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1.
Carbohydr Polym ; 297: 120036, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36184145

RESUMO

Bacterial extracellular membrane vesicles (EMVs) play an active role in many physiological and pathogenic processes. Here, we report the identification and the detailed structural characterization of the capsular polysaccharide from both cells and EMVs from Shewanella vesiculosa by NMR and chemical analysis. The polysaccharide consists of a pentasaccharide repeating unit containing neutral monosaccharides together with amino sugars, of which one has never been isolated from a natural source. The adhesion ability of the polymer both on synthetic surfaces, such as polystyrene nanoparticles and on vesicles with a bilayer mimicking the bacterial membrane in the presence and absence of lipopolysaccharide was investigated. In both cases, a "CPS-corona" that could be the first stage of biofilm formation was observed. The polymer also activates Caspases on colon cancer cells, making S. vesiculosa EMVs as natural nanocarriers for drug delivery.


Assuntos
Lipopolissacarídeos , Poliestirenos , Adesividade , Amino Açúcares , Caspases , Lipopolissacarídeos/farmacologia , Monossacarídeos , Polissacarídeos , Shewanella
2.
Int J Mol Sci ; 23(3)2022 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-35163128

RESUMO

Aeromonas species are found in the aquatic environment, drinking water, bottled mineral water, and different types of foods, such as meat, fish, seafood, or vegetables. Some of these species are primary or opportunistic pathogens for invertebrates and vertebrates, including humans. Among the pathogenic factors associated with these species, there are the lipopolysaccharides (LPSs). LPSs are the major components of the external leaflet of Gram-negative bacterial outer membrane. LPS is a glycoconjugate, generally composed of three portions: lipid A, core oligosaccharide, and O-specific polysaccharide or O-antigen. The latter, which may be present (smooth LPS) or not (rough LPS), is the most exposed part of the LPS and is involved in the pathogenicity by protecting infecting bacteria from serum complement killing and phagocytosis. The O-antigen is a polymer of repeating oligosaccharide units with high structural variability, particularly the terminal sugar, that confers the immunological specificity to the O-antigen. In this study, we established the structure of the O-chain repeating unit of the LPS from Aeromonas bivalvium strain 868 ET (=CECT 7113T = LMG 23376T), a mesophilic bacterium isolated from cockles (Cardium sp.) and obtained from a retail market in Barcelona (Spain), whose biosynthesis core LPS cluster does not contain the waaE gene as most of Aeromonas species. After mild acid hydrolysis, the lipid A was removed by centrifugation and the obtained polysaccharide was fully characterized by chemical analysis and NMR spectroscopy. The polymer consists of a heptasaccharide repeating unit containing D-GalNAc, L-Rha, D-GlcNAc, and D-FucNAc residues.


Assuntos
Aeromonas/metabolismo , Lipídeo A/química , Lipopolissacarídeos/química , Lipopolissacarídeos/metabolismo , Antígenos O/química , Polímeros/química , Sequência de Carboidratos , Hidrólise
3.
Carbohydr Polym ; 278: 118908, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-34973729

RESUMO

Among the widespread malignancies colorectal cancer is the most lethal. Treatments of this malignant tumor include surgery for lesions and metastases, radiotherapy, immunotherapy, and chemotherapy. Nevertheless, novel therapies to reduce morbidity and mortality are demanding. Natural products, such as polysaccharides, can be a valuable alternative to sometimes very toxic chemotherapeutical agents, also because they are biocompatible and biodegradable biomaterials. Microbial polysaccharides have been demonstrated to fulfill this requirement. In this paper, the results about the structure and the activity of a capsular polysaccharide isolated from the psychrotroph Pseudoalteromonas nigrifaciens Sq02-Rifr, newly isolated from the fish intestine, have been described. The characterization has been obtained by spectroscopic and chemical methods, and it is supported by the bioinformatic analysis. The polymer activates Caspases 3 and 9 on colon cancer cells CaCo-2 and HCT-116, indicating a promising antitumor effect, and suggesting a potential capacity of CPS to induce apoptosis.


Assuntos
Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Caspases/metabolismo , Neoplasias do Colo/tratamento farmacológico , Polissacarídeos/farmacologia , Pseudoalteromonas/química , Antineoplásicos/química , Caspases/genética , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Neoplasias do Colo/metabolismo , Neoplasias do Colo/patologia , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Polissacarídeos/química , Células Tumorais Cultivadas
4.
Mar Drugs ; 19(11)2021 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-34822517

RESUMO

Lipopolysaccharides (LPS) are surface glycoconjugates embedded in the external leaflet of the outer membrane (OM) of the Gram-negative bacteria. They consist of three regions: lipid A, core oligosaccharide (OS), and O-specific polysaccharide or O-antigen. Lipid A is the glycolipid endotoxin domain that anchors the LPS molecule to the OM, and therefore, its chemical structure is crucial in the maintenance of membrane integrity in the Gram-negative bacteria. In this paper, we reported the characterization of the lipid A and OS structures from Pseudoalteromonas nigrifaciens Sq02-Rifr, which is a psychrotrophic Gram-negative bacterium isolated from the intestine of Seriola quinqueradiata. The immunomodulatory activity of both LPS and lipid A was also examined.


Assuntos
Peixes , Fatores Imunológicos/farmacologia , Lipopolissacarídeos/farmacologia , Pseudoalteromonas , Animais , Organismos Aquáticos , Células CACO-2/efeitos dos fármacos , Humanos , Fatores Imunológicos/química , Lipopolissacarídeos/química , NF-kappa B/efeitos dos fármacos , Relação Estrutura-Atividade
5.
Carbohydr Res ; 497: 108125, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32905875

RESUMO

Pseudomonas ANT_J38B is a Gram-negative bacterium isolated from an Antarctic island. LPS was extracted using the phenol/chloroform/petroleum ether method. A mild acid hydrolysis followed by a gel filtration purification afforded the O-chain. The polysaccharide was characterized by means of chemical analyses and NMR spectroscopy. The O-chain displays a disaccharide repeating unit with the following backbone: →4)-α-l-GulpNAc3OAcAN-(1 â†’3)-ß-d-QuipNAc-(1→ .


Assuntos
Antígenos O/química , Antígenos O/isolamento & purificação , Pseudomonas/química , Sequência de Carboidratos , Hidrólise , Solventes/química
6.
Mar Drugs ; 18(5)2020 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-32349432

RESUMO

Bacterial extracellular membrane vesicles (EMVs) are membrane-bound particles released during cell growth by a variety of microorganisms, among which are cold-adapted bacteria. Shewanella vesiculosa HM13, a cold-adapted Gram-negative bacterium isolated from the intestine of a horse mackerel, is able to produce a large amount of EMVs. S. vesiculosa HM13 has been found to include a cargo protein, P49, in the EMVs, but the entire mechanism in which P49 is preferentially included in the vesicles has still not been completely deciphered. Given these premises, and since the structural study of the components of the EMVs is crucial for deciphering the P49 transport mechanism, in this study the complete characterization of the lipooligosaccharide (LOS) isolated from the cells and from the EMVs of S. vesiculosa HM13 grown at 18 °C is reported. Both lipid A and core oligosaccharide have been characterized by chemical and spectroscopic methods.


Assuntos
Shewanella/metabolismo , Animais , Vesículas Extracelulares/química , Vesículas Extracelulares/metabolismo , Lipopolissacarídeos/química , Lipopolissacarídeos/metabolismo , Espectrometria de Massas , Perciformes , Relação Estrutura-Atividade
7.
ACS Omega ; 4(1): 688-698, 2019 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-31459356

RESUMO

The growing production of biodiesel as a promising alternative and renewable fuel led as the main problem the dramatic increase of its by-product: glycerol. Different strategies for glycerol derivatization have been reported so far, some more efficient or sustainable than others. Herein, we report a very promising and eco-friendly transformation of glycerol in nontoxic solvents and chemicals (i.e., solketal, ketals), proposing three new families of Fe(III) compounds capable of catalysing glycerol acetalization with unpublished turn over frequencies (TOFs), and adhering most of the principles of green chemistry. The comparison between the activity of complexes of formula [FeCl3(1-R)] (1-R = substituted pyridinimine), [FeCl(2-R,R')] (2-R,R' = substituted O,O'-deprotonated salens) and their corresponding simple salts reveals that the former are extremely convenient because they are able to promote solketal formation with excellent TOFs, up to 105 h-1. Satisfactory performances were shown with respect to the entire range of substrates, with results being competitive to those reported in the literature so far. Moreover, the experimental activity was supported by an accurate and complete ab initio study, which disclosed the fundamental role of iron(III) as Lewis acid in promoting the catalytic activity. The unprecedented high activity and the low loading of the catalyst, combined with the great availability and the good eco-toxicological profile of iron, foster future applications of this catalytic process for the sustainable transformation of an abundant by-product in a variety of chemicals.

8.
Mar Drugs ; 17(1)2019 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-30626008

RESUMO

Shewanella sp. HM13 is a cold-adapted Gram-negative bacterium isolated from the intestine of a horse mackerel. It produces a large amount of outer membrane vesicles (OMVs), which are particles released in the medium where the bacterium is cultured. This strain biosynthesizes a single major cargo protein in the OMVs, a fact that makes Shewanella sp. HM13 a good candidate for the production of extracellular recombinant proteins. Therefore, the structural characterization of the components of the vesicles, such as lipopolysaccharides, takes on a fundamental role for understanding the mechanism of biogenesis of the OMVs and their applications. The aim of this study was to investigate the structure of the oligosaccharide (OS) isolated from Shewanella sp. HM13 cells as the first step for a comparison with that from the vesicles. The lipooligosaccharide (LOS) was isolated from dry cells, purified, and hydrolyzed by alkaline treatment. The obtained OS was analyzed completely, and the composition of fatty acids was obtained by chemical methods. In particular, the OS was investigated in detail by ¹H and 13C NMR spectroscopy and MALDI-TOF mass spectrometry. The oligosaccharide was characterized by the presence of a residue of 8-amino-3,8-dideoxy-manno-oct-2-ulosonic acid (Kdo8N) and of a d,d-heptose, with both residues being identified in other oligosaccharides from Shewanella species.


Assuntos
Membrana Celular/química , Lipopolissacarídeos/química , Shewanella , Adaptação Fisiológica , Regiões Antárticas , Configuração de Carboidratos , Temperatura Baixa , Espectroscopia de Ressonância Magnética
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