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1.
Phys Rev Lett ; 129(19): 191103, 2022 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-36399757

RESUMO

Impulsive supernova feedback and nonstandard dark matter models, such as self-interacting dark matter (SIDM), are the two main contenders for the role of the dominant core formation mechanism at the dwarf galaxy scale. Here we show that the impulsive supernova cycles that follow episodes of bursty star formation leave distinct features in the distribution function of stars: groups of stars with similar ages and metallicities develop overdense shells in phase space. If cores are formed through supernova feedback, we predict the presence of such features in star-forming dwarf galaxies with cored host halos. Their systematic absence would favor alternative dark matter models, such as SIDM, as the dominant core formation mechanism.

2.
Molecules ; 27(3)2022 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-35163966

RESUMO

Pseudomonas aeruginosa infections have become more challenging to treat and eradicate due to their ability to form biofilms. This study aimed to produce hydrophobic nanoparticles by grafting 11-carbon and three-carbon alkyl chains to a chitosan polymer as a platform to carry and deliver carvacrol for improving its antibacterial and antibiofilm properties. Carvacrol-chitosan nanoparticles showed ζ potential values of 10.5-14.4 mV, a size of 140.3-166.6 nm, and an encapsulation efficiency of 25.1-68.8%. Hydrophobic nanoparticles reduced 46-53% of the biomass and viable cells (7-25%) within P. aeruginosa biofilms. Diffusion of nanoparticles through the bacterial biofilm showed a higher penetration of nanoparticles created with 11-carbon chain chitosan than those formulated with unmodified chitosan. The interaction of nanoparticles with a 50:50 w/w phospholipid mixture at the air-water interface was studied, and values suggested that viscoelasticity and fluidity properties were modified. The modified nanoparticles significantly reduced viable P. aeruginosa in biofilms (0.078-2.0 log CFU·cm-2) and swarming motility (40-60%). Furthermore, the formulated nanoparticles reduced the quorum sensing in Chromobacterium violaceum. This study revealed that modifying the chitosan polarity to synthesize more hydrophobic nanoparticles could be an effective treatment against P. aeruginosa biofilms to decrease its virulence and pathogenicity, mainly by increasing their ability to interact with the membrane phospholipids and penetrate preformed biofilms.


Assuntos
Biofilmes/efeitos dos fármacos , Cimenos/farmacologia , Pseudomonas aeruginosa/efeitos dos fármacos , Antibacterianos/farmacologia , Quitosana/química , Cimenos/química , Nanopartículas/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Pseudomonas aeruginosa/patogenicidade , Percepção de Quorum/efeitos dos fármacos , Virulência , Fatores de Virulência
3.
Phys Rev Lett ; 124(14): 141102, 2020 Apr 10.
Artigo em Inglês | MEDLINE | ID: mdl-32338958

RESUMO

We study evolution of self-interacting dark matter subhalos in the Milky Way tidal field. The interaction between the subhalos and the Milky Way's tides lead to more diverse dark matter distributions in the inner region, compared to their cold dark matter counterparts. We test this scenario with two Milky Way satellite galaxies, Draco and Fornax, opposite extremes in the inner dark matter content, and find that they can be accommodated within the self-interacting dark matter model proposed to explain the diverse rotation curves of spiral galaxies in the field.

4.
Phys Rev Lett ; 123(14): 141301, 2019 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-31702225

RESUMO

In hierarchical models of structure formation, the first galaxies form in low-mass dark matter potential wells, probing the behavior of dark matter on kiloparsec scales. Even though these objects are below the detection threshold of current telescopes, future missions will open an observational window into this emergent world. In this Letter, we investigate how the first galaxies are assembled in a "fuzzy" dark matter (FDM) cosmology where dark matter is an ultralight ∼10^{-22} eV boson and the primordial stars are expected to form along dense dark matter filaments. Using a first-of-its-kind cosmological hydrodynamical simulation, we explore the interplay between baryonic physics and unique wavelike features inherent to FDM. In our simulation, the dark matter filaments show coherent interference patterns on the boson de Broglie scale and develop cylindrical solitonlike cores, which are unstable under gravity and collapse into kiloparsec-scale spherical solitons. Features of the dark matter distribution are largely unaffected by the baryonic feedback. On the contrary, the distributions of gas and stars, which do form along the entire filament, exhibit central cores imprinted by dark matter-a smoking gun signature of FDM.

5.
Molecules ; 23(11)2018 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-30380712

RESUMO

The objective of this study was to evaluate the effect of combining catechin, protocatechuic, and vanillic acids against planktonic growing, adhesion, and biofilm eradication of uropathogenic Escherichia coli (UPEC), as well as antioxidant agents. The minimum inhibitory concentrations (MIC) of protocatechuic, vanillic acids and catechin against the growth of planktonic bacteria were 12.98, 11.80, and 13.78 mM, respectively. Mixing 1.62 mM protocatechuic acid + 0.74 mM vanillic acid + 0.05 mM catechin resulted in a synergistic effect acting as an MIC. Similarly, the minimum concentrations of phenolic compounds to prevent UPEC adhesion and biofilm formation (MBIC) were 11.03 and 7.13 mM of protocatechuic and vanillic acids, respectively, whereas no MBIC of catechin was found. However, combinations of 1.62 mM protocatechuic acid + 0.74 mM vanillic acid + 0.05 mM catechin showed a synergistic effect acting as MBIC. On the other hand, the minimum concentrations to eradicate biofilms (MBEC) were 25.95 and 23.78 mM, respectively. The combination of 3.20 mM protocatechuic acid, 2.97 mM vanillic acid, and 1.72 mM catechin eradicated pre-formed biofilms. The antioxidant capacity of the combination of phenolics was higher than the expected theoretical values, indicating synergism by the DPPH•, ABTS, and FRAP assays. Effective concentrations of catechin, protocatechuic, and vanillic acids were reduced from 8 to 1378 times when combined. In contrast, the antibiotic nitrofurantoin was not effective in eradicating biofilms from silicone surfaces. In conclusion, the mixture of phenolic compounds was more effective in preventing cell adhesion and eradicating pre-formed biofilms of uropathogenic E. coli than single compounds and nitrofurantoin, and showed antioxidant synergy.


Assuntos
Antibacterianos/farmacologia , Catequina/farmacologia , Hidroxibenzoatos/farmacologia , Ácido Vanílico/farmacologia , Antibacterianos/química , Antioxidantes/química , Antioxidantes/farmacologia , Biofilmes/efeitos dos fármacos , Catequina/química , Humanos , Hidroxibenzoatos/química , Testes de Sensibilidade Microbiana , Plâncton/efeitos dos fármacos , Escherichia coli Uropatogênica/efeitos dos fármacos , Escherichia coli Uropatogênica/patogenicidade , Ácido Vanílico/química
6.
J Sci Food Agric ; 98(7): 2461-2474, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29023758

RESUMO

Agave leaves are considered a by-product of alcoholic beverage production (tequila, mezcal and bacanora) because they are discarded during the production process, despite accounting for approximately 50% of the total plant weight. These by-products constitute a potential source of Agave extracts rich in bioactive compounds, such as saponins, phenolic compounds and terpenes, and possess different biological effects, as demonstrated by in vitro and in vivo tests (e.g. antimicrobial, antifungal, antioxidant, anti-inflammatory, antihypertensive, immunomodulatory, antiparasitic and anticancer activity). Despite their positive results in biological assays, Agave extracts have not been widely evaluated in food systems and pharmaceutical areas, and these fields represent a potential route to improve the usage of Agave plants as food additives and agents for treating medical diseases. © 2017 Society of Chemical Industry.


Assuntos
Agave/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Bebidas Alcoólicas/análise , Animais , Humanos , Folhas de Planta/química , Resíduos/análise
7.
J Food Sci Technol ; 55(11): 4413-4423, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30333637

RESUMO

Agave plants contain different bioactive compounds that are related to different biological activities; however, the application of Agave as a food additive has rarely been evaluated. The objective of this study was to evaluate the antioxidant and antimicrobial potential of Agave angustifolia extract (AAE) on pork patties stored at 4 °C during 10 days. According to the spectrophotometric analysis, AAE contained phenolic compounds and saponins. In addition, AAE exhibited antioxidant activity based on DPPH, ABTS and FRAP assays (94.2, 239.1 and 148.8 µmol ET/g, respectively). Likewise, AAE showed bactericidal activity against Staphylococcus epidermidis (60 mg/mL) and Escherichia coli (60 mg/mL). AAE demonstrated a protective effect against oxidative processes (TBARS and metmyoglobin) in patties compared to the control group. Mesophilic and psychotropic counts showed that AAE exhibited a weak antimicrobial effect. AAE showed a protective effect on redness and lightness (at 3 and 10 days of storage, respectively). Sensory evaluation found that AAE had no effect on the analyzed parameters. AAE exhibited antioxidant activity that preserve quality and extended the shelf life of pork patties.

8.
J Food Sci Technol ; 51(9): 1674-85, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25190824

RESUMO

Edible coatings can extend the shelf-life of many foods, controlling moisture and solute migration, gas exchange and oxidative reaction rates. Besides, edible coatings can be used as carriers of bioactive compounds to improve the quality of food products such as antioxidants, antimicrobials, flavors and probiotics. These approaches can be useful to extend shelf-life as well as provide a functional product. When edible coatings are used as a matrix holding bioactive compounds remarkable benefits arise; off odors and flavors can be masked, bioactive compounds are protected from the environment, and controlled release is allowed. In this sense, the present review will be focused on analyzing the potential use of encapsulation with edible coatings to incorporate bioactive compounds, solving the disadvantages of direct application.

9.
Foods ; 13(14)2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-39063306

RESUMO

The Special Issue "Plant Extracts Used to Control Microbial Growth: Efficacy, Stability and Safety Issues for Food Applications" explored the potential of plant-based extracts as natural antimicrobial agents in the food industry. Its purpose was to address the growing demand for natural, safe, and effective food preservation methods. The contributions highlighted various plant extracts' antimicrobial efficacy, including phenolic compounds, terpenes, and other bioactive substances. Research papers and one review were submitted from countries, including Spain, Portugal, Italy, Mexico, Turkey, India, USA, Romania, China, and Lithuania, showcasing a diverse international collaboration. Key topics covered in this issue included the chemical characterization of plant extracts, their stability under different processing and storage conditions, and their safety assessments. Advances were reported in using plant extracts to inhibit spoilage microorganisms and foodborne pathogens, enhance food safety, and extend shelf life. The published papers in the Special Issue studied various food types, including yogurt, catfish fillets, edible Mushrooms, red grapes, herring Fillets, and various food types covered in the review. This diversity demonstrates the broad applicability of plant extracts across different food products. Notable findings included the antimicrobial activities of fermented grapevine leaves, grapefruit seed extract, cinnamaldehyde, clove oil, and other plant-based compounds. In conclusion, this Special Issue demonstrated significant progress in applying plant extracts for food preservation, highlighting their potential to contribute to safer and more sustainable food systems worldwide.

10.
Int J Biol Macromol ; 263(Pt 2): 129991, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38331078

RESUMO

This study developed a composite film for packaging refrigerated common carp fillets using carboxymethyl cellulose (CMC) (1.5 % w/v)/Myrrh gum (MG) (0.25 % w/v) base with the addition of titanium dioxide nanoparticles (TiO2 NPs) (0.25 %, 0.5 %, and 1 %) and Dill essential oil (DEO) (1.5 %, 2.25 %, and 3 %). The film was produced using a casting method and optimized for mechanical and barrier properties. The incorporation of DEO and TiO2 NPs into CMC/MG composite films significantly reduced moisture content (MC) and water vapor permeability (WVP), improved their tensile strength (TS), and increased their antimicrobial and antioxidant properties. Moreover, MG can improve the physicomechanical properties of the CMC/MG composite films. The film components had good compatibility without significant aggregation or cracks. In conclusion, the optimized CMC/MG (1.5 %/0.25 %) film containing TiO2 NPs (0.5 %), and DEO (2.25 %) has the best overall performance and can be a good source for making edible film. Functionally, this bioactive nanocomposite film significantly increased the shelf life of refrigerated fish fillet samples for 12 days by inhibiting microbial growth and reducing the oxidation rate compared to the control sample. The knowledge obtained from this study can guide the development of bio-nanocomposite and biodegradable food packaging films based on CMC/MG to increase the shelf life of food products and environmental protection.


Assuntos
Anethum graveolens , Carpas , Commiphora , Nanocompostos , Nanopartículas , Óleos Voláteis , Resinas Vegetais , Animais , Carboximetilcelulose Sódica/farmacologia , Carne , Embalagem de Alimentos/métodos , Óleos Voláteis/farmacologia
11.
Biomolecules ; 14(7)2024 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-39062476

RESUMO

The importance of bioactive compounds in agro-industrial by-products of plant origin lies in their direct impacts on human health. These compounds have been shown to possess antioxidant, anti-inflammatory, and antimicrobial properties, contributing to disease prevention and strengthening the immune system. In particular, the antimicrobial action of these compounds emerges as an important tool in food preservation, providing natural alternatives to synthetic preservatives and contributing to combating antimicrobial resistance. Using agro-industrial by-products of plant origin not only addresses the need to reduce waste and promote sustainability but also inaugurates a new era in the formulation of functional foods. From fruit peels to pulps and seeds, these by-products are emerging as essential ingredients in the creation of products that can promote health. Continued research in this area will unveil new applications and properties of these by-products and open doors to a food paradigm in which health and sustainability converge, paving the way to a healthier and more equitable future. The present review presents an overview of our knowledge of agro-industrial by-products and some of their more relevant health-promoting bioactivities.


Assuntos
Anti-Infecciosos , Antioxidantes , Antioxidantes/farmacologia , Antioxidantes/química , Anti-Infecciosos/farmacologia , Anti-Infecciosos/química , Humanos , Agricultura , Plantas/química
12.
Plants (Basel) ; 13(12)2024 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-38931103

RESUMO

Staphylococcus aureus is a Gram-positive bacteria with the greatest impact in the clinical area, due to the high rate of infections and deaths reaching every year. A previous scenario is associated with the bacteria's ability to develop resistance against conventional antibiotic therapies as well as biofilm formation. The above situation exhibits the necessity to reach new effective strategies against this pathogen. Flourensia retinophylla is a medicinal plant commonly used for bacterial infections treatments and has demonstrated antimicrobial effect, although its effect against S. aureus and bacterial biofilms has not been investigated. The purpose of this work was to analyze the antimicrobial and antibiofilm potential of F. retinophylla against S. aureus. The antimicrobial effect was determined using an ethanolic extract of F. retinophylla. The surface charge of the bacterial membrane, the K+ leakage and the effect on motility were determined. The ability to prevent and remove bacterial biofilms was analyzed in terms of bacterial biomass, metabolic activity and viability. The results showed that F. retinophylla presents inhibitory (MIC: 250 µg/mL) and bactericidal (MBC: 500 µg/mL) activity against S. aureus. The MIC extract increased the bacterial surface charge by 1.4 times and the K+ concentration in the extracellular medium by 60%. The MIC extract inhibited the motility process by 100%, 61% and 40% after 24, 48 and 72 h, respectively. The MIC extract prevented the formation of biofilms by more than 80% in terms of biomass production and metabolic activity. An extract at 10 × MIC reduced the metabolic activity by 82% and the viability by ≈50% in preformed biofilms. The results suggest that F. retinophylla affects S. areus membrane and the process of biofilm formation and removal. This effect could set a precedent to use this plant as alternative for antimicrobial and disinfectant therapies to control infections caused by this pathogen. In addition, this shrub could be considered for carrying out a purification process in order to identify the compounds responsible for the antimicrobial and antibiofilm effect.

13.
Int J Biol Macromol ; : 133809, 2024 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-38996893

RESUMO

Persistent bacterial infections are the leading risk factor that complicates the healing of chronic wounds. In this work, we formulate mixtures of polyvinyl alcohol (P), chitosan (CH), collagen (C), and honey (H) to produce nanofibrous membranes with healing properties. The honey effect at concentrations of 0 % (PCH and PCHC), 5 % (PCHC-5H), 10 % (PCHC-10H), and 15 % (PCHC-15H) on the physicochemical, antibacterial, and biological properties of the developed nanofibers was investigated. Morphological analysis by SEM demonstrated that PCH and PCHC nanofibers had a uniform and homogeneous distribution on their surfaces. However, the increase in honey content increased the fiber diameter (118.11-420.10) and drastically reduced the porosity of the membranes (15.79-92.62 nm). The addition of honey reduces the water vapor transmission rate (WVTR) and the adsorption properties of the membranes. Mechanical tests revealed that nanofibers were more flexible and elastic when honey was added, specifically the PCHC-15H nanofibers with the lowest modulus of elasticity (15 MPa) and the highest elongation at break (220 %). Also, honey significantly improved the antibacterial efficiency of the nanofibers, mainly PCHC-15H nanofibers, which presented the best bacterial reduction rates against Staphylococcus aureus (59.84 %), Pseudomonas aeruginosa (47.27 %), Escherichia coli (65.07 %), and Listeria monocytogenes (49.58 %). In vitro tests with cell cultures suggest that nanofibers were not cytotoxic and exhibited excellent biocompatibility with human fibroblasts (HFb) and keratinocytes (HaCaT), since all treatments showed higher or similar cell viability as opposed to the cell control. Based on the findings, PVA-chitosan-collagen-honey nanofibrous membranes have promise as an antibacterial dressing substitute.

14.
Int J Biol Macromol ; : 134343, 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-39097059

RESUMO

Gallic acid is a vegetable-derived and highly bioactive phenolic acid, but its antioxidant capacity is sensitive to environmental conditions. Chitosan is a biopolymer capable of exerting significant protection to various molecules, including phenolic compounds. A chitosan derivative that extends the antioxidant activity of gallic acid was synthesized by click chemistry and characterized by FT-IR, 1H NMR, and antioxidant capacity assays. Our results show that synthesized polymeric solutions and nanoparticles of N-(gallic acid) chitosan were both internalized by rat brain cells, processes that were modulated by extracellular Ca2+ and Na+. Their internalization was supported by dynamic light scattering and ζ-potential analyses, while Ca2+ imaging recordings performed in brain cells revealed the potential biological effect of N-(gallic acid) chitosan. We conclude that the synthesis of an N-(gallic acid) chitosan derivative through click chemistry is viable and may serve as strategy to prolong its antioxidant activity and to study its biological effects in vivo.

15.
Foods ; 12(12)2023 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-37372527

RESUMO

The increasing demand for natural, safe, and sustainable food preservation methods drove research towards the use of plant antimicrobials as an alternative to synthetic preservatives. This review article comprehensively discussed the potential applications of plant extracts, essential oils, and their compounds as antimicrobial agents in the food industry. The antimicrobial properties of several plant-derived substances against foodborne pathogens and spoilage microorganisms, along with their modes of action, factors affecting their efficacy, and potential negative sensory impacts, were presented. The review highlighted the synergistic or additive effects displayed by combinations of plant antimicrobials, as well as the successful integration of plant extracts with food technologies ensuring an improved hurdle effect, which can enhance food safety and shelf life. The review likewise emphasized the need for further research in fields such as mode of action, optimized formulations, sensory properties, safety assessment, regulatory aspects, eco-friendly production methods, and consumer education. By addressing these gaps, plant antimicrobials can pave the way for more effective, safe, and sustainable food preservation strategies in the future.

16.
Antibiotics (Basel) ; 12(10)2023 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-37887240

RESUMO

Acinetobacter baumannii is a nosocomial pathogen known for its ability to form biofilms, leading to persistent infections and antibiotic resistance. The limited effective antibiotics have encouraged the development of innovative strategies such as using essential oils and their constituents. This study evaluated the efficacy of oregano (Lippia graveolens) essential oil (OEO) and its terpene compounds, carvacrol and thymol, in inhibiting A. baumannii biofilms. These treatments showed a minimum inhibitory concentration of 0.6, 0.3, and 2.5 mg/mL and a minimum bactericidal concentration of 1.2, 0.6, and 5 mg/mL, respectively. Sub-inhibitory doses of each treatment and the OEO significantly reduced biofilm biomass and the covered area of A. baumannii biofilms as measured by fluorescence microscopy. Carvacrol at 0.15 mg/mL exhibited the most potent efficacy, achieving a remarkable 95% reduction. Sub-inhibitory concentrations of carvacrol significantly reduced the biofilm formation of A. baumannii in stainless steel surfaces by up to 1.15 log CFU/cm2 compared to untreated bacteria. The OEO and thymol exhibited reductions of 0.6 log CFU/cm2 and 0.4 log CFU/cm2, respectively, without affecting cell viability. Moreover, the terpenes inhibited twitching motility, a crucial step in biofilm establishment, with carvacrol exhibiting the highest inhibition, followed by OEO and thymol. The study provides valuable insights into the potential of terpenes as effective agents against A. baumannii biofilms, offering promising avenues for developing novel strategies to prevent persistent infections and overcome antibiotic resistance.

17.
Antioxidants (Basel) ; 12(4)2023 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-37107236

RESUMO

This review explores the antioxidant properties of oak (Quercus sp.) extracts and their potential application in preventing oxidative rancidity in food products. Oxidative rancidity negatively impacts food quality, causing changes in color, odor, and flavor and reducing the shelf life of products. The use of natural antioxidants from plant sources, such as oak extracts, has gained increasing interest due to potential health concerns associated with synthetic antioxidants. Oak extracts contain various antioxidant compounds, including phenolic acids, flavonoids, and tannins, which contribute to their antioxidative capacity. This review discusses the chemical composition of oak extracts, their antioxidative activity in different food systems, and the safety and potential challenges related to their application in food preservation. The potential benefits and limitations of using oak extracts as an alternative to synthetic antioxidants are highlighted, and future research directions to optimize their application and determine their safety for human consumption are suggested.

18.
Int J Med Mushrooms ; 14(6): 563-73, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23510250

RESUMO

The main objective of this study was to evaluate the antioxidant capacity of methanolic extracts from species of genus Phellinus: Ph. fastuosus, Ph. grenadensis, Ph. Merrillii, and Ph. Badius, in their respective polar fractions (aqueous) and nonpolar extracts (ethyl acetate), through tests of free-radical inactivation and hemolysis inhibition. The fungus species that gave the extract with the highest phenol content, total flavonoids, and antioxidant capacity [DPPH·, Trolox equivalents antioxidant capacity (TEAC), and hemolysis inhibition] was Ph. Merrillii, followed by Ph. fastuosus, Ph. Grenadensis, and Ph. Badius. The antioxidant capacities of the extracts, in descending order, were as follows: Ph. Merrillii (nonpolar), Ph. Fastuosus (nonpolar), Ph. Grenadensis (nonpolar), Ph. Fastuosus (polar), Ph. Merrillii (polar), Ph. Grenadensis (polar), Ph. Badius (nonpolar), and Ph. Badius (polar). Antioxidant capacity in the above Phellinus fungi species had EC50 values for DPPH inhibition of 0.45, 0.88, 1.31, 1.89, 2.14, 2.22, 3.42, and 6.00 mg/mL, respectively; TEAC values of 10400.29, 7635.53, 4855.05, 4415.39, 4041.68, 2989.2, 1937.7, and 842.42 µmol TE/g, respectively; and hemolysis inhibition values of 72.83, 66.95, 50.87, 50.28, 48.5, 42.82, 42.37, and 37.91%, respectively. In general, the fungus extract with the highest antioxidant capacity was the nonpolar fraction of Ph. Merrillii. The Phellinus species studied represent potential natural sources of bioactive compounds with antioxidant activity.


Assuntos
Antioxidantes/química , Basidiomycota/química , Flavonoides/farmacologia , Fenóis/farmacologia , Cromanos/química , Flavonoides/química , Hemólise , Humanos , Metanol , Fenóis/química , Especificidade da Espécie
19.
Toxins (Basel) ; 14(9)2022 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-36136547

RESUMO

Lecithin-dependent thermolabile hemolysin (LDH) is a virulence factor excreted by Vibrio parahaemolyticus, a marine bacterium that causes important losses in shrimp farming. In this study, the function of LDH was investigated through its inhibition by metal ions (Mg2+, Ca2+, Mn2+, Co2+, Ni2+ and Cu2+) and chemical modification reagents: ß-mercaptoethanol (ßME), phenylmethylsulfonyl fluoride (PMSF) and diethyl pyrocarbonate (DEPC). LDH was expressed in the Escherichia coli strain BL-21, purified under denaturing conditions, and the enzymatic activity was evaluated. Cu2+, Ni2+, Co2+ and Ca2+ at 1 mmol/L inhibited the LDH esterase activity by 20−95%, while Mg2+ and Mn2+ slightly increased its activity. Additionally, PMSF and DEPC at 1 mmol/L inhibited the enzymatic activity by 40% and 80%, respectively. Dose-response analysis showed that DEPC was the best-evaluated inhibitor (IC50 = 0.082 mmol/L), followed by Cu2+ > Co2+ > Ni2+ and PMSF (IC50 = 0.146−1.5 mmol/L). Multiple sequence alignment of LDH of V. parahaemolyticus against other Vibrio species showed that LDH has well-conserved GDSL and SGNH motifs, characteristic of the hydrolase/esterase superfamily. Additionally, the homology model showed that the conserved catalytic triad His-Ser-Asp was in the LDH active site. Our results showed that the enzymatic activity of LDH from V. parahaemolyticus was modulated by metal ions and chemical modification, which could be related to the interaction with catalytic amino acid residues such as Ser153 and/or His 393.


Assuntos
Proteínas Hemolisinas , Vibrio parahaemolyticus , Aminoácidos , Dietil Pirocarbonato , Escherichia coli/metabolismo , Esterases , Proteínas Hemolisinas/metabolismo , Hidrolases , Indicadores e Reagentes , Íons , Lecitinas , Mercaptoetanol , Fluoreto de Fenilmetilsulfonil , Vibrio parahaemolyticus/metabolismo , Fatores de Virulência
20.
Pathogens ; 12(1)2022 Dec 26.
Artigo em Inglês | MEDLINE | ID: mdl-36678383

RESUMO

Salmonella can form biofilms that contribute to its resistance in food processing environments. Biofilms are a dense population of cells that adhere to the surface, creating a matrix composed of extracellular polymeric substances (EPS) consisting mainly of polysaccharides, proteins, and eDNA. Remarkably, the secreted substances, including cellulose, curli, and colanic acid, act as protective barriers for Salmonella and contribute to its resistance and persistence when exposed to disinfectants. Conventional treatments are mostly ineffective in controlling this problem; therefore, exploring anti-biofilm molecules that minimize and eradicate Salmonella biofilms is required. The evidence indicated that terpenes effectively reduce biofilms and affect their three-dimensional structure due to the decrease in the content of EPS. Specifically, in the case of Salmonella, cellulose is an essential component in their biofilms, and its control could be through the inhibition of glycosyltransferase, the enzyme that synthesizes this polymer. The inhibition of polymeric substances secreted by Salmonella during biofilm development could be considered a target to reduce its resistance to disinfectants, and terpenes can be regarded as inhibitors of this process. However, more studies are needed to evaluate the effectiveness of these compounds against Salmonella enzymes that produce extracellular polymeric substances.

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