Percorrer por autor "Cardelle-Cobas, A."
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- Chitooligosaccharides modified by maillard reaction with glucose inhibit adhesion of enteropathogenic bacteria to mucinPublication . Montenegro, M. I.; Cardelle-Cobas, A.; Gullón, P.; Tavaria, Freni; Pintado, M. E.; Gullón, B.Antiadhesive capacity is a relevant property attributed to some prebiotic oligosaccharides that may confer health benefits. Specifically, these oligosaccharides may directly inhibit infections by enteric pathogens due to their ability to structurally mimic the pathogen binding sites that coat the surface of gastrointestinal epithelial cells. Chitooligosaccharides (COS) are oligomers composed of glucosamine and N-acetyl glucosamine units, linked by β(1→4) bonds and it has been shown that they possess better biological activities than chitosan. Due to this structure, similar to prebiotic oligosaccharides, they appear to be a promising substrate to obtain new prebiotic ingredients with antiadhesive properties. However, previous research works indicate that COS cannot be used directly as prebiotic since the presence of the amino groups in its molecule confers it with an important antimicrobial activity, which could cause a decrease in the bacterial host population with negative health outcomes. Chemical modification of chitosan by substitution of their amino groups eliminate this antimicrobial effect and convert this new COS in a new interesting prebiotic ingredient. In the present study, modified COS with glucose through the Maillard reaction were obtained. Chitosan was the starting material and two different mechanisms were used in this conversion. In the first one, COS were obtained by hydrolysis of chitosan, followed by addition of glucose through a Maillard reaction. The second mechanism consisted in a first step of chitosan modification with glucose through Maillard reaction and a second step of hydrolysis of this modified chitosan in order to obtain the final modified COS. The use of both mechanisms allowed the obtention of modified COS with a similar molecular weight and different degrees of substitution (DS). Once, the modified COSwereobtained, their ability, to inhibit the adhesion of several food pathogens (Escherichia coli, Salmonella enteritidis and Bacillus cereus) to mucin was evaluated “in vitro”. A classical mucin adhesion test was carried out using a fluorescence-based method for the detection of adhesive properties of pathogenic strains. Results showed that both products were capable of inhibiting the adhesion of all tested pathogens. These substrates showed a strain-dependent effect, suggesting the involvement of different carbohydrate-recognition sites. The DS also had a clear effect on the anti-adhesive properties of the derivatives. Although more studies are necessary to further evidence of their biological effects, this work is a basis for future work showing the ability of modified COS to competitively exclude intestinal pathogens and amplify COS uses as a potential prebiotic ingredient.
- Chitosan in oral health: a proof of conceptPublication . Costa, E. M.; Silva, Sara; Cardelle-Cobas, A.; Madureira, A. R.; Ferreira, M. O.; Tavaria, Freni K.; Pintado, M. M.Nowadays chitosan has established itself as a high sought material due to its biocompatibility, reduced toxicity and highpercentage of amino groups that confer it specific functionalities, including antimicrobial activity and acceleration of woundhealing, and studies into chitosan’s applicability have shown chitosan’s potential and feasibility. One of the possible fieldsof application for chitosan based products is the oral cavity, since several of the existing oral health products possesssecondary effects. The aim of this work was to prove that chitosan is a feasible component for oral health productsbiofabrication. As such a chitosan based mouthwash was developed and validated through assessment ofin vitroandin vivoantimicrobial activity, antibiofilm activity and sensory properties. The results obtained showed that it was possible tosuccessfully incorporate chitosan in an oral care product while retaining a considerable antimicrobial activity.In vitrotestingdemonstrated that the chitosan mouthwash possessed a wide range of antimicrobial activity against oral pathogens andwas capable of inhibiting microbial adherence and biofilm formation. Direct comparison with two commercial mouthwashesshowed that the chitosan mouthwash possessed stronger activity than both reference samples.In vivotesting showedthat the chitosan mouthwash was very effective in reducing enterococci and streptococci bacterial counts up to 30 min.after rinsing. Overall, the present shows a successful development of a chitosan-based product and is a tangible proof ofconcept for future utilization of chitosan in oral health.
- Chitosan mouthwash: toxicity and in vivo validationPublication . Costa, E. M.; Silva, S.; Costa, M. R.; Pereira, M.; Campos, D. A.; Odila, J.; Madureira, A. R.; Cardelle-Cobas, A.; Tavaria, F. K.; Rodrigues, A. S.; Pintado, M. M.A previous study showed that a chitosan mouthwash would be a valid alternative to current mouthwashesas it demonstrated, in vitro, significantly higher antibiofilm activity than two commercial mouthwashes.As such, the aim of this work was to verify the safety of the developed product and to validate, in vivo, thebiological activity ascertained in vitro. Chitosan mouthwash safety was evaluated through Ames, MTT andV79 chromosomal aberration assay while antimicrobial activity was evaluated through in vivo assays. Theresults showed that the chitosan mouthwash was safe, presenting lower cytotoxicity than a commercialmouthwash, and that it effectively reduced viable counts of Streptococcus spp. and Enterococcus spp. by ca.5.5 log of CFU. Furthermore, in direct comparison with a commercial mouthwash the chitosan mouthwashpossessed significantly higher antimicrobial activity. The conjunction of these results proves that thechitosan mouthwash is a safe, effective, natural alternative to the existent chemical mouthwashes.
- A comprehensive study into the impact of a chitosan mouthwash upon oral microorganism's biofilm formation in vitroPublication . Costa, E. M.; Silva, S.; Madureira, A. R.; Cardelle-Cobas, A.; Tavaria, F.K.; Pintado, M. E.Modern dentistry emphasizes the importance of dental plaque control to improve oral health. To that endthe development of oral care formulations has been geared toward the incorporation of antiplaque agentsthat may play a crucial role in oral health maintenance. In later years the research into antiplaque agentshas led to the discovery of compounds with significant capability to affect biofilm formation. Among thesecompounds was chitosan, a polysaccharide which showed great ability to interfere with Streptococcusmutans biofilm formation. As such the aim of this work was to incorporate chitosan into a mouthwashmatrix and assess its effect upon biofilm formation of oral microorganisms. This assessment was per-formed via study of the impact the mouthwash upon microbial adherence, biofilm formation and maturebiofilms. Additionally, the action of the chitosan mouthwash was compared with two commerciallyavailable mouthwashes. The results here obtained show that only the chitosan containing mouthwashwas capable of interfering with all microorganisms’ adherence, biofilm formation and mature biofilmswhile at the same time showing vastly superior activity than both commercial mouthwashes assayed.As such a chitosan mouthwash shows great potential as a natural and efficient alternative to traditionalmouthwashes.
- Development of oral films containing chitosanPublication . Cardelle-Cobas, A.; Madureira, A. R.; Costa, E.; Tavaria, Freni; Pintado, M. E.
- Influence of chitooligosaccharide derivatives obtained by Maillard reaction on the growth of probiotic bacteriaPublication . Cardelle-Cobas, A.; Martins, M.; Gullón, B.; Gullón, P.; Tavaria, Freni; Pintado, M. E.
- A novel direct contact method for the assessment of the antimicrobial activity of dental cementsPublication . Costa, E. M.; Silva, S.; Madureira, A. R.; Cardelle-Cobas, A.; Tavaria, F. K.; Pintado, M. M.Dental cements are a crucial part of the odontological treatment, however, due to the hazardous nature and reduced biological efficiency of some of the used materials, newer and safer alternatives are needed, particularly so those possessing higher antimicrobial activity than their traditional counterparts. The evaluation of the antimicrobial properties of solid and semi-solid antimicrobials, such as dental cements and gels, is challenging, particularly due to the low sensitivity of the current methods. Thus, the main aim of this study was the evaluation of the antimicrobial activity of a novel chitosan containing dental cement while simultaneous assessing/validating a new, more efficient, method for the evaluation of the antimicrobial activity of solid and gel like materials. The results obtained showed that the proposed method exhibited a higher sensitivity than the standard 96 well microtiter assay and allowed the determination of bactericidal activity. Additionally, it is interesting to note that the chitosan containing cement, which presented higher antimicrobial activity than the traditional zinc oxide/eugenol mix, was capable of inducing a viable count reduction above 5 log of CFU for all of the studied microorganisms.
- Probiotic adherence to HaCat cells in vitro and competition with pathogensPublication . Rêgo, Â.; Moreira, D.; Cardelle-Cobas, A.; Gullón, P.; Keating, E.; Tavaria, Freni
- Probiotic bacteria as inhibitors of quorum sensing and biofilm formation upon skin pathogensPublication . Lopes, E.; Moreira, D. A.; Gullón, P.; Gullón, B.; Cardelle-Cobas, A.; Tavaria, F. K.
- Synthesis optimization and structural characterization of chitosan-glucose derivative obtained by the Maillard reactionPublication . Montenegro, M. I.; Cardelle-Cobas, A.; Gullón, B.; Ruiz-Matute, A.; Corzo, N.; Pintado, M.M.Several strategies have been applied in order to expand the functional properties of chitosan and its applicability. One of the most successful is the introduction of hydrophilic residues in the chitosan molecule via formation of covalent bonds with the reactive amino groups that may provide it higher solubility (allowing application in more diverse food matrices) and more functional properties, namely prebiotic activity (allowing the development of new functional foods). The Maillard reaction is one of the most important used reactions. Several authors have carried out this kind of chitosan modification obtaining new derivatives with better functional properties. For that, the aim of this work was to optimize the synthesis of a chitosan (Chit)-glucose (Glc) derivative by the Maillard reaction as well as to carry out a complete structural characterization of the obtained derivative. Reaction conditions, evaluating the extent of the Maillard reaction, were optimized by varying temperature (40-80 °C), Glc concentration, and reaction time (0-72 h). Assessment of the reaction extent was carried out by measurements of absorbance and fluorescence. Structural characterization of the derivative was performed by different methodologies in order to determine the molecular weight (Mw) of the derivative, the degree of substitution (DS) and, to confirm the structure of the new derivative, a colloid titration method, High-Performance Liquid Chromatography-Size Exclusion Chromatography (HPLC-SEC), Fourier Transform Infrared Spectroscopy (FT-IR) and Proton Nuclear Magnetic Resonance (1H-NMR) were used. The results obtained, regarding the extent of the reaction, allowed to determine the optimal conditions being: 2% (w/v) of chitosan, 2% (w/v) of Glc, 60 °C and 32 h of reaction time. Structural characterization confirmed the successful introduction of the glucose into the chitosan molecule obtaining a Chit-Glc derivative with a Mw of 76 ±4.25 and a DS of 64.76 ±4.40 %.