Search Results (36)

Listeria monocytogenes poses health threats due to its resilience and potential to cause severe infections, especially in vulnerable populations. Plant extracts and/or phytocomplexes have demonstrated the capability of natural compounds in mitigating L. monocytogenes virulence. Here we explored the suitability of a computational pipeline envisioned to identify the molecular determinants for the recognition between the bacterial protein internalin A (InlA) and the human E-cadherin (Ecad), which is the first step leading to internalization. This pipeline consists of molecular docking and extended atomistic molecular dynamics simulations to identify key interaction clusters between InlA and Ecad. It exploits this information in the screening of chemical libraries of natural compounds that might competitively interact with InIA and hence impede the formation of the InIA–Ecad complex. This strategy was effective in providing a molecular model for the anti-adhesive activity of punicalagin and disclosed two natural phenolic compounds with a similar interaction pattern. Besides elucidating key aspects of the mutual recognition between InIA and Ecad, this study provides a molecular basis about the mechanistic underpinnings of the anti-adhesive action of punicalagin that enable application against L. monocytogenes. Full article

Background/Objectives: Agave amica (Medik.) Thiede & Govaerts (Asparagaceae family) is an ornamental bulbous species, widely used for its fragrance but less studied as a medicinal species. This study is aimed at assessing the phenolic profile and selected biological properties of ethanolic extracts obtained from the aerial parts and bulbs of A. amica cultivated in Romania. Methods: The phenolic composition was characterized by spectrophotometric methods and LC/MS analysis. The antioxidant activity was evaluated by DPPH (2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity) and FRAP (Ferric reducing antioxidant power) tests, while the in vitro antimicrobial capacity was investigated by the agar-well diffusion, the broth microdilution, and the antibiofilm assays. Cytotoxicity was tested on a colorectal adenocarcinoma cell line (DLD-1) by a CCK-8 assay. Results: Both ethanolic extracts showed important polyphenol content and caffeic acid as their main compound. Significantly higher amounts of total polyphenols (44.25 ± 1.08 mg/g), tannins (12.55 ± 0.34 mg/g), flavonoids (9.20 ± 0.19 mg/g), caffeic acid derivatives (19.95 ± 0.05 mg/g), and also antioxidant activity (IC₅₀ = 0.82 ± 0.02 mg/mL, and 79.75 ± 1.80 µM TE/g, respectively) were found for the aerial parts extract compared to the bulbs one (p < 0.001). Notable anti-Candida albicans activity and moderate efficacy against Listeria monocytogenes and Staphylococcus aureus were displayed by both extracts against planktonic cells and biofilm. A dose-dependent cytotoxicity towards the colorectal adenocarcinoma cell line was recorded as well. Conclusions: This study brings novelty to the scientific literature by characterizing the phenolic profile and in vitro antimicrobial, antibiofilm, antioxidant, and antiproliferative activities of the ethanolic extracts obtained from A. amica, thus highlighting this herbal species’s medicinal potential. Full article

Invasive bacterial gastrointestinal infections represent a substantial clinical burden worldwide, contributing to significant morbidity and, in severe cases, mortality. The causative bacterial agents of these infections include Shigella spp., enteroinvasive Escherichia coli, Salmonella spp., Campylobacter jejuni, Yersinia enterocolitica, and Listeria monocytogenes. Given the growing challenges of therapy failures and rising antibiotic resistance, there is still an unmet need to identify novel, effective, and safe compounds exhibiting antimicrobial, anti-inflammatory, and immunomodulatory activities. In the present review, we aimed to compile current data regarding three alkaloids—berberine, sanguinarine, and cheleritrin—which hold significant promise in treating bacterial invasive gastrointestinal diseases. Our review extended beyond the direct antimicrobial properties of these compounds against pathogens capable of breaching the intestinal epithelial barrier. We also presented their modulatory effects on intestinal barrier integrity and their influence on the composition and function of the resident gut microbiota, thereby highlighting their potential indirect role in attenuating pathogen invasion and disease progression. Thus, our review presents alkaloids as potential preparations that potentiate the activity of classic anti-infective drugs, as well as substances that, by affecting the microbiome and intestinal mucosa, could be used for inflammatory bowel diseases. Full article

Licorice roots are a rich source of bioactive compounds with multiple biological activities. The objective of this study was to evaluate the inhibitory effects of licorice root extract against a range of Listeria strains. In addition, the correlation of its phytochemical composition with antimicrobial properties was also investigated. Thus, the bacteriostatic and bactericidal effects of licorice root extract on seven Listeria monocytogenes strains, L. grayi, L. seeligeri, and L. ivanovii were determined. The minimum inhibitory and bactericidal concentrations ranged from 31.3 to 62.5 µg mL⁻¹ and from 62.5 to 250 µg mL⁻¹, respectively. The phytochemical composition of the extract was also analyzed using advanced LC-DAD- qTOF-MS; it is composed of fifty-one compounds belonging to different subgroups of flavonoids and triterpenoids. Subsequently, the anti-Listeria potency of the most abundant phytochemicals was determined using the AntiBac-Pred web tool. In silico calculation showed that liquiritin-apioside and licorice glycoside C1/C2 were strong growth inhibitors of L. monocytogenes, as their potency was comparable to well-known antibiotic substances. Overall, the present study demonstrates the potent antimicrobial effect of licorice root extract and reveals its active phytochemicals. Full article

In this study, the antimicrobial effect of Citrus limon peel extract against Listeria monocytogenes was analyzed in silico, tested in vitro, and validated in fermented cow milk during cold storage. The in silico analysis revealed that 4,5-di-O-caffeoyquinic acid interacts with L. monocytogenes proteins involved in colonization and intracellular survival. The in vitro experiments demonstrated that the anti-Listeria activity of Citrus limon peel extract is primarily attributed to limonene and phenolic compounds. In fermented milk stored at 4 °C for 7 days, the addition of Citrus limon peel extract resulted in a 2 Log reduction of L. monocytogenes compared to the control. Using the Baranyi and Roberts model, a significant decrease in the maximum growth rate (−0.021 h⁻¹) and the concentration of L. monocytogenes from 5.95 to 3.67 log CFU/mL was observed in fermented milk supplemented with a 2×MIC level of Citrus limon peel extract during storage at 4 °C. The findings from all three approaches highlighted that the inhibitory effect of Citrus limon peel extract against L. monocytogenes is primarily due to chlorogenic acid derivatives, especially 4,5-di-O-caffeoyquinic acid, and limonene. Beyond its antimicrobial properties, the supplementation of fermented milk with Citrus limon peel extract also enhances the milk antioxidant capacity and total organic acids content. Full article

The present research evaluated the effect of selected Lacticaseibacillus casei strains with anti-Listeria monocytogenes properties on the characteristics of traditional soft-ripened cheeses produced in two different seasons. Physicochemical, microbiological, texture, volatile compound, and sensory evaluations were performed on the cheeses after 60 days of ripening. The inoculation with protective cultures of selected LAB did not negatively affect the physicochemical parameters of the cheeses. Thirty-two volatile compounds were identified, including acids, alcohols, ketones, aldehydes, and esters, with differences between productions and inoculated batches. The selected LAB strains improved the sensory profile of the soft-ripened cheeses, decreasing values of texture parameters such as hardness, gumminess, and chewiness related to a softer texture and increasing umami taste and floral and lactic odor attributes. Sensory analysis revealed that consumers perceived differences between inoculated and non-inoculated cheeses, although the overall acceptability was not affected. This study provides valuable information for the artisanal cheese industry, demonstrating that it is possible to use selected protective lactic acid bacteria to assure food safety without compromising traditional flavor and even improving sensorial attributes. Full article

This study aimed at investigating the chemical composition and a selected group of bioactivities of jatoba (Hymenaea courbaril L.) pod residue. An aqueous extract (deionized water; AE) and a hydroethanolic extract (ethanol: deionized water, 70:30 v/v; ETOH) were obtained via maceration. Ten phenolic compounds were characterized via LC-DAD-ESI/MSn: seven procyanidins, two quercetin derivatives and one taxifolin derivative, with dimers and trimers of procyanidins being the main components of both extracts. Total phenolic compound levels of 2.42 ± 0.06 and 11 ± 1 mg/g were found in AE and ETOH, respectively; however, only seven compounds were identified in ETOH. The jatoba pod residue extracts showed notable antioxidant activities: ETOH had greater antioxidant potential in the OxHLIA and DPPH assays (IC₅₀ = 25.4 μg/mL and 0.71 μg/mL, respectively); however, EA demonstrated greater potential in the FRAP system (IC₅₀ = 2001.0 µM TE/mg). Only AE showed antiproliferative potential, being effective against cell lines of gastric (GI₅₀ = 35 ± 1 µg/mL) and breast (GI₅₀ = 89 ± 4 µg/mL) adenocarcinomas. Likewise, only AE showed modest anti-inflammatory potential (IC₅₀ = 225 ± 2 µg/mL) in mouse macrophages. Bacteriostatic effects against bacteria were exerted by both extracts. Enterococcus faecalis and Listeria monocytogenes (MICs = 2.5 mg/mL) were especially sensitive to the ETOH extract. Taken together, the results suggest potential for jatoba pod residue as a source of molecules with biological activities and with possible industrial applications. Full article

Recently, there has been a growing interest in reducing waste to promote environmental sustainability, with particular focus on agricultural by-products, especially fruits and vegetables. Potato, a widely used crop across various industries, generates a significant amount of peel waste. This study aims to valorize potato peels using water bath extraction (WBE) and infrared-assisted extraction (IRAE), both with distilled water as the solvent, followed by assessments of antioxidant, antibacterial, and anti-sprouting activities. Optimization using response surface methodology identified optimal extraction conditions for WBE (90 °C for 70 min) and IRAE (80 °C for 10 min), with both methods yielding 3.5 mg GAE/g DM in polyphenol content. IRAE demonstrated superior energy efficiency and enhanced antioxidant activity. The extracts exhibited antibacterial properties against both Gram-positive (Listeria monocytogenes) and Gram-negative bacteria (Proteus sp. and Salmonella sp.), with inhibition zones ranging from 10 to 14 mm. Furthermore, the potato peels extract showed significant anti-sprouting effects at room temperature, reducing both the number and size of sprouts compared with the control. HPLC analysis showed the presence of different phenolic compounds such as rutin, catechin, caffeic acid, protocatechuic acid, chlorogenic acid, p-coumaric acid, and gallic acid in one or both extracts. These findings suggest that potato peels extract holds potential for applications in the food industry as a natural preservative due to its antioxidant properties, as well as a sprout suppressant. The antibacterial activity of the extracts suggests their potential as a natural preservative as well, offering protection against both Gram-positive and Gram-negative bacteria that may be present in food. Full article

Lichens are organisms constituted by a symbiotic relationship between a fungus (mycobiont) and a photoautotrophic partner (photobiont). Lichens produce several bioactive compounds; however, the biotechnological exploitation of this organism is hampered by its slow growth. To start studying the possibility of exploiting lichens as alternative sources of bioactive compounds, eighteen lichens were collected in the north of Portugal in order to isolate and study the bioactivity of their photobionts. It was possible to isolate and cultivate only eight photobionts. Three of them, LFR1, LFA2 and LCF3, belong to the Coelastrella genus, the other two (LFA1 and LCF1) belong to the Chlorella genus and for the remaining three photobionts, LFS1, LCA1 and LCR1, it was impossible to isolate their microalgae. These only grow in consortium with bacteria and/or cyanobacteria. All extracts showed antioxidant activity, mainly at a concentration of 10 mg.mL⁻¹. LFS1, a consortium extract, showed the highest antioxidant power, as well as the highest concentration of phenolic compounds (5.16 ± 0.53 mg of gallic acid equivalents (GAE).g⁻¹). The extracts under study did not show significant antibacterial activity against Escherichia coli, Listeria or Salmonella. The Coelastrella sp. and LFA1 extracts showed the highest hyaluronidase inhibition. The LFR1 extract at a concentration of 5 mg.mL⁻¹ showed the highest anti-inflammatory activity (79.77 ± 7.66%). The extracts of Coelastrella sp. and LFA1 also showed greater antidiabetic activity, demonstrating the high inhibitory power of α-amylase and α-glucosidase. LFR1 at a concentration of 5 mg.mL⁻¹, due to its selective cytotoxicity inhibiting the growth of cancer cells (Caco-2 cells), is a promising anticancer agent. Full article

Diarrhoea remains an important public health concern, particularly in developing countries, and has become difficult to treat because of antibacterial resistance. The development of synergistic antimicrobial agents appears to be a promising alternative treatment against diarrhoeic infections. In this study, the combined effect of tetracycline together with either nitroxoline, sanguinarine, or zinc pyrithione (representing various classes of plant-based compounds) was evaluated in vitro against selected diarrhoeic bacteria (Enterococcus faecalis, Escherichia coli, Listeria monocytogenes, Shigella flexneri, Vibrio parahaemolyticus, and Yersinia enterocolitica). The chequerboard method in 96-well microtiter plates was used to determine the sum of the fractional inhibitory concentration indices (FICIs). Three independent experiments were performed per combination, each in triplicate. It was observed that the combination of tetracycline with either nitroxoline, sanguinarine, or zinc pyrithione produced synergistic effects against most of the pathogenic bacteria tested, with FICI values ranging from 0.086 to 0.5. Tetracycline–nitroxoline combinations produced the greatest synergistic action against S. flexneri at a FICI value of 0.086. The combinations of the agents tested in this study can thus be used for the development of new anti-diarrhoeic medications. However, studies focusing on their in vivo anti-diarrhoeic activity and safety are required before any consideration for utilization in human medicine. Full article

Among the foodborne illnesses, listeriosis has the third highest case mortality rate (20–30% or higher). Emerging drug-resistant strains of Listeria monocytogenes, a causative bacterium of listeriosis, exacerbate the seriousness of this public health concern. Novel anti-Listerial compounds are therefore needed to combat this challenge. In recent years, marine actinobacteria have come to be regarded as a promising source of novel antimicrobials. Hence, our aim was to provide a narrative of the available literature and discuss trends regarding bioprospecting marine actinobacteria for new anti-Listerial compounds. Four databases were searched for the review: Academic Search Ultimate, Google Scholar, ScienceDirect, and South African Thesis and Dissertations. The search was restricted to peer-reviewed full-text manuscripts that discussed marine actinobacteria as a source of antimicrobials and were written in English from 1990 to December 2023. In total, for the past three decades (1990–December 2023), only 23 compounds from marine actinobacteria have been tested for their anti-Listerial potential. Out of the 23 reported compounds, only 2-allyoxyphenol, adipostatins E–G, 4-bromophenol, and ansamycins (seco-geldanamycin B, 4.5-dihydro-17-O-demethylgeldanamycin, and seco-geldanamycin) have been found to possess anti-Listerial activity. Thus, our literature survey reveals the scarcity of published assays testing the anti-Listerial capacity of bioactive compounds sourced from marine actinobacteria during this period. Full article

During the last few decades, there has existed an increased interest in and considerable consumer preference towards using natural and safe compounds derived from medicinal plants as alternatives to synthetic preservatives to combat microbial pathogenicity. In this regard, the present study investigated the possible synergistic interactions of the anti-foodborne bacterial capacity of linalool (L), eucalyptol (E), and camphor (C). The antibacterial synergistic effect was determined against Staphylococcus aureus, Listeria monocytogenes, Salmonella enterica Typhimurium, and Escherichia coli. The optimal predicted mixture showed the highest antibacterial activity at 33.5%, 33.2%, and 33.4% of L, E, and C, respectively. Molecular docking simulations displayed that the studied monoterpenes have effective antibacterial inhibitory effects by impeding specific virulence factors such as sortase A, listeriolysin O, L, D-Transpeptidase, and polyphosphate kinase. The selected triple combination of L, E, and C was applied as a natural preservative in minced chicken breast meat. In this regard, 1 MIC (16 µg/mL), 1.5 MIC (24 µg/mL), and 2 MIC (32 µg/mL) of L. monocytogenes were used, and the microbiological, physicochemical, and sensory analyses were monitored for 14 days of storage at 4 °C. The L/E/C mixture at different levels could delay lipid and protein oxidation, inhibit the microorganisms, and maintain the sensory attributes. Additionally, by using chemometric tools, strong connections between physicochemical properties, microbiological parameters, and organoleptic attributes were established. Concisely, this research confers the importance of the use of blended monoterpenes and highlights their antibacterial mode of action, effectiveness, and synergistic effects as a powerful and safe bio-preservative formulation in chicken meat products. Full article

This study was conducted to examine the chemical composition of the essential oils (EOs) from six Tunisian Eucalyptus species and to evaluate their anti-enzymatic and antibiofilm activities. The EOs were obtained through hydro-distillation of dried leaves and subsequently analyzed using GC/MS. The main class of compounds was constituted by oxygenated monoterpenes, particularly prominent in E. brevifolia (75.7%), E. lehmannii (72.8%), and E. woollsiana (67%). Anti-enzymatic activities against cholinesterases, α-amylase, and α-glucosidase were evaluated using spectrophotometric methods. Notably, the E. brevifolia, E. extensa, E. leptophylla, E. patellaris, and E. woollsiana EOs displayed potent acetylcholinesterase (AChE) inhibition (IC₅₀: 0.25–0.60 mg/mL), with E. lehmannii exhibiting lower activity (IC₅₀: 1.2 mg/mL). E. leptophylla and E. brevifolia showed remarkable α-amylase inhibition (IC₅₀: 0.88 mg/mL), while E. brevifolia and E. leptophylla significantly hindered α-glucosidase (IC₅₀ < 30 mg/mL), distinguishing them from other EOs with limited effects. Additionally, the EOs were assessed for their anti-biofilm properties of Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative (Acinetobacter baumannii, Pseudomonas aeruginosa and Escherichia coli) bacterial strains. The E. extensa EO demonstrated the main antibiofilm effect against E. coli and L. monocytogenes with an inhibition > 80% at 10 mg/mL. These findings could represent a basis for possible further use of Eucalyptus EOs in the treatment of human microbial infections and/or as a coadjutant in preventing and treating Alzheimer’s disease and/or diabetes mellitus. Full article

Natural environments possess a reservoir of compounds exerting antimicrobial activity that are forms of defence for some organisms against others. Recently, they have become more and more attractive in the food sector due to the increasing demand for natural compounds that have the capacity to protect food from pathogenic microorganisms. Among foodborne pathogens, Listeria monocytogenes can contaminate food during production, distribution, or storage, and its presence is especially detected in fresh, raw food and ready-to-eat products. The interest in this microorganism is related to listeriosis, a severe disease with a high mortality rate that can occur after its ingestion. Starting from this premise, the present review aims to investigate plant extract and fermented plant matrices, as well as the compounds or mixtures of compounds produced during microbial fermentation processes that have anti-listeria activity. Full article

Onion skins (OS) are a by-product of onion processing that causes both biological and environmental problems. Thus, OS could be used sustainably and as means of circular economy since they contain valuable bioactive compounds that can be used for the production of high-added-value products. This study aims to evaluate the potential antioxidant, antimicrobial, and anticancer properties of onion OS crude extracts. The extracts were prepared using different solvents (i.e., water, ethanol, and their mixtures) and evaluated for their total phenolic content and phytochemical composition, their antioxidant activity (using the DPPH radical scavenging assay, the ferric reducing antioxidant power (FRAP) assay, and the hydrogen peroxide scavenging assay), anti-inflammatory properties, as well as for their antimicrobial (against Listeria monocytogenes, Escherichia coli O157:H7, Bacillus cereus, Enterococcus faecalis, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhimurium, and Yersinia enterocolitica) and anticancer (against human breast cancer cells (MCF-7) and human glioblastoma cells (U-87 MG)) activity. The results revealed that the extracts contained a significant amount of phenolic compounds, ranging between 348.71 and 795.11 mg gallic acid equivalents per g of dry weight. The extracts showed promising cytotoxic effects (up to ~40%) against cancer cell lines, indicating their potential as a natural source of anticancer agents. Additionally, the extracts exhibited strong antioxidant and antimicrobial activity against the tested microorganisms. The findings of this study suggest that OS crude extracts could be a promising candidate for developing natural functional foods and pharmaceuticals. They could be used as natural alternatives for the prevention and treatment of various diseases caused by oxidative stress, microbial infections, or cancer since they are a valuable source of bioactive compounds that can be used for various applications such as food preservation, nutraceuticals, and pharmaceuticals. Full article