Search Results (132)

Cytokinins, plant hormones derived from adenine, are best known for regulating growth and stress responses in plants. Recent findings suggest they may also influence microbial viability, yet their direct antimicrobial potential remains underexplored. This study evaluates the antimicrobial activities of four natural cytokinins (iPA, B, K, and p-T) and their N⁹-ribosides (iPAR, BR, KR, and p-TR) against selected human pathogens. Using the broth microdilution method, we assessed their effects on Gram-positive and Gram-negative bacteria, as well as fungal strains. While Gram-negative species showed no susceptibility, all tested compounds exhibited bacteriostatic activity against Bacillus subtilis and Enterococcus faecalis. Most notably, kinetin (K) and kinetin riboside (KR) displayed strong antifungal activity against Candida albicans, with MIC values comparable to the reference drug nystatin. Molecular docking studies supported these findings by showing that K and KR form favorable interactions with two validated antifungal targets in Candida albicans: secreted aspartic proteinase 3 (SAP3) and dihydrofolate reductase (DHFR). This is, to our knowledge, the first report linking natural cytokinins to direct antifungal action against C. albicans supported by in silico evidence. These findings highlight the potential of K and KR as promising leads for the development of cytokinin-based antifungal agents. Full article

The search for natural antimicrobials has intensified with rising food safety demands. This study evaluated 23 probiotic strains, identifying Bifidobacterium sp. strain TF04 as a potent inhibitor against pathogens, with inhibition zone diameters of 12.85 ± 0.12 mm (Escherichia coli), 14.85 ± 0.10 mm (Staphylococcus aureus), and 17.50 ± 0.23 mm (Staphylococcus epidermidis). Preliminary analysis shows that the main antibacterial compounds produced by TF04 in the process of bacterial growth inhibition are antibacterial active proteins. TF04 exhibits optimal bacteriostatic activity within the pH range of 2–4, with a notable decline in effectiveness as the pH value increases. At the same time, the bacteriostat produced by TF04 showed strong thermal stability and ultraviolet stability. TF04 demonstrated excellent probiotic potential: surviving acidic (pH 2.0, >45% viability) and bile conditions (3% bile salts, >55% survival). It showed strong auto-aggregation (40.10%) and hydrophobicity (>30%), indicating gut colonization potential, along with notable antioxidant capacity. Safety was confirmed by absent hemolytic and gelatinase activities. These properties position TF04 as a promising multifunctional candidate for food preservation, combining antimicrobial efficacy with probiotic benefits. Further studies will purify its bioactive compounds and validate applications in food systems. Full article

Melittin, a naturally occurring antimicrobial peptide, demonstrates broad-spectrum activity, effectively suppressing and eliminating both Gram-positive and Gram-negative bacteria, including specific drug-resistant strains. In this study, molecular simulation software was employed to investigate and modify the structure of melittin with the aim of synthesizing a modified peptide exhibiting enhanced antibacterial potency and assessing its bacteriostatic and antibacterial properties. The primary research objectives were as follows: 1. Preparation and characterization of melittin-modified peptide—Using molecular simulation software, the structure of the melittin-modified peptide was adjusted to predict its activity and select the most appropriate amino acid sequence. The peptide was synthesized through solid-phase peptide synthesis employing the Fmoc strategy and subsequently purified using liquid chromatography. The yield of the purified modified melittin was determined to be 30.97%, and the identity of the product was confirmed by LC-MS and MALDI-TOF-MS. 2. Evaluation of the antimicrobial activity of the melittin-modified peptide—The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of melittin and its modified peptide were measured using gradient dilution and plate counting techniques. The results revealed that both melittin and its modified peptide exhibited strong antibacterial efficacy against Gram-positive and Gram-negative bacteria, as well as certain drug-resistant strains. This showed that melittin and its modified peptide have the same antibacterial (killing) effect. A scanning electron microscope analysis indicated that both melittin and its modified peptide were capable of disrupting bacterial cell structures, leading to bacterial cell death. Full article

The aim of this review is to list the various natural sources of antimicrobials that are readily available. Indeed, many plant sources are known to have antibiotic properties, although it is not always clear which molecule is responsible for this activity. Many food supplements also have this therapeutic indication. We propose here to take stock of the scientific knowledge attesting or not to these indications for some food sources. An overview of the various antibiotic drugs commercially available will be provided. A structural indication of the natural molecules present in various plants and reported to contribute to their antibiotic power will be given. The plants mentioned in this review, which does not claim to be exhaustive, are referenced for fighting Gram-positive and/or Gram-negative bacteria. It is difficult to attribute activity to just one of these natural molecules, as it is likely to result from synergy within the plant. Similarly, chitosan is mentioned for its fungistatic and bacteriostatic properties. In this case, this polymeric compound derived from the chitin of marine organisms is referenced for its antibiofilm activity. It seems that, in the face of growing antibiotic resistance, it makes sense to keep high-performance synthetic antibiotics on hand to treat the difficult pathologies that require them. On the other hand, for minor infections, the use of better-tolerated natural sources is certainly sufficient. To achieve this, we need to take stock of common plant sources, available as food products or dietary supplements, which are known to be active in this field. Full article

Currently, problems related to antibiotic resistance are shifting the focus of pharmaceutical research towards natural molecules with antibacterial properties. Among them, flavonoids represent promising molecules with strong antibacterial features; however, they have poor biopharmaceutical properties. In this study, we developed solid lipid nanoparticles (SLNs) loaded with the flavanone naringenin (NRG) to offer an option for treating bacterial infections. NRG-SLNs systems were prepared by a solvent emulsification/diffusion and ultrasonication method, using Compritol^® 888 ATO (COM) as the lipid. The optimal formulation was obtained using a 10% (w/w) theoretical amount of NRG (NRG₁₀-SLNs), exhibiting homogeneous sizes (approximately 50 nm and 0.15 polydispersity index), negative zeta potential (−30 mV), and excellent encapsulation parameters (an encapsulation efficiency percentage of 97.9% and a drug content of 4%). NRG₁₀-SLNs presented good physical stability over 4 weeks. A cumulative drug release of 55% in 24 h and the prolonged release of the remaining amount over 10 days was observed. In addition, µ-Raman spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction measurements were carried out to characterize the drug–lipid interactions. Finally, the in vitro antibacterial and antibiofilm activities of NRG₁₀-SLNs were assayed and compared to free NRG. NRG₁₀-SLNs were bacteriostatic against Staphylococcus aureus, including the methicillin-resistant S. aureus (MRSA) and Escherichia coli strains. An improvement in the antibacterial activity of NRG-loaded SLNs compared to the free molecule was observed against S. aureus strains, probably due to the interaction of the surfactant-coated SLNs with the bacterial surface. A similar trend was observed for the biofilm inhibition. Full article

Chitosan is a positively charged natural polymer with several properties conducive to wound-healing applications, such as biodegradability, structural integrity, hydrophilicity, adhesiveness to tissue, and bacteriostatic potential. Along with other mechanical properties, some of the properties discussed in this review are antibacterial properties, mucoadhesive properties, biocompatibility, high fluid absorption capacity, and anti-inflammatory response. Chitosan forms stable complexes with oppositely charged polymers, arising from electrostatic interactions between (+) amino groups of chitosan and (−) groups of other polymers. These polyelectrolyte complexes (PECs) can be manufactured using various materials and methods, which brings a diversity of formulations and properties that can be optimized for specific wound healing as well as other applications. For example, chitosan-based PEC can be made into dressings/films, hydrogels, and membranes. There are various pros and cons associated with manufacturing the dressings; for instance, a layer-by-layer casting technique can optimize the nanoparticle release and affect the mechanical strength due to the formation of a heterostructure. Furthermore, chitosan’s molecular weight and degree of deacetylation, as well as the nature of the negatively charged biomaterial with which it is cross-linked, are major factors that govern the mechanical properties and biodegradation kinetics of the PEC dressing. The use of chitosan in wound care products is forecasted to drive the growth of the global chitosan market, which is expected to increase by approximately 14.3% within the next decade. This growth is driven by products such as chitoderm-containing ointments, which provide scaffolding for skin cell regeneration. Despite significant advancements, there remains a critical gap in translating chitosan-based biomaterials from research to clinical applications. Full article

Critical health considerations for both raw and processed meats include addressing bacterial spoilage and ensuring safety. Nitrites and nitrates are widely used in the meat industry to enhance color and flavor and extend shelf life. However, health concerns linked to their use make reducing nitrites and nitrates in meat production a significant challenge with potential benefits for both the food industry and consumer health. This challenge has been addressed with the use of biopreservatives, i.e., substances extracted from natural sources or produced by fermentation that can enhance food quality and safety. In this article, we assess the use of live biopreservatives (LBs), defined here as microorganisms that produce antimicrobial substances that can be used to preserve and extend the shelf life of food. Moreover, the potential synergistic effects of LBs with bacteriophages and biodegradable food packaging for meat is also explored. This innovative combination offers a comprehensive approach to meat preservation, enhancing both microbial control and sustainability. Overall, the inclusion of LBs extends the shelf life of meat products through bacteriostatic mechanisms, whereas bacteriophages offer direct (lytic) action against pathogens. Enhancing meat preservation and safety with mixed microbe-mediated strategies requires deeper empirical and theoretical insights and further revision of laws and ethical considerations. Full article

The safety and health of food have been persistent concerns, particularly about meat products. Low-temperature meat products refer to those that are processed at lower temperatures. Meat, rich in proteins and other nutrients, is highly susceptible to microbial contamination, leading to spoilage, particularly when processed at lower temperatures that increase storage and transportation requirements. In response to the limitations of conventional preservation methods, such as heat treatment and chemical bacteriostats, emerging preservation technologies are increasingly being adopted. These technologies aim to mitigate the negative effects of microorganisms on meat products. Non-thermal technologies and biotechnological approaches, which are low in energy consumption and energy efficiency, are becoming more prevalent. Non-thermal sterilization technology is widely applied in various food products. It maintains the original quality of food, enhances food safety, reduces energy consumption, and improves production efficiency. Biocides are extensively used in the antibacterial field owing to their high efficiency, low toxicity, and long-lasting properties. Both non-thermal sterilization technology and biocides can ensure food safety, extend the shelf life of food products, improve food quality, meet consumers’ demand for natural and healthy food, enhance market competitiveness, and play a positive role in promoting the sustainable development of the food industry. This paper provides a comprehensive review of the specific applications of biocides and non-thermal sterilization methods in food, highlighting the control parameters and their effects on microbes during low-temperature meat processing, to supply pertinent researchers with theoretical references. Full article

Control of bacterial growth in food is essential to maintaining food quality and safety. The use of food additives is one answer raised to address this problem. However, some synthetic antimicrobial additives pose minor to serious health risks to consumers. Natural antimicrobial additives are potential alternatives to synthetic additives that can control microbial growth without significant health risks. This study evaluated the bacteriostatic effect of rosemary essential oil (REO) and oregano essential oil (OEO) against E. coli ATCC 9637, a non-pathogenic surrogate of Salmonella spp. in culture and in raw chicken breast. Final concentrations of 1.5% REO and 0.15% OEO were added to cultures of E. coli ATCC 9637, and the growth rate was evaluated. Raw chicken breast pieces were dipped in E. coli ATCC 9637 cultures prior to being dipped in 1.5% REO and 0.15% OEO. The chicken samples were then taken at two-day intervals, and the growth of E. coli ATCC 9637 was analyzed. No growth was observed in the cultures after a 24 h incubation period. The chicken samples treated with 1.5% REO resulted in a 0.69 log reduction compared to the positive control, while those treated with 0.15% OEO resulted in a 0.31 log reduction (p < 0.05). This shows that REO and OEO are effective against E. coli ATCC 9637 and have promise as natural antimicrobial agents. Full article

Background: The emergence of antibiotic-resistant bacteria, including Staphylococcus epidermidis, underscores the need for novel antimicrobial agents. Celastrol, a natural compound derived from the plants of the Celastraceae family, has demonstrated promising antibacterial and antibiofilm properties against various pathogens. Objectives: This study aims to evaluate the antibacterial effects, mechanism of action, and antibiofilm activity of celastrol against S. epidermidis, an emerging opportunistic pathogen. Methods: To investigate the mechanism of action of celastrol, its antibacterial activity was evaluated by determining the time–kill curves, assessing macromolecular synthesis, and analysing its impact on the stability and functionality of the bacterial cell membrane. Additionally, its effect on biofilm formation and disruption was examined. Results: Celastrol exhibited significant antibacterial activity with a minimal inhibitory concentration (MIC) of 0.31 μg/mL and minimal bactericidal concentration (MBC) of 15 μg/mL, which is superior to conventional antibiotics used as control. Time–kill assays revealed a concentration-dependent bactericidal effect, with a shift from bacteriostatic activity at lower concentrations to bactericidal and lytic effect at higher concentrations. Celastrol inhibited cell wall biosynthesis by blocking the incorporation of N-acetylglucosamine (NAG) into peptidoglycan. In contrast, the cytoplasmic membrane was only affected at higher concentrations of the compound or after prolonged exposure times. Additionally, celastrol was able to disrupt biofilm formation at concentrations of 0.9 μg/mL and to eradicate pre-formed biofilms at 7.5 μg/mL in S. epidermidis. Conclusions: Celastrol exhibits significant antibacterial and antibiofilm activities against S. epidermidis, with a primary action on cell wall synthesis. Its efficacy in disrupting the formation of biofilms and pre-formed biofilms suggests its potential as a therapeutic agent for infections caused by biofilm-forming S. epidermidis resistant to conventional treatments. Full article

Over the past decade, foodborne diseases have become a significant public health concern, affecting millions of people globally. Major pathogens like Salmonella spp., Escherichia coli, Listeria monocytogenes, and Staphylococcus aureus contaminate food and cause several infections. This study investigates the potential of thyme essential oil (Thy-EO) as a natural antimicrobial agent against most common and re-emerging foodborne bacteria, including S. enterica, Yersinia enterocolitica, and L. monocytogenes. Preliminary tests provided qualitative evidence of Thy-EO’s efficacy by evaluating its antibacterial activity through direct contact and vapor phase exposure. Then, the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were defined to quantitatively evaluate the bacteriostatic and bactericidal effects of Thy-EO, revealing a strong inhibitory effect against S. enterica, Y. enterocolitica and L. monocytogenes. Additionally, Thy-EO exerted rapid bactericidal kinetics characterized by the disruption of bacterial cell membrane integrity over time. Results highlight Thy-EO’s potential as an alternative antimicrobial agent, demonstrating that treatment with Thy-EO significantly and irreversibly affects the growth of the tested foodborne pathogens. Full article

Vibrio parahaemolyticus is a key foodborne pathogen in seafood that poses health risks to consumers. The application of phages and organic acids is considered an alternative strategy for controlling bacterial contamination in foods. In the present study, the genome features of five previously isolated virulent V. parahaemolyticus phages (VPpYZU64, VPpYZU68, VPpYZU81, VPpYZU92, and VPpYZU110) were characterized, and their bacteriostatic effects in combination with citric acid were analyzed. Genome sequencing of the five phages showed a total genome length of 76,153–144,768 bp. No virulent or drug-resistant genes were detected in the five phages. Bacterial inhibition testing of salmon fillets stored at 25 °C for 12 h showed that the number of V. parahaemolyticus decreased by 2.02 and 3.84 log CFU/g after treatment with a phage mixture, VPpMIx, and the combination of phage mixture VPpMIx and citric acid. In addition, phage VPpYZU64 combined with 600 μg/mL citric acid exhibited the highest biofilm reduction rate for V. parahaemolyticus. Collectively, our results show that combining phages and citric acid is a natural and efficient method of controlling V. parahaemolyticus growth in seafood. Full article

Mycobacterium tuberculosis (Mtb) is one of the most successful bacterial pathogens in human history. Even in the antibiotic era, Mtb is widespread and causes millions of new cases of tuberculosis each year. The ability to disrupt the host’s innate and adaptive immunity, as well as natural persistence, complicates disease control. Tuberculosis traditional therapy involves the long-term use of several antibiotics. Treatment failures are often associated with the development of resistance to one or more drugs. The development of medicines that act on new targets will expand treatment options for tuberculosis caused by multidrug-resistant or extensively drug-resistant Mtb. Therefore, the development of drugs that target virulence factors is an attractive strategy. Such medicines do not have a direct bacteriostatic or bactericidal effect, but can disarm the pathogen so that the host immune system becomes able to eliminate it. Although cell wall-associated targets are being actively studied for anti-TB drug development, other virulence factors important for adaptation and host interaction are also worth comprehensive analysis. In this review, specific Mtb virulence factors (such as secreted phosphatases, regulatory systems, and the ESX-1 secretion system) are identified as promising targets for novel anti-virulence drug development. Additionally, models for the search of virulence inhibitors are discussed, such as virtual screening in silico, in vitro enzyme inhibition assay, the use of recombinant Mtb strains with reporter constructs, phenotypic analysis using in vitro cell infection models and specific environments. Full article

The demand for functional beverages with clean labels is growing. Arthrospira platensis and fermented products offer bioactive compounds, including antimicrobials. This study aimed to produce food-grade extracts from lactic acid-fermented A. platensis and evaluate its antimicrobial activity, lipid-reducing and glucose uptake effects, and antioxidant properties. An in situ test was also conducted to assess antimicrobial activity in commercial soft drinks against Escherichia coli. Arthrospira platensis was fermented with five different QPS LAB strains: Limosilactobacillus fermentum UPCCO 1986, Companilactobacillus farciminis UPCCO 4841, Levilactobacillus brevis UPCCO 4873, Lentilactobacillus diolivorans UPCCO 5571, and Latilactobacillus curvatus UPCCO 6133, obtaining good results in aerobic and anaerobic conditions. The results have shown that the most versatile strain in fermenting biomass is L. brevis UPCCO 4873. Important in vitro antimicrobial activity was seen against Salmonella enterica, Listeria monocytogenes, Staphylococcus aureus and Escherichia coli. The extracts that exerted the highest antimicrobial activity (4841AE/AN, 5571AE, and 6133AN) were assessed for the in situ antimicrobial activity against E. coli ATCC 11229. Overall, the antimicrobial activity of the extracts was concentration-dependent, with higher concentrations exhibiting bactericidal effects and lower concentrations displaying bacteriostatic effects. Extracts from fermented A. platensis have also significantly reduced the neutral lipid reservoirs, which were not observed without fermentations. The strongest lipid-reducing effect was obtained with A. platensis fermented with Levilactobacillus brevis UPCCO 4873. This work opens the possibility of developing bioactive extracts or natural preservatives from fermented microalgae to be used in novel functional beverages. Full article

Bacterial biofilm on implants may cause inflammation, which disturbs the process of the implant’s integration with the surrounding tissues. Such problems are becoming critical for patients’ health, especially in connection with the presence of antibiotic-resistant bacterial strains. Among the existing alternatives for drug treatments are natural-based substances. This study focused on the examination of silica coatings with curcumin and thymol, which were deposited using the sol-gel method on 3D printouts made of Ti6Al4V ELI. This substrate material is commonly used in medicine. The selective laser melting technique used for the manufacturing of samples was in line with the existing procedures applied for individual orthopedic implants. The examination involved the assessment of the coatings’ morphology, chemical composition, and biological effect. The antibacterial properties were tested using a flow cytometer using Escherichia coli, and the cytotoxicity on Saos-2 cells was assessed using the LIVE/DEAD test. The obtained results showed that it is possible to produce silica sol-gel coatings with the addition of specific natural substances in concentrations assuring a bacteriostatic effect. The produced coatings did not show any cytotoxic effect, which confirms the possibility of using both curcumin and thymol as additives to coatings used in medicine, e.g., for orthopedic implants. Full article