Search Results (10,427)

Background/Objectives: Carbon dots (CDs) are promising antimicrobial nanomaterials owing to their biocompatibility, environmental friendliness, and tunable surface chemistry. This study aimed to synthesize nitrogen-doped CDs (AS-CDs) and develop a light-responsive antibacterial system through conjugation with chlorin e6 (Ce6). Methods: AS-CDs were synthesized by a microwave-assisted method using L-ascorbic acid and spermidine, followed by conjugation with Ce6. The materials were characterized by transmission electron microscopy, zeta potential analysis, and spectroscopic methods, and their antibacterial activity was evaluated against Escherichia coli, Staphylococcus aureus, and methicillin-resistant S. aureus (MRSA) under both dark and visible-light conditions. Cytotoxicity was assessed using HaCaT cells. Results: The AS-CDs exhibited a uniform nanoscale morphology with an average diameter of 6.3 nm and a positive surface charge of +15.6 mV, together with intrinsic broad-spectrum antibacterial activity. Ce6 conjugation further enhanced antibacterial efficacy under light irradiation, with the CDs-Ce6 conjugate achieving complete eradication of S. aureus and MRSA and marked inhibition of E. coli at 2.5 μg/mL. Cytotoxicity studies demonstrated low toxicity in HaCaT cells within the effective antibacterial concentration range. Conclusions: These findings highlight the potential of microwave-synthesized, photosensitizer-conjugated CDs as next-generation antimicrobial agents. This platform offers a cost-effective, sustainable, eco-friendly, and efficient platform for combating bacterial infections, with broader potential in pharmaceutical and biomedical applications. Full article

This study aimed to evaluate the physicochemical characterization and antibacterial activity of the essential oil (EO) extracted from the leaves of Mentha rotundifolia (L.) Huds. Molecular interactions between bioactive ligand compounds, target bacterial proteins and DNA gyrase subunit B (GyrB), as well as an in silico ADMET prediction study, were also conducted. The EO was obtained by hydrodistillation of the plant leaves. The Gas Chromatography–Tandem Mass Spectrometry (GC-MS/MS) analysis revealed Rotundifolone (27.95%) and carvacrol (19.48%) as the major constituents. Other components identified included Piperitenone (6.09%), Cinerolon (4.73%), and Pulegone (4.47%). Antibacterial activity was assessed against six bacterial strains: Enterococcus faecalis CIP 103214, Salmonella Typhi CIP 5535, Staphylococcus aureus ATCC 9144, Bacillus cereus ATCC 33019, Streptococcus agalactiae IPM 24842, and Providencia alcalifaciens CIP 82.90T. The disk diffusion assay showed a strong inhibitory effect against E. faecalis (inhibition zone: 19.66 ± 0.3 mm), while the lowest minimum inhibitory concentration (MIC) was observed for B. cereus (0.58 ± 0.01 µL/mL). The time-kill kinetics assay showed a progressive inactivation of all tested bacterial strains after their exposure to EO for 8 h at MICs. Furthermore, Molecular docking showed remarkable affinities between EO components, target proteins and DNA gyrase subunit B (GyrB). Moreover, the in silico ADMET predictions provided preliminary insights into the safety-related properties of the major EO components. In addition, EO compounds have the potential to interact with bacterial structures. These findings highlight the in vitro antibacterial potential of the M. rotundifolia EO and suggest its promise as a natural source of bioactive compounds. Full article

In this study, a hydrogel was developed based on a chondroitin sulfate–iron complex (CSFe) incorporated into a sodium alginate matrix. The CSFe complex was first prepared through the interaction of chondroitin sulfate (CS) with Fe³⁺ ions, achieving an iron content of 2.06%. Structural characterization confirmed that Fe³⁺ coordinated with the carboxyl, sulfate, and N-acetyl groups of CS, resulting in increased molecular weight and altered physicochemical properties. The CSFe complex exhibited significant antibacterial activity against Escherichia coli and Staphylococcus aureus (S. aureus), and was further incorporated into a sodium alginate matrix to form an injectable hydrogel with favorable physicochemical properties such as spreadability, shear-thinning behavior, and a compact porous microstructure. In a mouse model of S. aureus-infected wounds, the CSFe hydrogel significantly accelerated wound closure, reduced the levels of pro-inflammatory cytokines (TNF-α and IL-6), and increased the anti-inflammatory cytokine IL-10, indicating potent anti-infective and immunomodulatory functions. Overall, this work presents a multifunctional CSFe-incorporated hydrogel system that integrates antibacterial, anti-inflammatory, and tissue-regenerative properties, offering a promising strategy for infected wound healing and highlighting the potential of trivalent iron–polysaccharide coordination complexes in the development of advanced biomedical materials. Full article

Astrocaryum murumuru Mart., an Amazonian oilseed widely used for cosmetic oil production, generates large amounts of residual biomass that remains underexplored. In this study, ultrasound-assisted extraction (UAE) with ethanol as a green solvent was optimized using a Central Composite Rotational Design (CCRD) with 2 levels (2³) and 3 independent variables. The optimal condition (60 % ethanol, solid–liquid ratio 2.5 % m/v, 26 min) was determined using response surface methodology (RSM), and yielded 9.92 mg GAE/g of total phenolic content (TPC), with an experimental error of 5.34 % compared to the theoretical model prediction. Under this condition, total flavonoids and tannins were also quantified, reaching 0.38 ± 0.01 mg QE/g and 4.03 ± 0.10 mg TA/g, respectively. LC-MS analysis revealed a complex phenolic profile within the extract, confirming the efficiency of UAE in recovering bioactive molecules. Biological assays revealed significant functional properties. Antioxidant activity, evaluated by ABTS and DPPH methods, indicated that the extracts were effective radical scavengers. Antimicrobial assays showed only growth-selective inhibition against Staphylococcus aureus at concentrations of 2.5–20 mg/mL, while no significant activity was observed against Escherichia coli and Pseudomonas spp. These findings highlight the potential of A. murumuru biomass residues as a sustainable source of bioactive compounds with antioxidant activity and a growth inhibitor of S. aureus, reinforcing their possible application in the development of natural additives for food, while contributing to the sustainable bioeconomy of the Amazon. Full article

The avocado oil industry discards residues from the peeling and destoning steps primarily as mixtures with high biofunctional potential. Extracts from a residual avocado oil industry (RAOI) mixture were evaluated for the effects of green technologies Naviglio^® (rapid solid–liquid dynamic extraction), ultrasound, and maceration on their functional compounds and biological activity. The Naviglio^® extract excelled for total flavonoid content (7.29 ± 1.09 mg QE/g), minimum inhibitory concentration (MIC) against Escherichia coli (25 mg/mL) and Staphylococcus aureus (25 mg/mL), and minimum bactericidal concentration (MBC) against Staphylococcus aureus (50 mg/mL), with similar anti-inflammatory activity and total phenolic content (17.32 ± 0.59 mg GAE/g) than the maceration extract. Maceration was superior in seven polyphenol contents, β-sitosterol (9135.87 ± 468.83 mg/kg), and antioxidant activities (116.71 ± 16.09, 63.85 ± 3.97 and 49.63 ± 1.83 µmol TE/g for ABTS, FRAP and DPPH, respectively). At the evaluated MIC and MBC, the Naviglio^® extract was non-toxic, while maceration and ultrasound extracts were moderately toxic; at the anti-inflammatory concentrations tested, the Naviglio^® and ultrasound extracts were non-toxic. Naviglio^® and ultrasound extracts have pharmaceutical potential as antioxidants and anti-inflammatory agents, while the macerated extract is a potential source of β-sitosterol. For the first time, Naviglio^® technology was applied to RAOI mixtures, and the biological properties of the extracts were evaluated. Full article

The emergence of antimicrobial resistance and the increasing incidence of cancer have highlighted the urgent need to develop new drugs; therefore, the discovery of new bioactive molecules is an important goal for future research. In this study, freshwater fungi isolated from submerged Phragmites australis from Egypt were screened for antimicrobial and cytotoxic activities. Using ITS1 and ITS4 primers, eight frequently occurring Sordariomycetes taxa were identified and were then selected for further evaluation of bioactivity. Ethyl acetate crude extracts (A–H) were evaluated for antimicrobial activity using the agar disk-diffusion method. Extracts A and E, derived from Chaetomium globosum SCUF0000404 (PX596738) and Chaetomium madrasense SCUF0000401 (PX596735), respectively, showed broad-spectrum activity at 100 mg/mL against bacterial pathogens, including Staphylococcus aureus ATCC 29213 (15.33 and 18.00 mm), Streptococcus pyogenes ATCC 19615 (11.00 mm), Escherichia coli ATCC 35218 (10.33 and 10.67 mm), Klebsiella pneumoniae ATCC 700603 (14.00 and 16.67 mm), and Pseudomonas aeruginosa ATCC 27853 (13.33 and 16.33 mm), and show antifungal activity against Candida albicans ATCC 14053 (20.33 mm), Candida krusei ATCC 6258 (15.67 and 15.33 mm), Trichosporon asahii AMS 187 (17.00 and 17.67 mm), Exserohilum rostratum AMS 1077 (34.00 and 33.67 mm), and Trichophyton indotineae AMS 180 (38.33 and 34.00 mm). Selective cytotoxic effects on the breast cancer cell line MDA-MB-231 were observed by extracts A and E at IC₅₀ = 309 and 277 μg/mL, while non-selective cytotoxic effects on the normal HUVEC cell line were found with IC₅₀ = 919 and 796 μg/mL, respectively. Characterization of the most effective extracts A and E by high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) shows that they have a wide range of secondary metabolites, including cytochalasans, azaphilone alkaloids, steroids, terpenoids, flavonoids, and phenols. These findings underscore the chemical diversity and therapeutic potential of freshwater fungi from Egypt. Full article

To date, the problem of mastitis in cattle remains relevant for both the industrial sector and scientific research. Despite numerous active investigations, the causes of this disease have not been fully established. It is postulated that several factors may be involved, such as bacterial pathogens, animal husbandry practices, and weather and climatic conditions. In this study, we selected cows from farms in Yakutia to investigate microbial isolates present in the milk of cows affected by mastitis and treated with antibiotics. Five identified Staphylococcus aureus isolates were investigated using whole-genome sequencing (Illumina sequencing and nanopore sequencing), followed by analysis of virulence factors in the genomes and cultural properties of the isolates. The profile of S. aureus virulence genes (exotoxins, cytotoxins, superantigen-like proteins, adhesins) was identified via WGS. Hemolysin gene (hla) was detected in all isolates. An investigation of the cultural properties of the isolates, specifically through hemolysis of rabbit erythrocytes and Western blot analysis of the culture liquid of S. aureus, revealed different expression levels of alpha-hemolysin among the strains. One isolate (17-21) exhibited the highest secretion level of about 320 ± 37 ng, both in the hemolysis test and immunoblotting assay. An investigation of the isolates’ antibiotic resistance showed that all isolates exhibited multidrug resistance, as confirmed by the presence of antibiotic resistance genes in these isolates. One isolate (7-7) exhibited the broadest range of phenotypic resistance and was resistant to all tested antibiotics (except clindamycin). Phylogenetic analysis suggested that the evolution of these isolates occurred independently in their respective ecological niches, although their transfer from cattle to humans, and vice versa, is possible. Isolates 7-7, 18-22, 33-40, and 35-42 are most typical to Yakutian cattle, while isolate 17-21 might have been introduced from a different region. To the best of our knowledge, this is the first in-depth study into a range of S. aureus isolates associated with mastitis infection in Yakutian cattle. Full article

Green synthesis is an eco-friendly, simple, and cost-effective process for the synthesis of metal nanoparticles from plant extracts that are rich in bioactive compounds. In the current study, the antioxidant potential and total soluble polyphenol content (TPC) of different parts of Ligusticum mutellina (L.) Crantz were evaluated using DPPH (2,2-diphenyl-1-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) assays, and the results indicated that the seed extract was the most active plant part. HPLC analysis indicated the presence of phenolic compounds such as gallic acid, protocatechuic acid, and catechin, which may contribute to the reduction and stabilization of AgNPs. Silver nanoparticles (AgNPs) were synthesized from the aqueous seed extract of L. mutellina. The formation of nanoparticles was confirmed by UV–Vis spectroscopy, FT-IR analysis, powder X-ray diffraction (PXRD), and transmission electron microscopy (TEM). The UV–Vis spectrum indicated a surface plasmon resonance peak at around 411 nm, and PXRD analysis indicated an average crystallite size of around 13 nm. TEM analysis revealed predominantly spherical nanoparticles with an average size of 25.36 ± 10.76 nm. The synthesized AgNPs exhibited strong antibacterial activity against Gram-positive (Staphylococcus aureus and Bacillus subtilis) and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Overall, the results demonstrate that L. mutellina seed extract represents an effective natural source of reducing and stabilizing agents for green nanoparticle synthesis and highlight the potential of the obtained AgNPs as environmentally friendly antimicrobial materials. Full article

Photothermal therapy is a highly promising non-invasive treatment strategy, but its clinical application is still limited by issues such as insufficient light-to-heat conversion efficiency and potential biological toxicity. To address these challenges, this study employed a biomineralization strategy to synthesize gold nanoflowers (Van@Au₄ NFs) using vancomycin as a template. The synthesized Van@Au₄ NFs exhibited a uniform flower-like morphology with a hydrodynamic diameter of approximately 122 nm. Under 808 nm laser irradiation, this material demonstrated excellent photothermal properties, with a photothermal conversion efficiency of 34.94%, and remained stable after four cold-hot cycles. The introduction of vancomycin effectively enhanced the colloidal stability and photothermal conversion ability of the nanoflowers. In vitro experiments showed that Van@Au₄ NFs had an inhibition rate of 90.8% against Staphylococcus aureus and 95.18% against A549 tumor cells under near-infrared light irradiation. This study constructed an efficient photothermal agent, providing important experimental evidence for in vitro synergistic photothermal treatment of bacterial infections and tumors. Full article

The interest in the use of phytochemicals and herbal medicines for the treatment of acne vulgaris has grown steadily over recent decades. The research on the secondary metabolites and biological properties of bearberry (Arctostaphylos uva-ursi (L.) Spreng.) has been intensified in recent years, but the range of bacterial strains tested, many of which are highly relevant to human health, remains very limited. Therefore, the aim of this study was to evaluate the chemical composition and the antioxidant, antimicrobial, and cytotoxic activities of water and ethanolic bearberry leaf extracts. Compared with the ethanolic extract, the water extract was characterized by higher concentrations of arbutin, hydroquinone, corilagin, and hyperoside and the absence of ursolic acid and oleanolic acid. However, it exhibited lower total phenolic content and reduced levels of penta-O-galloyl-β-d-glucose (PGG). The ethanolic extract of bearberry leaves showed higher antioxidant activity and the most favorable overall biological properties. The therapeutic index (TI) values for the water and ethanolic extracts, respectively, were as follows: Cutibacterium acnes ATCC 11827 (10.70; 21.57), Propionibacterium acnes PCM 2334 (10.70; 43.13), P. acnes PCM (5.33; 21.57), Staphylococcus aureus ATCC 25923 (10.70; 21.57), and S. epidermidis ATCC 12228 (5.33; 10.78). The present findings further support the medicinal and cosmetic use of A. uva-ursi and highlight its potential as a source of natural antibacterial agents for acne treatment. Full article

Foodborne diseases represent a major public health concern, particularly those associated with dairy products contaminated with Staphylococcus aureus, a pathogen capable of producing heat-stable enterotoxins. This study evaluated the potential of native lactic acid bacteria (LAB) isolated from artisanal kefir grains as natural biocontrol agents in fermented dairy foods. Kefir grains obtained from three artisanal producers were microbiologically characterized, revealing LAB as the dominant group and the absence of Enterobacteriaceae. Strains belonging mainly to the genera Lactobacillus sensu lato, Leuconostoc, and Pediococcus were isolated and exhibited differentiated metabolic profiles. Safety assessment showed no hemolytic activity and an overall susceptibility to clinically relevant antibiotics, although genus-dependent intrinsic resistance patterns were observed. Several strains displayed enzymatic activities related to carbohydrate digestion and high tolerance to simulated gastrointestinal conditions, with survival rates exceeding 90% during both gastric and intestinal phases. Neutralized cell-free supernatant (CFS) demonstrated differential inhibitory activity, with significant antagonism of S. aureus and E. coli, comparable to those of commercial reference strains. In a yogurt model system stored at 4 °C, selected Lactobacillus and Pediococcus strains induced a progressive and significant reduction in S. aureus populations, achieving complete elimination to undetectable levels in shorter times than commercial probiotic strains. Overall, these results demonstrate that native LAB from artisanal kefir grains exhibit an adequate safety and functional profile, together with strong antagonistic activity, supporting their potential application as natural protective cultures to improve the food hygiene of fermented dairy products. Full article

This study was carried out to investigate the antimicrobial performance and color stability of silver (Ag)-modified polyurethane and waterborne coating systems applied to Oriental beech (Fagus orientalis L.) wood after the specimens were subjected to UV aging for 24 h. Antimicrobial activity and color stability were evaluated before and after aging against Escherichia coli (E. coli, ATCC 25922), Staphylococcus aureus (S. aureus, NCTC 13552), and Candida albicans (C. albicans) in accordance with the JIS Z 2801 standard. Color changes were determined using CIELab parameters (ΔL*, Δa*, Δb*, and ΔE*) in accordance with the TS EN ISO 16474-3 standard. Prior to UV exposure, the highest antibacterial activity against E. coli occurred in Ag-modified waterborne varnish coatings, whereas the highest antifungal activity against C. albicans occurred in Ag-modified polyurethane paint systems. After UV aging, antimicrobial performance varied depending on the coating type. Particularly, Ag-modified waterborne varnish coatings retained significant antibacterial activity against E. coli and S. aureus and exhibited the highest antifungal performance against C. albicans. Color analysis revealed that UV exposure also caused significant changes in all coating systems. The most pronounced variations were observed for the lightness difference (ΔL*), red–green color difference (Δa*), and yellow–blue color difference (Δb*) parameters, while the lowest total color difference (ΔE*) values were observed for Ag-modified polyurethane and Ag-modified waterborne varnish coatings. Overall, Ag-modified waterborne varnish systems demonstrated superior performance in both antimicrobial activity and color stability after UV aging. Full article

Streptococcus suis is a serious zoonotic pathogen responsible for rapid progression and deadly infections in both humans and pigs. With an increasing number of reported cases and considering the limitations of standard routine identification, a simple, rapid, and cost-effective approach is needed. In this study, a label-free colorimetric assay based on gold nanoparticles (AuNPs) was applied with a specific aptamer, R8-su12. This assay offered simplified detection through observable color change, enabling visual analysis by the naked eye or assessment via UV–Vis spectrophotometry. Under the optimal assay conditions, the detection procedure was carried out within 45 min. The reaction of the aptasensor and other bacterial species, including Staphylococcus aureus, S. pneumoniae, S. pyogenes, Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecium, and E. faecalis, was not present, indicating the specificity of this assay. Moreover, the aptasensor exhibited high sensitivity with a limit of detection (LOD) at 1 CFU of S. suis and had broad reactivity with S. suis serotypes 1, 1/2, 9, and 14, as well as with S. suis isolated from clinical specimens. Thus, this aptasensor demonstrates proof-of-concept feasibility including clinical sample testing before practical implementation. It holds promise as a practical tool for the early screening and outbreak management of S. suis in a variety of settings, such as clinical laboratories, food safety, and the environment. Full article

Background/Objectives: Staphylococcus aureus (S. aureus) intramammary infection remains a major global dairy problem due to its contagious nature, its ability to persist and colonize teat/skin and mucosal niches, and the often-limited bacteriological cure achieved with antimicrobial therapy. Beyond udder health, it is relevant to public health because it can enter raw milk chains and serve as a reservoir for antimicrobial resistance determinants that may circulate between dairy animals and humans. Methods: We assessed S. aureus’ ecology in raw ewe milk from 75 sheep farms in Epirus (Greece) by sampling clinically healthy controls (group A) and clinical mastitis cases pre-treatment (group B), followed by resampling at the first post-withdrawal milking after penicillin/streptomycin treatment (group C1—therapeutic protocol 1), oxytetracycline treatment (group C2—therapeutic protocol 2), or enrofloxacin treatment (group C3—therapeutic protocol 3). Results: S. aureus detection was high and comparable across groups (A 23.0%, B 22.0–30.0%, C 20.0–22.0%), and paired analyses showed no significant pre–post shifts in detection/burden within therapeutic protocols (all p > 0.05). Nevertheless, persistence remained evident. The chromosomal gene mecA was detected in S. aureus strains in all groups, ranging from 13.6% in controls to 54.5% post-withdrawal in group C1, and was also present in the pre-treatment group. In paired sampling animals, mecA was mostly stable, with rare emergence or loss. Across antibiotic classes, within-animal resistance transitions were generally uncommon and non-significant (p > 0.05); β-lactam resistance was fully stable (p = 1.00). Descriptively, resistance to protein synthesis inhibitors tended to decline after therapy in protocol 1 and protocol 3, while protocol 3 showed post-treatment gains in fluoroquinolone resistance. By contrast, virulence-associated phenotype traits shifted after therapy: enterotoxigenicity increased post-withdrawal (especially in the C3 group), Staphylococcal Enterotoxin A (SEA) and Staphylococcal Enterotoxin B (SEB) appeared only post-therapy, Staphylococcal Enterotoxin D (SED) increased significantly in paired isolates (p = 0.002), and strong biofilm adherence increased (in C3, p = 1.5 × 10⁻⁵). Conclusions: The detection of S. aureus after therapy suggests that one possibility is that antimicrobial exposure may select for, or otherwise reshape, the residual intramammary population, rather than reliably eliminating it—an outcome that remains clinically relevant for udder health. Moreover, the persistence of mecA/methicillin-resistant Staphylococcus aureus (MRSA)-compatible profiles indicates that milk released to the food chain after withdrawal compliance may still harbor S. aureus with enhanced preservation capacity and significant food safety relevance. Full article