and exhibits in vivo efficacy against MRSA. Findings establish NDM-552 as a promising scaffold for the development of new antibacterial agents. Full article

Hemp (Cannabis sativa L.) inflorescences have been extensively characterized for their bioactive compounds, whereas less information is available on hemp leaves despite their potential as a source of nutrients and phytochemicals. This study compared leaves and inflorescences of four organically grown hemp cultivars (Finola, Futura 75, Dioica, and Kompolti) in terms of cannabinoid, terpene, and fatty acid profiles, lipid quality indices, and in vitro antibacterial activity. Antibacterial activity against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa was evaluated using MIC, MBC, and time–kill assays. Total cannabinoid content was approximately 2.7-fold higher in inflorescences than in leaves, which were also generally richer in terpenes. Leaves showed a more favorable fatty acid profile, with higher n-3 polyunsaturated fatty acid proportions and a lower n-6/n-3 ratio. All extracts exhibited antibacterial activity. Among the tested bacteria, S. aureus was the most susceptible to the hemp extracts, with both growth inhibition and bactericidal activity observed at the lowest tested concentration (MIC/MBC = 0.005%), compared with 0.625% for E. coli and 1.25–2.5% for P. aeruginosa, depending on the extract. Finola and Kompolti inflorescence extracts showed the fastest bactericidal activity against S. aureus. These findings demonstrate distinct and complementary characteristics of hemp leaves and inflorescences and provide a basis for further investigation of their potential relevance to canine nutrition. Full article

Background: Streptococcus suis serotype 2 is a major zoonotic pathogen responsible for severe systemic infections in pigs and humans, including septicemia, meningitis, and high mortality outcomes. Cefquinome, a fourth-generation β-lactam antibiotic widely used in veterinary medicine, is commonly applied for the treatment of S. suis infections. However, optimized dosing strategies remain insufficiently defined, particularly under conditions of varying bacterial burden, inoculum size, and reduced susceptibility or resistance phenotypes. These factors may significantly alter pharmacodynamic responses and compromise the predictive value of conventional MIC-based approaches. Objectives: This study aimed to characterize the pharmacokinetics (PK) and pharmacodynamics (PD) of cefquinome against S. suis serotype 2 using an integrated ex vivo serum time-kill experiments and semi-mechanistic PK/PD modeling. A secondary objective was to evaluate optimized dosing regimens across different inoculum levels and susceptibility phenotypes, including a cefquinome-resistant mutant. Methods: Cefquinome pharmacokinetics following intramuscular administration at 2 and 4 mg/kg in piglets were described using a two-compartment model. Dose proportionality, exposure linearity, and clearance parameters were assessed. Ex vivo serum time-kill experiments were conducted using a parental strain and a cefquinome-resistant mutant (M1) under normal-inoculum (NI), high-inoculum (HI), and mutant/resistant (MS) conditions. A semi-mechanistic PK/PD model incorporating logistic bacterial growth, sigmoidal Emax killing, nutrient limitation, and a time-delay function was developed to describe dynamic bacterial responses. Model parameters (k₀, k_max, EC₅₀) were estimated using nonlinear least-squares regression (Scientist v2.0), and simulations were performed by integrating time-varying PK input functions. Results: Cefquinome demonstrated linear pharmacokinetics with dose-proportional increases in Cmax and AUC between 2 and 4 mg/kg, with comparable clearance across doses. Ex vivo studies revealed time-dependent antibacterial activity with a pronounced inoculum effect. Higher bacterial burdens significantly reduced bactericidal efficiency and promoted regrowth during declining drug exposure. No tested concentrations achieved ≥3-log₁₀ killing in HI or MS conditions, whereas the NI group achieved a maximal reduction of 3.5-log₁₀ CFU/mL. MIC values in serum and medium were consistent (0.03, 0.06, and 0.24 µg/mL for NI, HI, and MS, respectively), indicating minimal protein binding influence. The semi-mechanistic model accurately described observed bacterial dynamics (R² > 0.99; MSC > 1.5), capturing delayed drug effects, inoculum-dependent growth suppression, and regrowth phenomena. Growth rates were reduced under serum conditions, reflecting nutrient limitation. Importantly, inoculum size exerted a stronger impact on pharmacodynamic outcomes than resistance phenotype, as reflected by reductions in kmax and increases in EC₅₀ under HI conditions. Although %T>MIC exceeded conventional β-lactam targets (>40%) in most regimens, MIC-based indices poorly correlated with observed dynamic killing responses. Conclusions: Cefquinome exhibited time-dependent antibacterial activity against S. suis serotype 2, strongly modulated by inoculum size and reduced susceptibility. The developed semi-mechanistic PK/PD model provided robust prediction of bacterial time-kill behavior and outperformed MIC-based metrics in guiding dose optimization. Simulation results support 2 mg/kg every 24 h for normal infections and 2 mg/kg every 12 h for high-inoculum or less susceptible infections, emphasizing the value of model-informed dosing strategies for optimizing β-lactam therapy. Full article

A hard protein corona was engineered onto tannic acid-modified magnetic nanoparticles (SAMN@TA), a magnetic and luminescent core–shell nano-carrier, using Bovine Serum Amine Oxidase (BSAO), an enzyme catalyzing the oxidation of polyamines and producing the corresponding aldehydes and hydrogen peroxide. The absorption and intracellular bioactivity of the self-assembled multimodal SAMN@TA@BSAO were investigated on an intestinal barrier model built with human colorectal adenocarcinoma (Caco-2) cells. The tailored BSAO corona possessed fouling resistance and, at the same time, was able to activate the clathrin-mediated endocytosis (CME) mechanism. Despite its size and intrinsic complexity, the nano-vehicle was effectively transported across the cell layer, safely transiting across the cell cytoplasm and reaching the lumen. As a function of intracellular polyamine concentration, the system’s biological activity induced intracellular oxidative stress, leading to the activation of the Keap1/Nrf2 oxidative protection pathway. The SAMN@TA@BSAO effect was well described by a dose–response curve with an EC50 of around 30 µg mL⁻¹ and a programmable killing efficiency (>50.0%), recalling the feasibility of a low molecular weight drug administration. The present study contributes to the nascent knowledge on engineering protein corona as a key to rationally design nanomaterials for biomedical applications. Full article

Background: Staphylococcus aureus (SA) causes septicemia and arthritis, eventually resulting in substantial economic losses and health hazards in poultry. Lethal electron beam (eBeam) treatment kills bacteria while preserving surface epitopes. Methods: This study compared broiler chicken immune responses (local and systemic) after eBeam-killed (eB) or formalin-killed (FK) SA injections. The vaccine (sham) control was endotoxin-free PBS. This study contained six treatments (trt) with five chickens/trt, with vaccine trts divided into two groups, A and B. Group A received in ovo vaccine/sham treatments (phase 1) initially. At 34 d of age, the pulps of growing feathers (GFs) received intradermal (i.d.) injections of the respective trt to elicit booster and primary responses in groups A and B, respectively. Blood was collected to analyze leukocyte populations and plasma SA-specific antibody levels. Additionally, in phase 2, GFs were collected to assess leukocyte presence in GF pulps. Two-way ANOVA was conducted to test the effects of treatment, time, and their interactions, followed by Tukey’s HSD tests at p < 0.05 for statistical significance. Results: Early in phase 1, the eB group had increased SA-specific IgM, IgA, and total lymphocyte concentrations compared with FK. In phase 2, FK and eB i.d. vaccines increased total lymphocyte and T cell proportions in GF pulps compared with sham. In blood, the recall eB vaccination increased monocytes, B cells, CD8+ T cells, and total lymphocytes, while the recall FK vaccination increased heterophils (p < 0.05). Conclusions: Improved early protection at mucosal surfaces may be reflected by higher plasma levels of SA-specific IgM and IgA following in ovo eBeam-killed-SA vaccination. Additionally, both eB-SA and FK-SA vaccines stimulated robust local inflammatory responses dominated by lymphocytes in GF pulps. Full article

Background: Antimicrobial resistance (AMR) is among the most pressing challenges in modern infectious medicine, driving progressive failure of standard antibacterial therapy and rising mortality from infections caused by multidrug-resistant (MDR) pathogens. Antibiotic potentiation through adjuvant compounds capable of restoring the activity of existing drugs represents a promising strategy to overcome resistance without developing fundamentally new antibacterial molecules. This study aimed to evaluate the antibiotic-potentiating activity of a dextrin/polyvinyl alcohol/iodine complex (D/PVA/I-1), developed at the Scientific Center for Anti-Infectious Drugs JSC (Almaty, Kazakhstan), against clinically relevant MDR reference strains. Methods: Nine reference strains, Staphylococcus aureus (ATCC 33591, BAA-39), Escherichia coli (ATCC BAA-196, BAA-2523), Klebsiella pneumoniae (ATCC BAA-2524, 700603), Acinetobacter baumannii (ATCC BAA-1790), Streptococcus pneumoniae (ATCC BAA-660), and Haemophilus influenzae (ATCC 33930), and two clinical isolates, P. aeruginosa SCAID PHRX1-2019 and E. coli SCAID WND1-2021, were tested. Antibiotic-potentiating activity was assessed by checkerboard assay with calculation of the fractional inhibitory concentration index (FICI); bactericidal kinetics were evaluated by time-kill analysis. The effect of D/PVA/I-1 on cytoplasmic membrane permeability was investigated using a crystal violet uptake assay. Results: Of 45 D/PVA/I-1–antibiotic combinations tested across nine antibiotics, synergy (FICI ≤ 0.5) was demonstrated in 44.4% of cases, partial synergy in 48.9%, and additive effects in 6.7%; no antagonistic interactions were detected. The most pronounced potentiating effect occurred against Gram-positive pathogens, particularly MRSA strains (66.7% synergistic combinations). Time-kill analysis confirmed suppression of the regrowth phenotype characteristic of MDR strains under monotherapy and restoration of bactericidal activity against antibiotics to which strains exhibited intrinsic resistance. D/PVA/I-1 induced a dose- and time-dependent increase in membrane permeability in both Gram-positive and Gram-negative organisms. Conclusions: D/PVA/I-1 is an effective broad-spectrum antibiotic potentiator and represents a promising basis for combination therapy regimens against MDR infections. Full article

Acinetobacter baumannii, particularly colistin-resistant strains, represents a major therapeutic challenge because of multidrug resistance, biofilm formation, and limited treatment options. This study investigated the antibacterial, antibiofilm, immunomodulatory, and therapeutic potential of Withania somnifera ethanolic root extracts (WSEEs) against drug-sensitive (DS) and colistin-resistant (CR) A. baumannii. WSEE exhibited concentration-dependent antibacterial activity, with MIC/MBC values of 125/250 μg/mL against the DS isolate and 250/500 μg/mL against the CR isolate. Time–kill analysis demonstrated bactericidal activity at 250 μg/mL, and WSEE significantly reduced the biomass of preformed biofilms. In cyclophosphamide-induced leukopenic mice, oral administration of WSEE (100 and 200 mg/kg) restored leukocyte counts and significantly reduced pulmonary bacterial burden following infection with both isolates. The higher dose (200 mg/kg) achieved survival rates of 90% and 70% in mice infected with the DS and CR isolates, respectively, compared with 50% and 30% in the corresponding colistin-treated groups. WSEE also significantly decreased serum levels of the pro-inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), indicating attenuation of infection-associated inflammation. Biochemical analyses further showed that WSEE did not produce detectable hepatotoxicity or nephrotoxicity under the experimental conditions. Collectively, these findings demonstrate that WSEE possesses antibacterial, antibiofilm, anti-inflammatory, and immunomodulatory activities and provides therapeutic benefit in experimental A. baumannii infection. These results support the potential of WSEE as a complementary therapeutic strategy against multidrug-resistant A. baumannii, while further mechanistic, pharmacokinetic, and translational studies are needed to validate its clinical potential. Full article

Background/objectives: Multidrug-resistant and extensively drug-resistant Gram-negative pathogens are a major cause of severe ocular infections, yet treatment options are increasingly compromised by escalating antibiotic resistance. Membrane-active peptides (colistin and Mel4) offer the potential to restore antibiotic susceptibility. This study investigated the efficacy of peptide- and colistin-based adjuvant strategies in enhancing the activity of conventional antibiotics. Methods: Antibacterial activity was assessed using MIC/MBC testing, checkerboard assays, time–kill kinetics, and biofilm disruption studies, supported by confocal microscopy. Toxicity was assessed using L929 fibroblasts and red blood cells. A mechanistic study was performed with a membrane permeability assay. Results: Clinical isolates of Pseudomonas aeruginosa, Acinetobacter baumannii, and Klebsiella pneumoniae showed high resistance to six antibiotic classes (up to MICs > 2048 mg/L), while polymyxin B and colistin remained active (MIC ≤ 2 mg/L). Mel4 displayed variable activity (MIC 7.8–500 mg/L). A total of 102 antibiotic–antibiotic, antibiotic–Mel4, and antibiotic–colistin combination tests were performed, of which 45 showed synergistic interactions. Combining traditional antimicrobials with either colistin or Mel4 restored antibiotic susceptibility, reducing MICs up to 2048-fold. Aminoglycoside–colistin combinations significantly lowered MICs, especially against K. pneumoniae. Time–kill assays confirmed rapid bactericidal effects (>3 log10 reduction in 3 h). The ciprofloxacin–Mel4 combination effectively disrupted biofilms (62–92%) with low toxicity and high cell viability. Membrane permeability assays showed that ciprofloxacin has limited activity, whereas both Mel4 and the ciprofloxacin–Mel4 combination showed enhanced activity across concentration gradients and over time. Conclusions: Membrane-active antimicrobials, colistin and Mel4, enhance conventional antibiotics against multidrug- and extensively drug-resistant ocular Gram-negative pathogens by restoring susceptibility, accelerating bactericidal effects, and disrupting biofilms. With low toxicity, these combinations represent promising therapeutic strategies for severe multidrug-resistant ocular infections. Full article

One respondent says antibiotics kill viruses. A second says they do not know. A third says cancer cures are hidden for profit. A standard literacy score counts all three as one deficit. This exploratory study asks whether they behave alike. In a July 2025 Romanian telephone survey (analytic N = 1007), six factual, two worldview-linked and two conspiratorial anti-science (CAS) items were analyzed separately, treating “don’t know” (DK) as a third response. The response patterns did not converge. Factor analysis of substantive answers retained two factors, not one, and the six-item core’s weighted internal consistency among answerers was 0.379. DK responding formed a coherent cross-item pattern, but less uniform than the full-sample alpha of 0.926 implies: it falls to 0.803 once the 135 all-DK respondents are set aside. CAS endorsement converged with generic conspiracist belief and tracked institutional distrust, where factual accuracy did not. Education and internet frequency mainly differentiated DK responding; economic security and democratic satisfaction were associated with lower CAS endorsement. Against Eurobarometer 95.2 (2021), Romanian factual accuracy sits about two items lower than the EU27 average excluding Romania, and CAS endorsement is roughly 1.7 times as high, in both Romanian waves. Uncertainty, error and conspiratorial belief remain conceptually distinct. Full article

Pine wilt disease, caused by Bursaphelenchus xylophilus and vectored by Monochamus alternatus, is a devastating forest disease. The parasitoid Sclerodermus guani and entomopathogenic fungus Beauveria bassiana are effective biocontrol agents against wood-boring pests, but their compatibility remains poorly understood. We exposed adult female S. guani to three concentrations of B. bassiana conidia (1 × 10⁵, 1 × 10⁶, and 1 × 10⁷ conidia mL⁻¹) and assessed parasitoid mortality, infection, reproduction, and parasitism capacity against M. alternatus larvae. Mortality and infection rates increased significantly with concentration and exposure time. At 30 days post-exposure, corrected mortalities were 72.47%, 91.30%, and 100% for the three concentrations, respectively. Time–dose–mortality analysis yielded LT₅₀ values of 27.69, 20.00, and 5.92 days, confirming faster kill at higher doses. Fungal exposure reduced offspring production and development at high concentrations, yet fungus-carrying females still successfully parasitized M. alternatus. Importantly, low fungal concentrations caused only minor reductions in parasitism success and offspring survival. These findings demonstrate that the compatibility between B. bassiana and S. guani is strongly concentration-dependent. Therefore, optimizing fungal dosage is essential to balance fungal dispersal and parasitoid fitness in fungus-carrying biocontrol systems. Our study provides valuable insights into ecological interactions between entomopathogenic fungi and parasitoids, facilitating integrated pest management strategies for wood-boring pests. Full article

Chemokines are best known for orchestrating leukocyte migration; however, accumulating evidence indicates that mammalian CXCL14 also functions as a direct antimicrobial effector of innate immunity. Nevertheless, the molecular basis underlying the bactericidal activity of fish chemokines remains largely unexplored. In this study, we identified and functionally characterized Ctenopharyngodon idella CXCL14 (CiCXCL14) as a broad-spectrum antimicrobial protein. CiCXCL14 is predominantly expressed in immune-related organs and is significantly upregulated upon Aeromonas hydrophila challenge, suggesting an active role in antibacterial defense. Recombinant CiCXCL14 exhibited potent, concentration-dependent bactericidal activity against E. coli, A. hydrophila, P. fluorescens, A. veronii, S. aureus, and S. agalactiae. Time-kill assays further demonstrated that CiCXCL14 exhibited rapid bactericidal activity, achieving near-complete killing of S. aureus within 40 min and E. coli within 160 min. Mechanistically, CiCXCL14 disrupts bacterial membrane integrity and interacts with purified bacterial genomic DNA, indicating that membrane damage and DNA interaction may both contribute to its bactericidal activity. Notably, CiCXCL14 retained substantial antibacterial activity after heat treatment, whereas its activity gradually decreased with increasing NaCl concentrations. In vivo, administration of recombinant CiCXCL14 improved survival rates in grass carp challenged with a lethal dose of A. hydrophila and reduced bacterial burdens in the liver, spleen, and trunk kidney. Collectively, these findings identify CiCXCL14 as a teleost chemokine with direct antibacterial activity and demonstrate that it contributes to antibacterial defense through membrane disruption and interaction with bacterial DNA. These findings provide a foundation for future studies investigating the potential application of CiCXCL14 in aquaculture disease control. Full article

The development of antimicrobial compounds using biocatalytic synthesis routes is of interest in sustainability-oriented chemical and food-related research. In this study, phloretic acid was enzymatically esterified with two naturally occurring terpenoid alcohols, geraniol and myrtenol, using Candida antarctica lipase B as a biocatalyst under mild conditions. The study combined terpenoid and phenolic molecular building blocks with a biocatalytic synthesis route and evaluated the resulting esters as preliminary in vitro antimicrobial candidates. The resulting esters were isolated in moderate yields, reaching 65.51% for geranyl 3-(4-hydroxyphenyl)propanoate and 54.50% for myrtenyl 3-(4-hydroxyphenyl)propanoate. Their antimicrobial activity, together with that of the parent compounds, was evaluated against a limited panel comprising two Gram-positive bacteria, two Gram-negative bacteria, and two yeast species, by determining the minimum inhibitory concentration (MIC) and minimum microbicidal concentration (MMC). The tested terpenoid alcohols showed notable antifungal activity, whereas esterification was associated with a marked increase in activity against the tested Staphylococcus aureus PCM 2054 strain. Both phloretic acid terpenyl esters showed the lowest measured MIC and MMC values against S. aureus, at 0.227 and 0.455 mM, respectively. These MIC values represented 16- and 64-fold decreases relative to the corresponding parent terpenoid alcohols and phloretic acid, respectively. Geranyl 3-(4-hydroxyphenyl)propanoate was selected for time-kill analysis because both esters showed the same measured MIC and MMC values against S. aureus PCM 2054, whereas the geranyl ester provided a higher isolated yield, more favorable calculated reaction-stage process descriptors, and a slightly lower geometric mean MIC across the tested microbial panel. In the time-kill experiment, G4HPP at 0.25 and 0.50 mM, corresponding to approximately 75.6 and 151.2 mg/L, respectively, produced an estimated 3-log reduction in viable S. aureus PCM 2054 counts after approximately 4.7 and 4.3 h. A small increase in viable counts was observed between 8 and 24 h. Supporting in silico analysis indicated that esterification increased predicted lipophilicity and decreased predicted aqueous solubility, accompanying the microorganism-dependent changes observed in the antimicrobial activity profile. Overall, the synthesized esters should be regarded as preliminary in vitro antimicrobial candidates displaying greater in vitro activity against the tested S. aureus PCM 2054 strain than the corresponding parent compounds. Broader strain-panel studies and evaluation in food-relevant matrices are required before any potential food-preservation application can be considered. Full article

To cope with severe seasonal changes in climate and food availability, colonies of Apis mellifera L. generate two distinct worker phenotypes during winter and summer. The aim of this research was to evaluate the effect of oral exposure to insecticides on the toxic susceptibility of winter and summer honeybee workers (Apis mellifera L.) under laboratory conditions. In this work, under all tested conditions and seasons, emamectin benzoate was the most toxic compound and used as the standard (Toxicity Index = 100) for comparison with other compounds. It had the lowest LC₅₀ (Lethal Concentration required to kill 50% of the tested honeybees) values, which decreased to 0.004 mg/L in winter bees after 48 h following oral exposure. Sulfoxaflor had moderate toxicity, and indoxacarb was the least toxic to honeybees. The results also revealed that the toxic effect was time-dependent, with lethal concentrations at 48 h significantly lower than those at 24 h. In addition, seasonal effects play a role; winter honeybees were, overall, more sensitive to the treatments than summer honeybees. Under the conditions of this study, it can be concluded that emamectin benzoate was the most toxic substance and indoxacarb the least toxic. Toxicity increased with exposure time. Winter honeybees showed greater sensitivity than summer honeybees. A field-relevant Hazard Quotient (HQ) analysis further indicated that indoxacarb, despite its lower acute toxicity, exhibited the narrowest margin relative to field-recommended spray concentrations, highlighting the value of incorporating field-relevant exposure metrics alongside LC₅₀-based rankings in pollinator risk assessment. It is worth clarifying that this narrower margin reflects indoxacarb’s higher field-recommended application rate relative to its LC₅₀, rather than a greater intrinsic toxicity than emamectin benzoate, and the two aspects of risk (intrinsic toxicity vs. use-rate-based field risk) should be interpreted separately. Full article

The Evil Twin attack, which involves creating rogue Wi-Fi access points that impersonate legitimate networks, remains one of the most persistent and adaptive threats in cybersecurity, despite more than two decades having passed since its first public demonstration in 2005. This paper aims to provide a comprehensive analysis of the evolution of this attack, perceived as an “invisible enemy” due to its low detectability and systematic underestimation in incident reports. The study addresses key questions: how the Evil Twin attack has evolved, how its methods and tools have changed, where it currently stands, and where it may be heading in the future. The paper compiles evidence from conference presentations, academic publications, government reports, industry analyses, and media coverage, as well as selected defense mechanisms such as WIPS, WPA3, Protected Management Frames, ETGuard, and the Trusted Wireless Environment framework. An original taxonomy of Evil Twin attack mutations is proposed, along with a ten-stage Kill Chain model ([A]–[J]) mapped onto the MITRE ATT&CK framework, an exposure time metric $T_e$ as a key evolutionary parameter, and models quantifying attack cost-effectiveness and efficiency. The analysis demonstrates that the Evil Twin remains a persistent and adaptive threat, whose effectiveness stems from the combination of technical vulnerabilities, user trust in familiar network names, and the difficulty of unambiguous attribution and classification of incidents. Full article

The escalating crisis of bacterial antimicrobial resistance necessitates the discovery of novel antibacterial agents with distinct mechanisms of action. Ursolic acid (UA), a naturally abundant pentacyclic triterpenoid, serves as a promising scaffold for structural modification. In this study, a series of 26 novel UA derivatives (A1–A7 and B1–B19) were designed and synthesized by introducing various substituents at the C-28 carboxyl group via a chloroacetyl chloride linker. Their antibacterial activities were evaluated against S. aureus, S. epidermidis, E. coli, and P. aeruginosa using the microbroth dilution method. Among them, compound B1 exhibited the most potent activity, with a minimum inhibitory concentration (MIC) of 37.5 μg/mL against S. aureus and 75 μg/mL against E. coli. Antibacterial kinetic and time-kill curve assays confirmed the sustained bactericidal effect of B1. Furthermore, B1 significantly inhibited biofilm formation in both S. aureus and E. coli in a time-dependent manner. Molecular docking studies revealed that B1 binds spontaneously to the S. aureus SarA protein through three hydrogen bonds and π-π stacking interactions, providing a structural basis for its antibacterial and anti-biofilm activities. This study demonstrates that piperazine-modified UA derivative B1 is a promising antibacterial candidate and offers a new strategy for the structural optimization of ursolic acid. Full article