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Postbiotic is the term used to define the soluble factors, metabolic products, or byproducts released by live probiotic bacteria or after its lysis. The objective of this study was to carry out the chemical characterization of the postbiotic of Lacticaseibacillus rhamnosus LR-32 and to evaluate its in vitro effect on the development of the Streptococcus mutans biofilm. After the cultivation of the probiotic strain, the postbiotic was extracted by centrifuging the culture and filtering the supernatant. This postbiotic was characterized by using gas chromatography coupled with mass spectrometry (GC–MS), and then it was used to determine the growth inhibition of S. mutans in its planktonic form; additionally, its effects on the following parameters in 48 h biofilm were evaluated: viable bacteria, dry weight, and gene expression of glucosyltransferases and VicR gene. The control group consisted of the biofilm without any treatment. A paired t-test was performed for statistical analysis, with the p-value set at 5%. Seventeen compounds of various chemical classes were identified in the postbiotic, including sugars, amino acids, vitamins, and acids. The treatment with the postbiotic led to an inhibition of the growth of S. mutans in its planktonic form, as well as a decrease in the number of viable bacteria, reduction in dry weight, and a negative regulation of the gene expression of gtfB, gtfC, gtfD, and vicR in its biofilm state, compared with the nontreated group (p < 0.05). The postbiotic of L. rhamnosus impaired the development of S. mutans biofilm.

Hydrogels are structures that have value for application in the area of tissue engineering because they mimic the extracellular matrix. Naturally obtained polysaccharides, such as chitosan (CH) and cashew gum, are materials with the ability to form polymeric networks due to their physicochemical properties. This research aimed to develop a scaffold based on chitosan and phthalated cashew tree gum and test it as a support for the growth of human mesenchymal stem cells. In this study, phthalation in cashew gum (PCG) was performed by using a solvent-free route. PCG-CH scaffold was developed by polyelectrolyte complexation, and its ability to support adherent stem cell growth was evaluated. The scaffold showed a high swelling rate. The pore sizes of the scaffold were analyzed by scanning electron microscopy. Human dental pulp stem cells (hDPSCs) were isolated, expanded, and characterized for their potential to differentiate into mesenchymal lineages and for their immunophenotypic profile. Isolated mesenchymal stem cells presented fibroblastoid morphology, plastic adhesion capacity, and differentiation in osteogenic, adipogenic, and chondrogenic lineages. Mesenchymal stem cells were cultured in scaffolds to assess cell adhesion and growth. The cells seeded on the scaffold showed typical morphology, attachment, and adequate distribution inside the matrix pores. Thus, cells seeded in the scaffold may improve the osteoinductive and osteoconductive properties of these biomaterials.

This work presents a simple method for the green synthesis of silver nanoparticles (AgNPs) using as reducing and stabilizing agent a polysaccharide extracted from red algae Gracilaria birdiae present in the coast of Piauí. The AgNPS were prepared using three polysaccharide concentrations (0.02, 0.03 and 0.05% v/v) and two pHs (10 and 11) at stirring for 30 min at 90 °C. The formation of silver nanoparticles was monitored by measurements of UV–vis and FTIR and characterized by size and zeta potential measurements using DLS and morphologically by TEM. The UV–vis absorption spectrum showed the surface plasmon peak at 410 nm, which is characteristic peak of silver nanoparticles. The functional biomolecules present in the polysaccharide and the interaction between the nanoparticles were identified by the Fourier transform infrared spectroscopy (FTIR) analysis. The stability of the synthesized silver nanoparticles was analyzed during four months and no significant agglomeration was observed. The hydrodynamic diameter of the AgNPs varied between 20.2 nm and 94.9 nm. The AgNPs were tested for antimicrobial activity using Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) and all samples showed antimicrobial activity against E. coli. Using an environment-friendly, the AgNPs were synthesized in a simple, rapid and one-step process using natural sources as red algae with favorable characteristics such as spherical shape, small size and zeta potential negative. The results suggest that the polysaccharide mediated synthesized silver nanoparticles could be used as a model for future projects of nano-medicines or drug delivery systems. Keywords: Silver nanoparticles, Green synthesis, Algae, Gracilaria birdiae

Streptococcal bacteremia that occurs during invasive dental procedures can lead to infective endocarditis (IE) in children with certain heart diseases. Prior to such procedures, antibiotic prophylaxis (AP) with amoxicillin (AMPC) is recommended. However, the detection of amoxicillin-resistant strains (AMPC-RS) in the mouths of children with heart diseases raises the concern that they would be uncovered by the action of standard AP. This work carried out a systematic review and meta-analysis regarding AMPC-RS carriage in the mouths of children. We consulted databases covering studies between the years 2000 and 2021, following the PRISMA declaration. A meta-analysis was carried out to assess the prevalence of children carrying AMPC-RS in the mouths. The antimicrobial tests were carried out by microdilution (46.2% of articles), disk diffusion (38.3%), and the E-test (15.4%). Streptococcus mitis and S. sanguinis were bacteria with the most found resistance phenotype, with MIC reaching values of 128 µg/mL. Of the 13 selected articles, only 6 presented results that made it possible to calculate the prevalence of children carrying AMPC-RS in their mouths, ranging from 5.5% to 86.3%. Most of the studies were classified as high quality, and the collected data demonstrate the presence of streptococcal strains with different levels of resistance in the collected samples, such as the dental plaque. The meta-analysis pointed to evidence of AMPC-RS being carried, with a prevalence of 21.3% (I² = 0%, p = 0.705). There is an important prevalence of AMPC-RS carriage in the mouths of children. Specific attention should be directed to AP in those susceptible to IE.

RESUMO O uso de plantas medicinais no tratamento de doenças é uma estratégia antiga utilizada por praticamente todas as populações do mundo, e, embora novos antibióticos tenham sido desenvolvidos para o controle de micro-organismos infecciosos, às vezes são ineficazes. Diversos extratos de plantas medicinais têm efeitos antimicrobianos, principalmente quando associados à antibióticos de uso clínico, representando alternativa terapêutica para doenças infecciosas. Montrichardia linifera, conhecida popularmente como aninga, é espécie macrófita, aquática emergente de hábito herbáceo, pertencente a família Araceae e ocorre em áreas alagáveis. A utilidade farmacológica desta espécie é diversificada tendo sido relatada como cicatrizante, antirreumático, antidiurético e expectorante. Devido à relevância no campo etnofarmacológico, ampla utilização na medicina popular e escassez de trabalhos relacionados à atividade antibacteriana desta espécie, objetivou-se com este trabalho avaliar a atividade antibacteriana de extratos alcoólicos de folhas de Montrichardia linifera, coletadas na margem do rio Igaraçu, Parnaíba-PI. O extrato foi testado em oito cepas de bactérias: Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae e Pseudomonas aeruginosa. Foram utilizadas as técnicas de verificação da formação de halos de inibição e determinação das concentrações inibitórias e bactericidas mínimas. Os testes antibacterianos evidenciaram como principais resultados que o extrato metanólico seco (EMS), extrato metanólico fresco (EMF), e o extrato etanólico seco (EES), apresentaram ação antibacteriana, enquanto o extrato etanólico fresco (EEF) não apresentou atividade para as bactérias testadas. O EMS foi o mais eficiente, inibindo o crescimento bacteriano na concentração de 200 μg/mL para E. faecalis, 400 μg/mL para S. aureus, 400 μg/mL para S. epidermidis e 2.000 μg/mL para P. aeruginosa. O EMF obteve CIM de 2.000 μg/mL para E. faecalis e EES obteve CIM de 250 μg/mL para E. faecalis. Os resultados demonstraram que M. linifera constitui fonte eficiente de compostos bioativos antibacterianos. Os estudos sobre as propriedades farmacológicas de plantas da família Araceae são escassos, e os resultados deste trabalho são pioneiros em relação a atividade antibacteriana desta espécie.

Bioactive compounds extracted from natural sources can benefit human health. The aim of this work was to determine total phenolic content and antioxidant activity in extracts of Euphorbia tirucalli L. followed by identification and quantification of the phenolic compounds, as well as their antibacterial activities. Antioxidant activities were determined by DPPH and ABTS•+ assay. Identification of phenolic compounds was performed using high-performance liquid chromatography (HPLC), and antimicrobial activities were verified by agar dilution methods and MIC values. Total phenolic content ranged from 7.73 to 30.54 mg/100 g gallic acid equivalent. Extracts from dry plants showed higher antioxidant activities than those from fresh ones. The DPPH EC50 values were approximately 12.15 μg/mL and 16.59 μg/mL, respectively. Antioxidant activity measured by the ABTS method yielded values higher than 718.99 μM trolox/g for dry plants, while by the Rancimat® system yielded protection factors exceeding 1 for all extracts, comparable to synthetic BHT. Ferulic acid was the principal phenolic compound identified and quantified through HPLC-UV in all extracts. The extracts proved effective inhibitory potential for Staphylococcus epidermidis and Staphylococcus aureus. These results showed that extracts of Euphorbia tirucalli L. have excellent antioxidant capacity and moderate antimicrobial activity. These can be attributed to the high concentration of ferulic acid.

The present study describes the development of a green synthesis of silver nanoparticles reduced and stabilized by exuded gum from Anacardium occidentale L. and evaluates in vitro their antibacterial and cytotoxic activities. Characterization of cashew gum-based silver nanoparticles (AgNPs) was carried out based on UV–Vis spectroscopy, transmission electron microscopy and dynamic light scattering analysis which revealed that the synthesized silver nanoparticles were spherical in shape, measuring about 4 nm in size with a uniform dispersal. AgNPs presented antibacterial activity, especially against Gram-negative bacteria, in concentrations where no significant cytotoxicity was observed.

Silver nanoparticles have been shown to possess considerable antibacterial activity, but in vivo applications have been limited due to the inherent, but low, toxicity of silver. On the other hand, silver nanoparticles could provide cutaneous protection against infection, due to their ability to liberate silver ions via a slow release mechanism, and their broad-spectrum antimicrobial action. Thus, in this work, we describe the development of a carboxymethyl cellulose-based hydrogel containing silver nanoparticles. The nanoparticles were prepared in the hydrogel in situ, utilizing two variants of cashew gum as a capping agent, and sodium borohydride as the reducing agent. This gum is non-toxic and comes from a renewable natural source. The particles and gel were thoroughly characterized through using rheological measurements, UV-vis spectroscopy, nanoparticles tracking analysis, and transmission electron microscopy analysis (TEM). Antibacterial tests were carried out, confirming antimicrobial action of the silver nanoparticle-loaded gels. Furthermore, rat wound-healing models were used and demonstrated that the gels exhibited improved wound healing when compared to the base hydrogel as a control. Thus, these gels are proposed as excellent candidates for use as wound-healing treatments.

This work presents a simple method for the green synthesis of silver nanoparticles (AgNPs) using as reducing and stabilizing agent a polysaccharide extracted from red algae Gracilaria birdiae present in the coast of Piauí. The AgNPS were prepared using three polysaccharide concentrations (0.02, 0.03 and 0.05% v/v) and two pHs (10 and 11) at stirring for 30 min at 90 °C. The formation of silver nanoparticles was monitored by measurements of UV–vis and FTIR and characterized by size and zeta potential measurements using DLS and morphologically by TEM. The UV–vis absorption spectrum showed the surface plasmon peak at 410 nm, which is characteristic peak of silver nanoparticles. The functional biomolecules present in the polysaccharide and the interaction between the nanoparticles were identified by the Fourier transform infrared spectroscopy (FTIR) analysis. The stability of the synthesized silver nanoparticles was analyzed during four months and no significant agglomeration was observed. The hydrodynamic diameter of the AgNPs varied between 20.2 nm and 94.9 nm. The AgNPs were tested for antimicrobial activity using Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) and all samples showed antimicrobial activity against E. coli. Using an environment-friendly, the AgNPs were synthesized in a simple, rapid and one-step process using natural sources as red algae with favorable characteristics such as spherical shape, small size and zeta potential negative. The results suggest that the polysaccharide mediated synthesized silver nanoparticles could be used as a model for future projects of nano-medicines or drug delivery systems. [ABSTRACT FROM AUTHOR]

Pseudomonas aeruginosa is an opportunistic pathogen that causes severe infections in immunocompromised individuals and in patients with cystic fibrosis. A range of vaccines to prevent infections caused by P. aeruginosa has already been tested, yet no vaccine against this pathogen is currently available. The goal of this study was to evaluate the potential of bovine serum albumin nanoparticles (BSA-NPs) associated with total P. aeruginosa ATCC 27853 antigens in inducing protection against the infection with virulent P. aeruginosa PA14 strain in murine model of nasal infection. Swiss mice were immunized with BSA-NPs associated with total P. aeruginosa antigens (NPPa) or empty NPs (NPe). As positive and negative control, groups of animals were immunized with total antigens of P. aeruginosa ATCC 27853 and phosphate buffered saline, respectively. Immunized mice were infected via nasal route using P. aeruginosa PA14 strain. The survival after 48 h was evaluated and the lungs from animals were processed for quantification of bacterial load, cytokine expression and histopathological analysis. After infection with P. aeruginosa PA14, animals immunized with NPPa had the highest survival rate, the lowest bacterial lung load, a controlled production of cytokines and few histopathological changes. These results indicate that NPPa immunization protected mice from infection, contributing for the elimination of the bacteria from the lungs, which consequently reflected the survival of the animals. Therefore, this vaccine was able to induce a functional response in an animal model of lethal infection and thereby is a promising platform for P. aeruginosa vaccines., (Copyright © 2018 Elsevier Ltd. All rights reserved.)