Search Results (854)

Combining antibiotics with propolis is an effective method to combat bacterial drug resistance. Nanoparticles are of interest in the antimicrobial field because of their higher drug stability, solubility, penetration power, and treatment efficacy. In this study, propolis nanoparticles (PNPs) were synthesized, and their antibacterial and anti-biofilm activities against methicillin-resistant Staphylococcus aureus (MRSA) in combination with ampicillin sodium (AS) were analyzed. The PNPs had an average particle diameter of 118.0 nm, a polydispersity index of 0.129, and a zeta potential of −28.2 mV. The fractional inhibitory concentration indices of PNPs and AS against tested MRSA strains highlighted this synergy, ranging between 0.375 and 0.5. Crystal violet staining showed that combined PNPs and AS significantly inhibited biofilm formation and reduced existing biofilm biomass. We then discovered that PNPs inhibited bacterial adhesion, extracellular polysaccharide synthesis, and mecR1, mecA, blaZ, and icaADBC gene expression. These results indicated that PNPs exerted a synergistic antibacterial effect with AS by inhibiting mecR1, mecA, and blaZ gene expressions to reduce the drug resistance of MRSA. Meanwhile, PNPs weakened bacterial adhesion and aggregation by suppressing icaADBC gene expression, allowing antibiotics to penetrate the biofilm, and exhibiting significant synergistic anti-biofilm activity. In summary, PNPs are promising candidates for combating MRSA-related diseases. Full article

The escalating global challenges of antimicrobial resistance (AMR) and cancer necessitate innovative therapeutic solutions from natural sources. This study investigated the multifaceted therapeutic potential of pigment-enriched plant extracts. We screened diverse plant extracts for antimicrobial and antibiofilm activity against multidrug-resistant bacteria and fungi. Hibiscus sabdariffa emerged as the most promising, demonstrating potent broad-spectrum antimicrobial and significant antibiofilm activity. Sub-inhibitory concentrations of H. sabdariffa robustly downregulated essential bacterial virulence genes and suppressed aflatoxin gene expression. Comprehensive chemical profiling via HPLC identified major anthocyanin glucosides, while GC-MS revealed diverse non-pigment bioactive compounds, including fatty acids and alcohols. Molecular docking suggested favorable interactions of key identified compounds (Cyanidin-3-O-glucoside and 1-Deoxy-d-arabitol) with E. coli outer membrane protein A (OmpA), indicating potential antiadhesive and antimicrobial mechanisms. Furthermore, H. sabdariffa exhibited selective cytotoxicity against MCF-7 breast cancer cells. These findings establish H. sabdariffa pigment-enriched extract as a highly promising, multi-functional source of novel therapeutics, highlighting its potential for simultaneously addressing drug resistance and cancer challenges through an integrated chemical, biological, and computational approach. Full article

Toothpaste is an essential oral hygiene product commonly used to sustain oral health due to its incorporation of antimicrobial agents. Numerous functional toothpastes enriched with antimicrobial agents have been developed and are available to consumers. This study evaluates the antimicrobial and antibiofilm efficacy of 12 commercially available toothpaste products, including those with specialized functions. Statistical significance was assessed to validate the differences observed among the toothpaste samples. Their effects on Streptococcus mutans, the primary pathogen responsible for dental caries, were evaluated. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined, and bacterial growth was measured to compare antimicrobial activities. Toothpaste containing 1000 μg/mL fluoride and whitening toothpaste exhibited the strongest antimicrobial effects, effectively inhibiting S. mutans growth. Additionally, bamboo salt-enriched and tartar-control toothpaste demonstrated inhibitory effects on bacterial growth. Assays to evaluate the ability of cells to form biofilms and the expression of genes involved in biofilm formation revealed a partial correlation between biofilm formation and spaP, gtfB, gtfC, and gtfD expression, although some showed opposite trends. Collectively, this study provides valuable insights into the antimicrobial and biofilm inhibition capabilities of commercial toothpastes against S. mutans, offering a foundation for evaluating the efficacy of functional toothpaste products. Full article

Background/Objectives: The growing demand for biocompatible and fluoride-free alternatives in oral care has led to the development of formulations containing nano-hydroxyapatite (nanoHAP). This study aimed to evaluate the antimicrobial, antibiofilm, antioxidant, and anti-inflammatory properties of a novel mouthwash containing nanoHAP, zinc lactate, D-panthenol, licorice extract, and cetylpyridinium chloride, with particular focus on its efficacy against Staphylococcus aureus and its biofilm on various dental materials. Methods: The antimicrobial activities of the mouthwash KWT0000 and control product ELM were assessed via minimal inhibitory concentration (MIC) testing against selected Gram-positive and Gram-negative bacteria and Candida fungi. Antibiofilm activity was evaluated using fluorescence and digital microscopy following 1-h exposure to biofilms of Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans. The efficacy was compared across multiple dental materials, including titanium, zirconia, and PMMA. Antioxidant capacity was determined using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) assay, and anti-inflammatory potential via hyaluronidase inhibition. Results: KWT0000 exhibited strong antimicrobial activity against S. aureus and C. albicans (MICs: 0.2–1.6%) and moderate activity against Gram-negative strains. Fluorescence imaging revealed significant biofilm disruption and bacterial death after 1 h. On metallic surfaces, especially polished titanium and zirconia, KWT0000 reduced S. aureus biofilm density considerably. The formulation also demonstrated superior antioxidant (55.33 ± 3.34%) and anti-inflammatory (23.33 ± 3.67%) activity compared to a fluoride-based comparator. Conclusions: The tested nanoHAP-based mouthwash shows promising potential in antimicrobial and antibiofilm oral care, particularly for patients with dental implants. Its multifunctional effects may support not only plaque control but also soft tissue health. Full article

Antimicrobial resistance (AMR) has emerged as a global health crisis, with methicillin-resistant Staphylococcus aureus (MRSA) representing one of the most clinically significant multidrug-resistant pathogens. In this study, three structurally unique anthracycline derivatives—keto-ester (1), 4-deoxy-ε-pyrromycinone (2), and misamycin (3)—were first isolated and characterized from the fermentation broth of the marine-derived Streptomyces tauricus NBUD24. These compounds exhibited notable antibacterial efficacy against MRSA, with minimum inhibitory concentrations (MICs) ranging from 16 to 32 µg/mL. Cytotoxicity assays confirmed their safety profile at therapeutic concentrations. The biofilm formation assay demonstrated that 4-deoxy-ε-pyrromycinone inhibited biofilm formation of MRSA ATCC43300, with an inhibition rate of 64.4%. Investigations of antibacterial mechanisms revealed that these compounds exert antibacterial effects primarily through disruption of bacterial cell wall integrity and destruction of DNA structure. These findings underscore the potential of marine-derived microbial metabolites as promising scaffolds for developing next-generation antimicrobial candidates to combat drug-resistant infections. Full article

Pastinaca L. is a small genus belonging to the Apiaceae family, traditionally used for both nutritional and medicinal purposes. Pastinaca sativa L. subsp. sativa is a biennial plant widely distributed in Europe and Asia, with recognized ethnopharmacological relevance. In this study, the essential oil (EO) obtained from the aerial parts of P. sativa subsp. sativa, collected in Alto Adige (Italy)—a previously unstudied accession—was analyzed by GC-MS, and the volatile profile has been compared with that of EOs previously studied in Bulgaria and Serbia. The EO was found to be rich in octyl acetate (38.7%) and octyl butanoate (26.7%), confirming that this species biosynthesizes these natural esters. The EO and its main constituents were tested to evaluate their antimicrobial properties. Furthermore, their biological potential was evaluated through antimicrobial, antibiofilm and antioxidant assays. This research work, in addition to evaluating possible chemotaxonomic differences at the geographical level of EOs of Pastinaca sativa subsp. sativa, has been extended to the determination of the biological properties of this accession never investigated before, with the aim of acquiring a broader vision of biofilm and antibacterial properties. Full article

Daucus is a large genus of the Apiaceae family, comprising around forty-five accepted species, that has a worldwide distribution. Species of this genus have been reported to have several traditional medicinal uses, and some of them are also largely used as food and spices. Daucus nebrodensis Strobl. is an endemic species of Sicily growing in the montane environments of the Madonie and the Nebrodi Mountains. In this work, the essential oil of D. nebrodensis (DnEO), collected wild near Messina (Italy), was chemically and biologically investigated. The hydrodistilled essential oil (yield 0.15%), obtained from fresh aerial parts, was evaluated by GC-MS, and It was particularly rich in monoterpene hydrocarbons, with sabinene (33.6%), α-pinene (17.2%), γ-terpinene (9.8%), and α-terpinene (7.6%) as the main metabolites. DnEO, and its main constituents, have been tested to evaluate their biological properties. Given the current problem of antibiotic resistance, it is of great interest to identify alternative molecules that could counteract the its progression. Therefore, DnEO was tested against Gram-negative species, such as E. coli DH5α and P. aeruginosa PAOI, and Gram-positive species, such as S. aureus ATCC6538P, B. subtilis AZ54, and M. smegmatis MC²155, showing notable antibacterial activity. The MIC for Bacillus subtilis, the most sensitive strain, was 18 mg/mL, while the MIC for Pseudomonas aeruginosa, the least sensitive strain, was 30 mg/mL. Moreover, interesting antibiofilm activity was observed against Mycobacterium smegmatis with a 55% inhibition. Its ability to form biofilms contributes to its persistence and resistance in clinical settings. These findings highlight the potential of D. nebrodensis EO as a source of bioactive compounds with promising antimicrobial and antibiofilm properties. Full article

Pseudomonas aeruginosa biofilm formation is critical to antibiotic resistance and persistence. Targeting cyclic di-GMP (c-di-GMP) signaling, a master biofilm formation and virulence regulator, presents a promising strategy to combat resistant bacterial infections. Myricetin, a natural polyphenolic flavonoid with documented antimicrobial and anti-biofilm activities, may enhance antibiotic efficacy against Pseudomonas aeruginosa. This study evaluated the synergistic effects of myricetin combined with azithromycin, ciprofloxacin, or cefdinir against both standard and drug-resistant Pseudomonas aeruginosa strains. Antibacterial activity, biofilm disruption, and motility inhibition were experimentally assessed, while molecular dynamic (MD) simulations elucidated myricetin’s molecular mechanism of action. Our results suggested that myricetin synergistically potentiated all three antibiotics, reducing c-di-GMP synthesis by 28% (azithromycin), 57% (ciprofloxacin), and 30% (cefdinir). It enhanced bactericidal effects, suppressed biofilm formation, and impaired swimming, swarming, and twitching motility. Computational analyses revealed that myricetin binds allosterically to FimX very well, a key regulator in the c-di-GMP signaling pathway. Hence, myricetin may act as a c-di-GMP inhibitor, reversing biofilm-mediated resistance in Pseudomonas aeruginosa and augmenting antibiotic efficacy. This integrated experimental and computational approach provides a framework for developing anti-virulence and antibiotic combination therapies against recalcitrant Gram-negative pathogens. Full article

The increasing circulation of multi-drug-resistant pathogens, coupled with the sluggish development of new antibiotics, is weakening our capacity to combat human infections, resulting in elevated death tolls. To address this worldwide crisis, antimicrobial peptides (AMPs) are viewed as promising substitutes or adjuvants for combating bacterial infections caused by multidrug-resistant organisms. Here, the antimicrobial activity and structural characterization of a novel 13-amino acid cationic peptide named RKW (RKWILKWLRTWKK-NH2), designed based on known AMPs sequences and the identification of a key tryptophan-rich structural motif, were described. RKW displayed a broad-spectrum and potent antimicrobial and antibiofilm activity against Gram-positive and Gram-negative pathogens, including ESKAPE bacteria and fungi with minimal inhibitory concentrations (MBC) ranging from 5 µM to 20 μM. Structural results by fluorescence and Circular Dichroism (CD) spectroscopy revealed that the peptide was folded into a regular α-helical conformation in a membrane-like environment, remaining stable in a wide range of pH and temperature for at least 48 h of incubation. Furthermore, RKW showed low toxicity in vitro against mammalian fibroblast cells, indicating its potential as a promising candidate for the development of new antimicrobial or antiseptic strategies. Full article

The emergence of antimicrobial resistance and the increasing demand for a healthier lifestyle have set new goals for science and industry. In the search for new, more effective, and environmentally friendly antimicrobial agents, special attention is being paid to natural resources. In this regard, essential oils derived from plants, which are widely used in the cosmetic, food, and pharmaceutical industries, are one of the solutions. In view of the above, this study aims to investigate the biological effects of Abies alba essential oil (AAEO). The chemical profile of AAEO was evaluated by GC/MS analysis, which revealed a high abundance of limonene (52.2%) and α-pinene (36.2%). Antioxidant activity evaluation showed a higher potential of AAEO in scavenging ABTS radical species with an IC₅₀ value of 1.18 ± 0.05 mg/mL. In vitro antimicrobial activity was determined by disc diffusion and minimum inhibitory concentration assays and showed that AAEO was more efficient in inhibiting the growth of G⁺ bacterial species. On contrary, in situ evaluations of antimicrobial effects of AAEO on different food models (strawberry, kiwi, white radish, and beetroot) resulted in more efficient suppression of G⁻ bacterial species. Although AAEO showed low effects on yeasts determined by in vitro methods, in situ investigations showed its higher potential in eradication of Candida yeast. The antibiofilm properties of the AAEO matrix were determined by means of crystal violet assay and MALDI-TOF MS Biotyper analysis against biofilm-forming Salmonella enterica. The analysis performed led to the conclusion that AAEO, when applied prior to biofilm formation, may contribute to the removal of planktonic cells and alter the abiotic surface, thereby reducing the suitability of Salmonella enterica for microbial attachment. Full article

Microbial biofilms present a formidable challenge in ophthalmology. Their intrinsic resistance to antibiotics and evasion of host immune defenses significantly complicate treatments for ocular infections such as conjunctivitis, keratitis, blepharitis, and endophthalmitis. These infections are often caused by pathogens, including Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, particularly in patients using contact lenses or intraocular implants—devices that serve as surfaces for biofilm formation. The global rise in antimicrobial resistance has intensified the search for alternative treatment modalities. In this regard, plant-derived antimicrobials have emerged as promising candidates demonstrating broad-spectrum antimicrobial and antibiofilm activity through different mechanisms from those of conventional antibiotics. These mechanisms include inhibiting quorum sensing, disrupting established biofilm matrices, and interfering with microbial adhesion and communication. However, the clinical translation of phytochemicals faces significant barriers, including variability in chemical composition due to environmental and genetic factors, difficulties in standardization and reproducibility, poor water solubility and ocular bioavailability, and a lack of robust clinical trials evaluating their efficacy and safety in ophthalmic settings. Furthermore, regulatory uncertainties and the absence of unified guidelines for approving plant-derived formulations further hinder their integration into evidence-based ophthalmic practice. This review synthesizes the current knowledge on the pathogenesis and treatment of biofilm-associated ocular infections, critically evaluating plant-based antimicrobials as emerging therapeutic agents. Notably, resveratrol, curcumin, abietic acid, and selected essential oils demonstrated notable antibiofilm activity against S. aureus, P. aeruginosa, and C. albicans. These findings support the potential of phytochemicals as adjunctive or alternative agents in managing biofilm-associated ocular infections. By highlighting both their therapeutic promise and translational limitations, this review contributes to the ongoing discourse on sustainable, innovative approaches to managing antibiotic-resistant ocular infections. Full article

Canine otitis externa is a prevalent condition, and inadequate treatment may favor the emergence of multidrug-resistant microorganisms. Drug repurposing provides an alternative approach for the management of this disease. Thus, this study aimed at assessing the antimicrobial and antibiofilm properties of levamisole against bacterial strains recovered from dogs with otitis externa as well as its influence on biofilm growth dynamics during 120 h. A total of 50 clinical bacterial isolates were subjected to analysis. Planktonic bacterial susceptibility to levamisole was assessed by broth microdilution to determine the minimum inhibitory concentration (MIC), the lowest concentration that completely inhibits bacterial growth. The activity against mature biofilms was assessed by determining the minimum biofilm eradication concentration (MBEC). The effect of levamisole on biofilm formation was evaluated at the MIC and at two subinhibitory concentrations, with daily readings recorded at 48, 72, 96, and 120 h. MICs of levamisole ranged from 0.58 to 2.34 mg/mL. Levamisole reduced the biomass of mature biofilms (p < 0.05), with MBEC values ranging from 1.17 to 18.75 mg/mL, and biofilm formation was significantly reduced at the MIC concentration (1.17 mg/mL) for all isolates for 120 h (p < 0.05). Levamisole demonstrated potential as a preventive approach against biofilm-associated bacterial otitis. Full article

The growing threat of antibiotic-resistant Gram-negative bacteria highlights the urgent need for innovative, non-bactericidal therapeutic strategies. Quorum-sensing (QS) inhibition has emerged as a promising approach to attenuate bacterial virulence without exerting selective pressure. This study evaluated the antimicrobial, anti-QS, and antibiofilm properties of aqueous extracts from five medicinal plants native to northeastern Mexico: Gymnosperma glutinosum, Ibervillea sonorae, Larrea tridentata, Olea europaea, and Tecoma stans. Disk diffusion and violacein quantification assays using Chromobacterium violaceum demonstrated significant QS inhibition by G. glutinosum and T. stans, with violacein reductions of 60.02% and 52.72%, respectively, at 40 mg/mL. While L. tridentata and O. europaea exhibited antibacterial activity, I. sonorae showed no growth or pigment inhibition but achieved the highest biofilm disruption (89.89%) against Salmonella typhimurium. UPLC-MS analysis identified chlorogenic acid, kaempferol, and D-(−)-quinic acid as major constituents, compounds previously associated with QS modulation. These findings highlight the potential of traditional Mexican plant species as sources of QS inhibitors and bio-film-disrupting agents, supporting their further development as alternatives to conventional antibiotics. Full article

Mannoproteins are structural components of the yeast cell wall exhibiting extensive functionality applicable to the food, feed, and medical industries. They are characterized mostly by immunostimulatory, prebiotic, antimicrobial, antibiofilm, antioxidant, and emulsifying properties. The bioactive properties of mannoproteins underscore their significance in functional food production, therapy, and animal husbandry. This review critically examines the literature on yeast mannoproteins, focusing on their chemical characteristics, biological activity, and potential applications. Considering gaps in the literature data regarding detailed chemical characterization and mechanisms of action of mannoproteins, future research should aim at precise structural analysis, particularly of mannoproteins derived from nonconventional yeast, to uncover new potential industrial and health applications. Full article

Klebsiella pneumoniae can acquire resistance mechanisms to colistin and present a pan-resistant phenotype. Therefore, new alternative agents are imperative to control this pathogen, and the peptide Jelleine-I stands out as a promising prototype. Here, the antibacterial activity of Jelleine-I against clinical isolates of colistin-resistant K. pneumoniae (CRKP) was investigated. Antimicrobial activity was assessed by determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time kill-curve assay. The release of 260 nm-absorbing materials (DNA/RNA) and the release of proteins were used in the lysis assay. Anti-biofilm activity was studied in microplates. In vivo activity was determined by the lethality assay using Tenebrio molitor larvae. The results show that the MIC of Jelleine-I ranged from 16 to 128 µM and the MBC was on average 128 µM. Jelleine-I at 200 µM killed all CRKP cells in suspension (10⁶ colony-forming units (CFU)/mL) after 150 min of incubation. Jelleine-I acts on the CRKP cell membrane inducing lysis. Biomass and viability of CRKP-induced biofilms are reduced after treatment with Jelleine-I, and the use of this peptide in T. molitor larvae infected with CRKP reduces lethality and improves overall larval health. In conclusion, Jelleine-I is a potential prototype for the development of new antimicrobial agents. Full article