Tannin-rich pomegranate rind extracts reduce adhesion to and invasion of Caco-2 Cells by Listeria monocytogenes and decrease its expression of virulence genes

The effects of pomegranate (Punica granatum) on nonalcoholic fatty liver disease: A systematic review of in vivo interventional studies

Nonalcoholic fatty liver disease (NAFLD) is a disorder in which excess fat accumulates in hepatocytes and can lead to serious complications. Oxidative stress is one of the leading causes of NAFLD. Pomegranates are considered antioxidant-rich fruit. This systematic review study was aimed to investigate the impact of pomegranate on NAFLD. PubMed, Scopus, and Google Scholar databases/search engines (from inception up to July 2023) were searched for interventional studies (human and animal) that examined the effects of supplementation with different parts of pomegranate including fruits, peels, seeds, or flower on NAFLD outcomes. A total of 222 articles were retrieved following the initial search. After excluding duplicates, the title and abstract of 114 articles were screened. Afterward, irrelevant articles were removed and the full texts of the remaining 27 articles were reviewed. Eventually, 19 articles (16 animal and three human interventional studies) that met the inclusion criteria, published between 2009 and 2023, were included in this systematic review. Our study indicates the potential beneficial effects of different parts of pomegranate on the improvement of NAFLD. However, given that the majority of the included articles were animal studies, further investigations in the form of human clinical trials are warranted to suggest a clinical indication of such interventions.

Natural Antimicrobials: A Reservoir to Contrast Listeria monocytogenes

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.

A Two Bacteriocinogenic Ligilactobacillus Strain Association Inhibits Growth, Adhesion, and Invasion of Salmonella in a Simulated Chicken Gut Environment

In this study, we aimed to develop a protective probiotic coculture to inhibit the growth of Salmonella enterica serovar Typhimurium in the simulated chicken gut environment. Bacterial strains were isolated from the digestive mucosa of broilers and screened in vitro against Salmonella Typhimurium ATCC 14028. A biocompatibility coculture test was performed, which identified two biocompatible strains, Ligilactobacillus salivarius UO.C109 and Ligilactobacillus saerimneri UO.C121 with high inhibitory activity against Salmonella. The cell-free supernatant (CFS) of the selected isolates exhibited dose-dependent effects, and the inhibitory agents were confirmed to be proteinaceous by enzymatic and thermal treatments. Proteome and genome analyses revealed the presence of known bacteriocins in the CFS of L. salivarius UO.C109, but unknown for L. saerimneri UO.C121. The addition of these selected probiotic candidates altered the bacterial community structure, increased the diversity of the chicken gut microbiota challenged with Salmonella, and significantly reduced the abundances of Enterobacteriaceae, Parasutterlla, Phascolarctobacterium, Enterococcus, and Megamonas. It also modulated microbiome production of short-chain fatty acids (SCFAs) with increased levels of acetic and propionic acids after 12 and 24 h of incubation compared to the microbiome challenged with S. Typhimurium. Furthermore, the selected probiotic candidates reduced the adhesion and invasion of Salmonella to Caco-2 cells by 37-39% and 51%, respectively, after 3 h of incubation, compared to the control. These results suggest that the developed coculture probiotic strains has protective activity and could be an effective strategy to control Salmonella infections in poultry.

Pomegranate (Punica granatum L.) peel extract ameliorates metabolic syndrome risk factors in patients with non-alcoholic fatty liver disease: a randomized double-blind clinical trial

INTRODUCTION

Non-alcoholic fatty liver disease (NAFLD) is a metabolic syndrome (MS)-related liver disorder that has an increasing prevalence. Thus, the aim of our study is to evaluate the effects of pomegranate peel extract (PP) supplementation on hepatic status and metabolic syndrome risk factors.

METHODS

In phase one, the hydro-alcoholic extraction of the peel of 750 kg of pomegranate (Punica granatum L.) was performed by the soaking method. Then, in phase two, NAFLD patients received 1500 mg of placebo (n = 37) or pomegranate peel capsules (n = 39) with a 500-kcal deficit diet for 8 weeks. Gastrointestinal intolerance, dietary intake, lipid and glycemic profiles, systolic and diastolic blood pressure, body composition, insulin resistance indexes, and elastography-evaluated NAFLD changes were followed.

RESULTS

The mean age of participants was 43.1 ± 8.6 years (51.3% female). Following the intervention, the mean body weight (mean changes: -5.10 ± 2.30 kg), waist circumference (-7.57 ± 2.97 cm), body mass index (-1.82 ± 0.85 kg/m2), body fat index (-1.49 ± 0.86), and trunk fat (- 3.93 ± 3.07%), systolic (-0.63 ± 0.29 cmHg) and diastolic (-0.39 ± 0.19 cmHg) blood pressure, total cholesterol (-10.51 ± 0.77 mg/dl), triglyceride (-16.02 ± 1.7 mg/dl), low-density lipoprotein cholesterol (-9.33 ± 6.66 mg/dl; all P < 0.001), fat free mass (- 0.92 ± 0.90 kg; P < 0.003), and fasting blood sugar (-5.28 ± 1.36 mg/dl; P = 0.02) decreased significantly in PP in contrast to the placebo group in the raw model and when adjusted for confounders. Also, high-density lipoprotein cholesterol (5.10 ± 0.36 mg/dl), liver steatosis and stiffness (- 0.30 ± 0.17 and - 0.72 ± 0.35 kPa, respectively, all P < 0.001) improved in the PP group. However, fasting insulin (P = 0.81) and homeostatic model assessment for insulin resistance (HOMA-IR) (P = 0.93) were not significantly different when comparing two groups during the study in the raw and even adjusted models.

CONCLUSION

In conclusion, 1500 mg pomegranate peel extract along with a weight-loss diet improved metabolic syndrome risk factors and reduced hepatic steatosis in patients with NAFLD after 8 weeks.

Transcriptomics of Listeria monocytogenes Treated With Olive Leaf Extract

Listeria monocytogenes is a regulated foodborne pathogen that is known to cause listeriosis, a disease associated with high mortality rates in humans. Olive leaf extract (OLE) has been shown to act as a plant antimicrobial and inhibit the growth of pathogens, such as L. monocytogenes, although its mode of action has not been defined. To help identify the cellular mechanisms important for conveying these beneficial traits, RNA-Seq was used to study the transcriptome of L. monocytogenes upon exposure to a sublethal level of OLE. Results obtained from cells cultured both with and without OLE at two different time points (3.5-h and 24-h) revealed 661 genes that were differentially expressed. Of the differentially expressed genes (DEGs) identified, transcription was altered for 171 genes in response to the 3.5-h OLE treatment while 490 genes were altered in response to the 24-h OLE treatment. These DEGs included but were not limited to genes encoding for signal transduction, ATP-binding cassette (ABC) transporters, and the phosphotransferase system. Interestingly, several virulence-related genes were downregulated including an ABC transporter permease previously shown to negatively regulate biofilm formation, genes involved in flagella assembly and binding/entry into host cells as well as those regulating acid resistance suggesting that OLE may decrease the virulence potential of L. monocytogenes. Furthermore, quantitative reverse-transcription PCR was used to validate the data obtained via RNA-Seq. Our study provides insight into the mode of action of OLE treatment against L. monocytogenes and may aid in identifying synergetic strategies to inhibit L. monocytogenes in food.

The In Vitro and In Vivo Synergistic Antimicrobial Activity Assessment of Vacuum Microwave Assisted Aqueous Extracts from Pomegranate and Avocado Fruit Peels and Avocado Seeds Based on a Mixtures Design Model

The present study aimed to assess the antimicrobial properties of encapsulated lyophilized powdered extracts of pomegranate peels (PP), avocado peels (AP) and avocado seeds (AS) in vitro and in vivo. Minimum Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) methods, optical density measurement, and well diffusion assay were used to determine antimicrobial activity against food borne bacteria (Gram− Escherichia coli, Salmonella typhimurium, Campylobacter jejuni, Pseudomonas putida), (Gram+ Staphylococcus aureus, Listeria monocytogenes, Clostridium perfringens, Lactobacillus plantarum), and fungi (Penicillium expansum and Aspergillus niger) based on a mixture design model. Additionally, the most effective powder was studied in vivo in yogurt, cream cheese, and minced meat burger. The samples that contained high polyphenol content also exhibited higher antioxidant, antimicrobial, and antifungal activity. From the results of the well diffusion, the MIC/MBC, and the cell optical density assays, the antimicrobial activity of the extracts was found to be correlated to the total phenolic content (TPC) of the samples and the type of the microorganism. The pomegranate peels extract presented the higher TPC and antioxidant activity and constitute the highest percentage in the most active antimicrobial mixture. The powders that were tested in vitro showed microbial type-dependent effects in each food model. The results presented here can be further studied in the large-scale industrial production of natural food preservatives.

Potential Role of Plant Extracts and Phytochemicals Against Foodborne Pathogens

Foodborne diseases are one of the major causes of morbidity and mortality, especially in low-income countries with poor sanitation and inadequate healthcare facilities. The foremost bacterial pathogens responsible for global outbreaks include Salmonella species, Campylobacter jejuni, Escherichia coli, Shigella sp., Vibrio, Listeria monocytogenes and Clostridium botulinum. Among the viral and parasitic pathogens, norovirus, hepatitis A virus, Giardia lamblia, Trichinella spiralis, Toxoplasma and Entamoeba histolytica are commonly associated with foodborne diseases. The toxins produced by Staphylococcus aureus, Bacillus cereus and Clostridium perfringens also cause these infections. The currently available therapies for these infections are associated with various limited efficacy, high cost and side-effects. There is an urgent need for effective alternative therapies for the prevention and treatment of foodborne diseases. Several plant extracts and phytochemicals were found to be highly effective to control the growth of these pathogens causing foodborne infections in in vitro systems. The present review attempts to provide comprehensive scientific information on major foodborne pathogens and the potential role of phytochemicals in the prevention and treatment of these infections. Further detailed studies are necessary to evaluate the activities of these extracts and phytochemicals along with their mechanism of action using in vivo models.

Food Safety through Natural Antimicrobials

Microbial pathogens are the cause of many foodborne diseases after the ingestion of contaminated food. Several preservation methods have been developed to assure microbial food safety, as well as nutritional values and sensory characteristics of food. However, the demand for natural antimicrobial agents is increasing due to consumers' concern on health issues. Moreover, the use of antibiotics is leading to multidrug resistant microorganisms reinforcing the focus of researchers and the food industry on natural antimicrobials. Natural antimicrobial compounds from plants, animals, bacteria, viruses, algae and mushrooms are covered. Finally, new perspectives from researchers in the field and the interest of the food industry in innovations are reviewed. These new approaches should be useful for controlling foodborne bacterial pathogens; furthermore, the shelf-life of food would be extended.

Inhibitory Effect of Thymoquinone on Listeria monocytogenes ATCC 19115 Biofilm Formation and Virulence Attributes Critical for Human Infection

This study aimed to determine the antimicrobial activity of thymoquinone (TQ) against Listeria monocytogenes, and to examine its inhibitory effects on biofilm formation, motility, hemolysin production, and attachment-invasion of host cells. The minimum inhibitory concentrations (MICs) of TQ against eight different L. monocytogenes strains ranged from 6.25-12.50 μg/mL. Crystal violet staining showed that TQ clearly reduced biofilm biomass at sub-MICs in a dose-dependent manner. Scanning electron microscopy suggested that TQ inhibited biofilm formation on glass slides and induced an apparent collapse of biofilm architecture. At sub-MICs, TQ effectively inhibited the motility of L. monocytogenes ATCC 19115, and significantly impacted adhesion to and invasion of human colon adenocarcinoma cells as well as the secretion of listeriolysin O. Supporting these findings, real-time quantitative polymerase chain reaction analysis revealed that TQ down-regulated the transcription of genes associated with motility, biofilm formation, hemolysin secretion, and attachment-invasion in host cells. Overall, these findings confirm that TQ has the potential to be used to combat L. monocytogenes infection.

Thymoquinone Inhibits Biofilm Formation and Attachment-Invasion in Host Cells of Vibrio parahaemolyticus

Vibrio parahaemolyticus is a halophilic Gram-negative foodborne pathogen that is widely distributed in marine environments. It can cause acute gastroenteritis and other diseases. This study aimed to investigate the antivirulence activity of thymoquinone (TQ) on V. parahaemolyticus. TQ was shown to effectively inhibit V. parahaemolyticus. Subminimum inhibitory concentrations of TQ inhibited swimming and swarming motility, quorum sensing, biofilm formation, the ability of V. parahaemolyticus to adhere and invade the host cells, and the expression of virulence-associated genes of V. parahaemolyticus. These findings suggest that TQ can effectively inhibit the growth of V. parahaemolyticus and significantly reduce its pathogenicity. Considering its safety and various biological activities, TQ has the potential to be developed as a natural antibacterial substance to reduce the diseases associated with V. parahaemolyticus.

The in vitro and in vivo protective effects of tannin derivatives against Salmonella enterica serovar Typhimurium infection

In this study, we investigated the protective effects of tannin-derived components, gallic acid (GA) and tannic acid (TA), in vitro and in vivo against Salmonella infection in mice. Both GA and TA showed antibacterial effects against Salmonella (S.) Typhimurium as well as inhibitory effects on the adherence, invasion, and intracellular growth of the pathogens in macrophages. Following a lethal dose of Salmonella infection in mice, reduced virulence in both GA- and TA-treated groups was observed based on reduced mortality rates. In the non-infected groups, the average weights of the spleens and livers of GA- or TA-treated mice were not significantly different with the control group. In addition, the average weights of these organs in all of the Salmonella-infected groups were not significantly different but the numbers of bacteria in the spleens and livers in both GA- and TA-treated mice were significantly reduced. The levels of cytokine production in non-infected mice revealed that GA-treated and TA-treated mice elicited an increased level of IFN-γ, and both IFN-γ and MCP-1, respectively, as compared with the PBS-treated group. These findings highlight the potential of GA and TA as alternatives for the treatment of salmonellosis and as supplements to conventional antimicrobial food additives.