Aptamer-drug conjugates-loaded bacteria for pancreatic cancer synergistic therapy.

Pancreatic cancer is one of the most malignant tumors with the highest mortality rates, and it currently lacks effective drugs. Aptamer-drug conjugates (ApDC), as a form of nucleic acid drug, show great potential in cancer therapy. However, the instability of nucleic acid-based drugs in vivo and the avascularity of pancreatic cancer with dense stroma have limited their application. Fortunately, VNP20009, a genetically modified strain of Salmonella typhimurium, which has a preference for anaerobic environments, but is toxic and lacks specificity, can potentially serve as a delivery vehicle for ApDC. Here, we propose a synergistic therapy approach that combines the penetrative capability of bacteria with the targeting and toxic effects of ApDC by conjugating ApDC to VNP20009 through straightforward, one-step click chemistry. With this strategy, bacteria specifically target pancreatic cancer through anaerobic chemotaxis and subsequently adhere to tumor cells driven by the aptamer's specific binding. Results indicate that this method prolongs the serum stability of ApDC up to 48 h and resulted in increased drug concentration at tumor sites compared to the free drugs group. Moreover, the aptamer's targeted binding to cancer cells tripled bacterial colonization at the tumor site, leading to increased death of tumor cells and T cell infiltration. Notably, by integrating chemotherapy and immunotherapy, the effectiveness of the treatment is significantly enhanced, showing consistent results across various animal models. Overall, this strategy takes advantage of bacteria and ApDC and thus presents an effective synergistic strategy for pancreatic cancer treatment.

Assessment of receptor-mediated activity (AhR and ERα), mutagenicity, and teratogenicity of metal shredder wastes in Wallonia, Belgium.

In this study, hazardous wastes including fluff, dust, and scrubbing sludge were sampled in 2019 from two metal shredding facilities located in Wallonia, Belgium. To assess the extent of the contamination, a global approach combining chemical and biological techniques was used, to better reflect the risks to health and the environment. The samples investigated induced significant in vitro aryl hydrocarbon receptor (AhR) agonistic bioactivities and estrogenic receptor (ERα) (ant)agonistic bioactivities in the respective CALUX (chemical activated luciferase gene expression) bioassays. The mutagenicity of the samples was investigated with the bacterial reverse gene mutation test using the Salmonella typhimurium TA98 and TA100 strains. Except for the sludge sample (site 3), all samples induced a mutagenic response in the TA98 strain (± S9 metabolic fraction) whereas in the TA100 strain (+ S9 metabolic fraction), only the sludge sample (site 2) showed a clear mutagenic effect. The in vivo toxicity/teratogenicity of the shredder wastes was further evaluated with zebrafish embryos. Except for the dust sample (site 2), all samples were found to be teratogenic as they returned teratogenic indexes (TIs) > 1. The high levels of contamination, the mutagenicity, and the teratogenicity of these shredder wastes raise significant concerns about their potential negative impacts on both human health and environment.

Toxicological profiling of methanolic seed extract of Abutilon indicum (L.) Sweet: in-vitro and in-vivo analysis.

ETHNOPHARMACOLOGICAL RELEVANCE: Abutilon indicum, a shrub of the Malvaceae family, is found abundantly in tropical countries like India. A. indicum is widely used for its high medicinal properties. Traditionally, A. indicum seed powder is consumed to treat piles, constipation, chronic cystitis, gonorrhea, gleet, and pregnancy-related problems. Despite having numerous medicinal properties and widespread traditional use of A. indicum seeds, scientific validation, and toxicity studies have yet to be documented. AIMS OF THE STUDY: The primary objective of this study is to conduct a comprehensive study on phytochemical profiling, in-vitro cytotoxicity, mutagenicity, and in-vivo acute and sub-acute toxicity, and genotoxicity on animal models of methanolic extract of A. indicum seed (MAS). MATERIALS AND METHODS: The qualitative analysis of MAS was explored through FTIR and HR LC-MS. For in-vitro cytotoxicity, the HEK-293 cell line was used, and the TA100 (Staphylococcus typhimurium) bacterial strain was used for the Ames mutagenicity test. A single oral dose of 250, 500, 1000, or 2000 mg/kg body weight of MAS was given to each male and female rat for acute toxicity study and observed for 14 days for any toxicity signs. In the sub-acute toxicity study, 250, 500, or 1000 mg/kg body weight of MAS was administered orally to each rat for 28 days. The experimental animals were weighed weekly, and general behavior was monitored regularly. After 28 days of the experiment, the rats were sacrificed, and different serum biochemical, hematological, and histological analyses were performed. The blood samples of different doses of MAS were used for genotoxicity study through comet assay. RESULTS: FTIR analysis found different functional groups, which indicated the presence of phenolics, flavonoids, and alkaloids. HR LC-MS analysis depicts several components with different biological functions. The cell cytotoxicity and Ames mutagenicity results showed minimal toxicity and mutagenicity up to a certain dose. The acute toxicity study conducted in Wistar albino rats demonstrated zero mortality among the animals, and the LD50 value for seed extract was determined to be 2000 mg/kg body weight. Sub-acute toxicity assessments indicated that the administration of seed extract resulted in no adverse effects at dosages of 250 and 500 mg/kg body weight. However, at higher doses, specifically 1000 mg/kg body weight, the liver of the experimental rats exhibited some toxic effects. In the genotoxicity study, minimal DNA damage was found in 250 and 500 mg/kg doses, respectively, but slightly greater DNA damage was found in 1000 mg/kg doses in both male and female rats. CONCLUSIONS: The consumption of A. indicum seed powder is deemed safe; however, doses exceeding 500 mg/kg body weight may raise concerns regarding use. These findings pave the path for the creation of innovative medicines with improved efficacy and safety profiles.

Reprogramming the tumor immune microenvironment using engineered dual-drug loaded Salmonella.

Synergistic combinations of immunotherapeutic agents can improve the performance of anti-cancer therapies but may lead to immune-mediated adverse effects. These side-effects can be overcome by using a tumor-specific delivery system. Here, we report a method of targeted immunotherapy using an attenuated Salmonella typhimurium (SAM-FC) engineered to release dual payloads: cytolysin A (ClyA), a cytolytic anti-cancer agent, and Vibrio vulnificus flagellin B (FlaB), a potent inducer of anti-tumor innate immunity. Localized secretion of ClyA from SAM-FC induces immunogenic cancer cell death and promotes release of tumor-specific antigens and damage-associated molecular patterns, which establish long-term antitumor memory. Localized secretion of FlaB promotes phenotypic and functional remodeling of intratumoral macrophages that markedly inhibits tumor metastasis in mice bearing tumors of mouse and human origin. Both primary and metastatic tumors from bacteria-treated female mice are characterized by massive infiltration of anti-tumorigenic innate immune cells and activated tumor-specific effector/memory T cells; however, the percentage of immunosuppressive cells is low. Here, we show that SAM-FC induces functional reprogramming of the tumor immune microenvironment by activating both the innate and adaptive arms of the immune system and can be used for targeted delivery of multiple immunotherapeutic payloads for the establishment of potent and long-lasting antitumor immunity.

Antibacterial mode of action of garviecin LG34 against Gram-negative bacterium Salmonella typhimurium.

Garviecin LG34 produced by Lactococcus garvieae LG34 exhibits wide-spectrum antibacterial activity against both Gram-positive and Gram-negative bacteria. This work aimed at clarifying the antibacterial mode of action of garviecin LG34 against Gram-negative bacterium Salmonella typhimurium. To determine the concentration for the bacteriocin antimicrobial mode experiments, the minimum inhibitory concentration of garviecin LG34 against S. typhimurium CICC21484 was determined as 0.25 mg/ml. Garviecin LG34 decreased the viable count of S. typhimurium CICC21484 and its antibacterial activity was the dose and time dependant. Garviecin LG34 led to the dissipation of transmembrane potential, the rise in the extracellular conductivity, UV-absorbing material at 260 nm, and LDH level of S. typhimurium CICC21484. Scanning electron micrographs results shown that garviecin LG34 cause dramatic deformation and fragmentation including the flagellum shedding, pores formation in surface, and even completely breakage of S. typhimurium cell. Moreover, garviecin LG34 decreased the intracellular ATP level. The results of this study demonstrated that garviecin LG34 can destroy cell structure, increase membrane permeability of S. typhimurium, thereby might be used as biopreservative for treating food borne and salmonellosis resulting from Gram-negative bacterium S. typhimurium.

Antibacterial Effect of Euryale ferox Seed Shell Polyphenol Extract on Salmonella Typhimurium.

This study aimed to evaluate the effects of Euryale ferox Seed Shell Polyphenol Extract (EFSSPE) on a foodborne pathogenic bacterium. EFSSPE showed antimicrobial activity toward Salmonella Typhimurium CICC 22956; the minimum inhibitory concentration of EFSSPE was 1.25 mg/mL, the inhibition curve also reflected the inhibitory effect of EFSSPE on the growth of S. Typhimurium. Detection of alkaline phosphatase outside the cell revealed that EFSSPE treatment damaged the cell wall integrity of S. Typhimurium. EFSSPE also altered the membrane integrity, thereby causing leaching of 260-nm-absorbing material (bacterial proteins and DNA). Moreover, the activities of succinate dehydrogenase and malate dehydrogenase were inhibited by EFSSPE. The hydrophobicity and clustering ability of cells were affected by EFSSPE. Scanning electron microscopy showed that EFSSPE treatment damaged the morphology of the tested bacteria. These results indicate that EFSSPE can destroy the cell wall integrity and alter the permeability of the cell membrane of S. Typhimurium.

Identification of kinase inhibitors as potential host-directed therapies for intracellular bacteria.

The emergence of antimicrobial resistance has created an urgent need for alternative treatments against bacterial pathogens. Here, we investigated kinase inhibitors as potential host-directed therapies (HDTs) against intracellular bacteria, specifically Salmonella Typhimurium (Stm) and Mycobacterium tuberculosis (Mtb). We screened 827 ATP-competitive kinase inhibitors with known target profiles from two Published Kinase Inhibitor Sets (PKIS1 and PKIS2) using intracellular infection models for Stm and Mtb, based on human cell lines and primary macrophages. Additionally, the in vivo safety and efficacy of the compounds were assessed using zebrafish embryo infection models. Our screen identified 11 hit compounds for Stm and 17 hit compounds for Mtb that were effective against intracellular bacteria and non-toxic for host cells. Further experiments were conducted to prioritize Stm hit compounds that were able to clear the intracellular infection in primary human macrophages. From these, two structurally related Stm hit compounds, GSK1379738A and GSK1379760A, exhibited significant activity against Stm in infected zebrafish embryos. In addition, we identified compounds that were active against intracellular Mtb, including morpholino-imidazo/triazolo-pyrimidinones that target PIK3CB, as well as 2-aminobenzimidazoles targeting ABL1. Overall, this study provided insights into kinase targets acting at the host-pathogen interface and identified several kinase inhibitors as potential HDTs.

Evaluation of the protective properties and genotoxic potential of pyrazolo pyridine derivatives against neutron and gamma radiation using the Ames/Salmonella test system.

PURPOSE: Nuclear applications are being increasingly used in various fields, necessitating studies to protect from radiation hazards and their effects. In this study, five different chemical structures of pyrazolo [3,4-b] pyridine derivatives were synthesized. The gamma and neutron radiation protective abilities of these samples were determined and demonstrated their potential use as ingredients in radioprotective drugs. MATERIAL AND METHODS: Gamma radiation absorption parameters were calculated both theoretical and experimental. Important attenuation parameters for fast neutrons (4.5 MeV energy radiation) were figured out using the Monte Carlo simulation Geant4 code. Additionally, experimental dose rates were measured for each sample and compared to those of Paraffin and high-density polyethylene, an organic substance. Besides, Ames/Salmonella test system was aimed to detecting genotoxicity features of pyrazolo pyridine derivatives. RESULTS: All results demonstrated that each sample possesses both gamma and neutron radiation attenuation capabilities. It was determined that sample PPC4 (C20H14BrN5) exhibited the highest gamma radiation attenuation capacity among all samples, while sample PPC2 (C22H20N6) displayed an excellent neutron stopping capacity. The genotoxic properties of pyrazolo[3,4-b] pyridine derivatives were examined using the Ames/Salmonella test, and as a result, it was determined that these substances did not exhibit genotoxic effects at test doses up to 5 mM. CONCLUSION: All obtained results indicate that all PPC (pyrazolo[3,4-b] pyridine derivatives) samples do not possess a toxic effect, and they can be utilized as an active substance for the development of a drug or cream with protective properties against both gamma and neutron radiations.

Nanocoated bacteria with H2S generation-triggered self-amplified photothermal and photodynamic effect for breast cancer therapy.

Phototherapy utilizing bacterial carriers has demonstrated efficacy in anti-tumor therapy, while the poor delivery of phototherapeutic agents and immunogenicity of microbial substances remain problematic. Herein, we develop a nanocoated bacterial delivery system (IF-S.T) that in situ forms the efficient photothermal agents via biomineralization and improves the intracellular oxygenation, thus triggering the self-enhanced photothermal therapy (PTT) and photodynamic therapy (PDT) on tumor. We densely coat self-assembled IF (ICG-Fe2+) nanocomplex onto the surface of LT2, weakly virulent strain of Salmonella typhimurium (S.T), by bioadaptive nanocoating techniques, masking bacterial virulence factors and reducing the potential immune adverse effects. Upon penetrating into the tumor environment, IF-S.T responds to H2O2 to trigger the removal of the IF coating, where S.T produces excess hydrogen sulfide (H2S). H2S reacts with Fe2+, yielding ferrous sulfide (FeS) for PTT, and inhibits mitochondrial respiration to enhance tumor cell oxygenation for PDT. Consequently, IF-S.T plus laser irradiation exhibits direct tumor cells killing and elicits robust antitumor immune responses, leading to the complete tumor elimination. Thus, IF-S.T represents a promising platform for effective tumor delivery of photoactive agents for improved PTT/PDT efficacy.

A Novel Dry-Cured Ham Broth-Derived Peptide JHBp2 Effectively Inhibits Salmonella typhimurium In Vitro: Integrated Metabolomic, Proteomic, and Molecular Simulation Analyses.

JHBp2 is a peptide purified from Jinhua ham broth with antibacterial activity against Salmonella typhimurium. Untargeted metabolomics and label-free quantitative proteomics were used to analyze metabolic and protein expression changes in S. typhimurium after JHBp2 treatment. Cell wall and membrane damage results indicate that JHBp2 has membrane-disruptive properties, causing leakage of intracellular nucleic acids and proteins. Metabolomics revealed 516 differentially expressed metabolites, involving cofactor biosynthesis, purine metabolism, ABC transporters, glutathione metabolism, pyrimidine metabolism, etc. Proteomics detected 735 differentially expressed proteins, involving pyruvate metabolism, amino acid biosynthesis, purine metabolism, carbon metabolism, glycolysis/gluconeogenesis, etc. RT-qPCR and proteomics results showed a positive correlation, and molecular docking demonstrated stable binding of JHBp2 to some differentially expressed proteins. In summary, JHBp2 could disrupt the S. typhimurium cell wall and membrane structure, interfere with synthesis of membrane-related proteins, trigger intracellular substance leak, and reduce levels of enzymes and metabolites involved in energy metabolism, amino acid anabolism, and nucleotide anabolism.

Vanilla from Brazilian Atlantic Forest: In vitro and in silico toxicity assessment and high-resolution metabolomic analysis of Vanilla spp. ethanolic extracts.

The natural vanilla market, which generates millions annually, is predominantly dependent on Vanilla planifolia, a species characterized by low genetic variability and susceptibility to pathogens. There is an increasing demand for natural vanilla, prized for its complex, authentic, and superior quality compared to artificial counterparts. Therefore, there is a necessity for innovative production alternatives to ensure a consistent and stable supply of vanilla flavors. In this context, vanilla crop wild relatives (WRs) emerge as promising natural sources of the spice. However, these novel species must undergo toxicity assessments to evaluate potential risks and ensure safety for consumption. This study aimed to assess the non-mutagenic and non-carcinogenic properties of ethanolic extracts from V. bahiana, V. chamissonis, V. cribbiana, and V. planifolia through integrated metabolomic profiling, in vitro toxicity assays, and in silico analyses. The integrated approach of metabolomics, in vitro assays, and in silico analyses has highlighted the need for further safety assessments of Vanilla cribbiana ethanolic extract. While the extracts of V. bahiana, V. chamissonis, and V. planifolia generally demonstrated non-mutagenic properties in the Ames assay, V. cribbiana exhibited mutagenicity at high concentrations (5000 µg/plate) in the TA98 strain without metabolic activation. This finding, coupled with the dose-dependent cytotoxicity observed in WST-1 (Water Soluble Tetrazolium) assays, a colorimetric method that assesses the viability of cells exposed to a test substance, underscores the importance of concentration in the safety evaluation of these extracts. Kaempferol and pyrogallol, identified with higher intensity in V. cribbiana, are potential candidates for in vitro mutagenicity. Although the results are not conclusive, they suggest the safety of these extracts at low concentrations. This study emphasizes the value of an integrated approach in providing a nuanced understanding of the safety profiles of natural products, advocating for cautious use and further research into V. cribbiana mutagenicity.

Influence of administration timing of San-Huang-Xie-Xin-Tang treatment on attenuating Salmonella enterica serovar Typhimurium infection.

Salmonella infections are a serious global health concern, particularly in developing countries, and are further exacerbated by the emergence of antibiotic resistance. San-Huang-Xie-Xin-Tang (SHXXT), a traditional herbal medicine with potent anti-inflammatory properties, has recently gained attention as an alternative treatment. Our study emphasizes on the importance of precise timing in accordance with traditional Chinese medicine principles. A mouse infection model was established while different administration times of SHXXT were recorded for the body weight, clinical scores, bacterial counts in blood, and organs. Additionally, cytokine levels, fatty acids, and amino acids in the serum were also monitored. We found that administering SHXXT 1 day after Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) infection (T1 group) leads to positive outcomes. This includes restoration of body weight, improved clinical scores, and reduced bacterial counts in blood and vital organs. Interferon-gamma levels remained consistently high across all treatment groups 6 days post-infection. However, the T1 group showed exclusive suppression of serum levels of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1ß). The timing of administration significantly influenced serum fatty acid concentrations, countering Salmonella-induced disruptions, aligning with TNF-α and IL-1ß levels. SHXXT had also restored amino acid profiles disrupted by the infection, with notable effects when administered at the correct timing. Our research highlights SHXXT's potential in treating S. Typhimurium infection, emphasizing the importance of precise timing in line with traditional Chinese medicine principles for effective treatment at different disease stages.

Salmonella Typhimurium employs spermidine to exert protection against ROS-mediated cytotoxicity and rewires host polyamine metabolism to ameliorate its survival in macrophages.

Salmonella infection entails a cascade of attacks and defence measures. After breaching the intestinal epithelial barrier, Salmonella is phagocytosed by macrophages, where the bacteria encounter multiple stresses, to which it employs relevant countermeasures. Our study shows that, in Salmonella, the polyamine spermidine activates a stress response mechanism by regulating critical antioxidant genes. Salmonella Typhimurium mutants for spermidine transport and synthesis cannot mount an antioxidative response, resulting in high intracellular ROS levels. These mutants are also compromised in their ability to be phagocytosed by macrophages. Furthermore, it regulates a novel enzyme in Salmonella, Glutathionyl-spermidine synthetase (GspSA), which prevents the oxidation of proteins in E. coli. Moreover, the spermidine mutants and the GspSA mutant show significantly reduced survival in the presence of hydrogen peroxide in vitro and reduced organ burden in the mouse model of Salmonella infection. Conversely, in macrophages isolated from gp91phox-/- mice, we observed a rescue in the attenuated fold proliferation previously observed upon infection. We found that Salmonella upregulates polyamine biosynthesis in the host through its effectors from SPI-1 and SPI-2, which addresses the attenuated proliferation observed in spermidine transport mutants. Thus, inhibition of this pathway in the host abrogates the proliferation of Salmonella Typhimurium in macrophages. From a therapeutic perspective, inhibiting host polyamine biosynthesis using an FDA-approved chemopreventive drug, D, L-α-difluoromethylornithine (DFMO), reduces Salmonella colonisation and tissue damage in the mouse model of infection while enhancing the survival of infected mice. Therefore, our work provides a mechanistic insight into the critical role of spermidine in stress resistance of Salmonella. It also reveals a bacterial strategy in modulating host metabolism to promote their intracellular survival and shows the potential of DFMO to curb Salmonella infection.

Within-laboratory reproducibility of Ames test results: Are repeat tests necessary?

The Ames test is required by regulatory agencies worldwide for assessing the mutagenic and carcinogenic potential of chemical compounds. This test uses several strains of bacteria to evaluate mutation induction: positive results in the assay are predictive of rodent carcinogenicity. As an initial step to understanding how well the assay may detect mutagens present as constituents of complex mixtures such as botanical extracts, a cross-sector working group examined the within-laboratory reproducibility of the Ames test using the extensive, publicly available National Toxicology Program (NTP) Ames test database comprising more than 3000 distinct test articles, most of which are individual chemicals. This study focused primarily on NTP tests conducted using the standard Organization for Economic Co-operation and Development Test Guideline 471 preincubation test protocol with 10% rat liver S9 for metabolic activation, although 30% rat S9 and 10 and 30% hamster liver S9 were also evaluated. The reproducibility of initial negative responses in all strains with and without 10% S9, was quite high, ranging from 95% to 99% with few exceptions. The within-laboratory reproducibility of initial positive responses for strains TA98 and TA100 with and without 10% rat liver S9 was ≥90%. Similar results were seen with hamster S9. As expected, the reproducibility of initial equivocal responses was lower, <50%. These results will provide context for determining the optimal design of recommended test protocols for use in screening both individual chemicals and complex mixtures, including botanicals.

Antimicrobial effects of laurel extract, laurel essential oil, zahter extract, and zahter essential oil on chicken wings contaminated with Salmonella Typhimurium.

BACKGROUND: This study aimed to evaluate the antimicrobial effects of zahter extract, zahter essential oil, laurel extract, and laurel essential oil on Salmonella Typhimurium inoculated on chicken wings. METHODS: A total of 10 groups, including eight study groups and two control groups were formed, consisting of zahter extract and zahter essential oil and laurel extract and laurel essential oil in different proportions. In the study, laurel extract at 6.4% and 12.8% concentrations, laurel essential oil at 0.2% and 0.4% concentrations, zahter extract at 0.2% and 0.4% concentrations, and zahter essential oil at 0.2% and 0.4% concentrations were used. RESULTS: The broth microdilution method was used to evaluate the antimicrobial activity of the extract and essential oils on the S. Typhimurium. Minimum inhibitory concentrations of the extracts and essential oils used in the study against S. Typhimurium were determined. The highest inhibitory effect on S. Typhimurium was observed in the 0.4% laurel essential oil group. It was determined that the inhibitory effect increased as the concentration of laurel essential oil increased. In addition, the antimicrobial activity of zahter essential oil is less inhibitory than the laurel extract, laurel essential oil, and zahter extract. CONCLUSION: According to the results of this study, it has been revealed that extracts and essential oils obtained from zahter and laurel plants, which have been shown to be natural antimicrobial, can be used in foods as an alternative to chemical additives. To develop research results, the applicability of these extracts and essential oils in different foodstuffs should be examined using different ingredients and concentrations.

Use of organic acids to reduce Salmonella Typhimurium excretion in swine / Uso de ácidos orgânicos para reduzir a excreção de Salmonella Typhimurium em suínos

The use of antimicrobials as growth promoters and disease prevention is being constantly reduced in several animal production systems, including in the swine industry. Therefore, this study aimed to evaluate the effectiveness of using acidifiers to control Salmonella Typhimurium in 65-day-old pigs by detecting the pathogen in organs at euthanasia. For this, 24 piglets were divided into two experimental groups consisting of 12 piglets each. An untreated control group (G1) and a treatment group (G2) received a liquid organic acidifier in the drinking water for 10 days (D-5 to D5). Five days after the start of treatment (D0), all piglets were challenged with 106 CFU of Salmonella Typhimurium and assessed for 12 days (D12). Every three days (D3, D6, D9, and D12), three animals from each experimental group were euthanized and then submitted for necropsy. Samples from the intestines (ileum, cecum, mesenteric lymph nodes, and ileocolic lymph nodes), liver, spleen, and lungs were collected to isolate Salmonella. The results show that, numerically, Salmonella isolation in the organs of G2 was lower than in G1 and that the number of positive cecum samples in G1 (66.7%; 8/12) was statistically different from the number of positive models in G2 (16.7%; 2/12), with a reduction of 28.6% of the total cecum positive samples in the treated group compared to the control. Therefore, it was observed that the liquid organic acidifier product could reduce the colonization of organs by Salmonella Typhimurium. (AU)

Use of organic acids to reduce Salmonella Typhimurium excretion in swine / Uso de ácidos orgânicos para reduzir a excreção de Salmonella Typhimurium em suínos

The use of antimicrobials as growth promoters and disease prevention is being constantly reduced in several animal production systems, including in the swine industry. Therefore, this study aimed to evaluate the effectiveness of using acidifiers to control Salmonella Typhimurium in 65-day-old pigs by detecting the pathogen in organs at euthanasia. For this, 24 piglets were divided into two experimental groups consisting of 12 piglets each. An untreated control group (G1) and a treatment group (G2) received a liquid organic acidifier in the drinking water for 10 days (D-5 to D5). Five days after the start of treatment (D0), all piglets were challenged with 106 CFU of Salmonella Typhimurium and assessed for 12 days (D12). Every three days (D3, D6, D9, and D12), three animals from each experimental group were euthanized and then submitted for necropsy. Samples from the intestines (ileum, cecum, mesenteric lymph nodes, and ileocolic lymph nodes), liver, spleen, and lungs were collected to isolate Salmonella. The results show that, numerically, Salmonellaisolation in the organs of G2 was lower than in G1 and that the number of positive cecum samples in G1 (66.7%; 8/12) was statistically different from the number of positive models in G2 (16.7%; 2/12), with a reduction of 28.6% of the total cecum positive samples in the treated group compared to the control. Therefore, it was observed that the liquid organic acidifier product could reduce the colonization of organs by Salmonella Typhimurium.(AU)

O uso de antimicrobianos como promotores de crescimento e prevenção de doenças vem sendo constantemente reduzido em diversos sistemas de produção animal, inclusive na suinocultura. Portanto, o objetivo do presente estudo foi avaliar a eficácia do uso de acidificantes no controle de Salmonella Typhimurium em suínos de 65 dias de idade, detectando o patógeno em órgãos após a eutanásia. Para isso, 24 leitões foram divididos em dois grupos experimentais constituídos por 12 leitões cada. Um grupo controle não tratado (G1) e um grupo de tratamento (G2) que recebeu um acidificante orgânico líquido na água de beber por 10 dias (D-5 a D5). Cinco dias após o início do tratamento (D0), todos os animais foram inoculados oralmente com 106 UFC de Salmonella Typhimurium e avaliados por 12 dias (D12). A cada três dias (D3, D6, D9 e D12), três leitões de cada grupo experimental foram eutanasiados e posteriormente submetidos à necropsia. Amostras de intestino (íleo, ceco, linfonodos mesentéricos e linfonodos ileocólicos), fígado, baço e pulmões foram coletadas para o isolamento de Salmonella. Os resultados mostram que, numericamente, o isolamento de Salmonella nos órgãos do G2 foi inferior ao G1, e que o número de amostras positivas de ceco no G1 (66,7%; 8/12) foi estatisticamente diferente do número de amostras positivas no G2 (16,7%; 2/12), com redução de 28,6% do total de amostras positivas de ceco no grupo tratado em relação ao controle. Portanto, observou-se que o ácido orgânico líquido foi capaz de reduzir a colonização de órgãos por Salmonella Typhimurium.(AU)

Cyclopropane Fatty Acids Are Important for Salmonella enterica Serovar Typhimurium Virulence.

A variety of eubacteria, plants, and protozoa can modify membrane lipids by cyclopropanation, which is reported to modulate membrane permeability and fluidity. The ability to cyclopropanate membrane lipids has been associated with resistance to oxidative stress in Mycobacterium tuberculosis, organic solvent stress in Escherichia coli, and acid stress in E. coli and Salmonella. In bacteria, the cfa gene encoding cyclopropane fatty acid (CFA) synthase is induced during the stationary phase of growth. In the present study, we constructed a cfa mutant of Salmonella enterica serovar Typhimurium 14028s (S. Typhimurium) and determined the contribution of CFA-modified lipids to stress resistance and virulence in mice. Cyclopropane fatty acid content was quantified in wild-type and cfa mutant S. Typhimurium. CFA levels in the cfa mutant were greatly reduced compared to CFA levels in the wild type, indicating that CFA synthase is the major enzyme responsible for cyclopropane modification of lipids in Salmonella. S. Typhimurium cfa mutants were more sensitive to extreme acid pH, the protonophore CCCP, and hydrogen peroxide compared to the wild type. In addition, cfa mutants exhibited reduced viability in murine macrophages and could be rescued by the addition of the NADPH phagocyte oxidase inhibitor diphenyleneiodonium (DPI) chloride. S. Typhimurium lacking cfa was also attenuated for virulence in mice. These observations indicate that CFA modification of lipids makes an important contribution to Salmonella virulence.

Evaluation of toxicological aspects of three new benzoxazole compounds with sunscreen photophysical properties using in silico and in vitro methods.

Sunscreening chemicals protect against damage caused by sunlight most absorbing UVA or UVB radiations. In this sense, 2-(2'-hydroxyphenyl)benzoxazole derivatives with amino substituents in the 4' and 5' positions have an outstandingly high Sun Protection Factor and adequate photostability, but their toxicity is not yet known. This study aimed to evaluate the toxicity of three synthetic 2-(2'-hydroxyphenyl)benzoxazole derivatives for their possible application as sunscreens. In silico tools were used in order to assess potential risks regarding mutagenic, carcinogenic, and skin sensitizing potential. Bioassays were performed in L929 cells to assess cytotoxicity in MTT assay and genotoxic activities in the Comet assay and micronucleus test. Also, the Salmonella/microsome assay was performed to evaluate gene mutations. The in silico predictions indicate a low risk of mutagenicity and carcinogenicity of the compounds while the skin sensitizing potential was low or inconclusive. The 2-(4'-amino-2'-hydroxyphenyl)benzoxazol compound was the most cytotoxic and genotoxic among the compounds evaluated in L929 cells, but none induced mutations in the Salmonella/microsome assay. The amino substituted at the 4' position of the phenyl ring appears to have greater toxicological risks than substituents at the 5' position of 2-(phenyl)benzoxazole. The findings warrant further studies of these compounds in cosmetic formulations.

Protein extract of Bromelia karatas L. rich in cysteine proteases (ananain- and bromelain-like) has antibacterial activity against foodborne pathogens Listeria monocytogenes and Salmonella Typhimurium.

Bromelia karatas L. is a plant species from the Americas. The presence of proteases in fruits of B. karatas has been reported but scarcely studied in detail. Proteolytic enzymes from Ananas comosus have displayed antifungal and antibacterial activity. Thus, novel proteases present in B. karatas may be useful as a source of compounds against microorganisms in medicine and food production. In this work, the protein extract from the fruits of B. karatas was characterized and its antibacterial activity against Salmonella Typhimurium and Listeria monocytogenes was determined for the first time. Proteins highly similar to ananain and the fruit bromelain from A. comosus were identified as the main proteases in B. karatas fruits using liquid chromatography with tandem mass spectrometry (LC-MS/MS). The soluble protein extract (SPE) at a concentration of 2.0 mg/mL displayed up to 80% of antibacterial activity against S. Typhimurium. Complete inhibition of L. monocytogenes was reached with up to 1.65 mg/mL of SPE. Plant protease extract containing ananain-like enzyme inhibited up to 90% against S. Typhimurium and up to 85% against L. monocytogenes using only 10 µg/mL of the partial-purified enzyme.