Browsing by Author "Tavaria, F."
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- Anti-inflammatory effect of chitosan oligomersPublication . Spindola, H.; Fernandes, J.; Sousa, V. De; Tavaria, F.; Malcata, F. Xavier; Carvalho, J.E.
- Characterization of Staphylococcus strains collected throughout the production chain of a Ewe’s milk cheese dairy plantPublication . Soares, J.; Marques, M.D.R.; Tavaria, F.; Malcata, F. Xavier; Pintado, M. E.
- Chitosan as an effective inhibitor of multidrug resistant Acinetobacter baumanniiPublication . Costa, E. M.; Silva, S.; Vicente, S.; Veiga, M.; Tavaria, F.; Pintado, M. M.Over the last two decades worldwide levels of antibiotic resistance have risen leading to the appearance of multidrug resistant microorganisms. Acinetobacter baumannii is a known skin pathogen which has emerged as a major cause of nosocomial outbreaks due to its capacity to colonize indwelling medical devices and natural antibiotic resistance. With chitosan being an effective antimicrobial agent against antibiotic resistant microorganisms, the aim of this work was to access its potential as an alternative to traditional antimicrobials in the management of A. baumannii growth. What the results showed was that both chitosan MW’s tested were active upon A. baumannii’s planktonic and sessile growth. For planktonic growth MICs and MBCs were obtained at relatively low concentrations (0.5–2 mg/mL) while for sessile growth chitosan proved to be an effective inhibitor of A. baumannii’s adhesion and biofilm formation. Considering these results chitosan shows a high potential for control of A. baumannii infections.
- Chitosan nanoparticles as alternative anti-staphylococci agents: bactericidal, antibiofilm and antiadhesive effectsPublication . Costa, E. M.; Silva, S.; Vicente, S.; Neto, C.; Castro, P. M.; Veiga, M.; Madureira, R.; Tavaria, F.; Pintado, M. M.Chitosan is a biocompatible, bioactive, non-toxic polymer that due to these characteristics has been widely used as a carrier for targeted delivery of bioactive molecules. In recent years, and considering that chitosan has a strong antimicrobial potential, the scientific community's focus has shifted onto the possible antimicrobial activity of chitosan nanoparticles. With this in mind, the aim of this work was to produce low molecular weight chitosan nanoparticles, through the ionic gelation method and characterize their potential biological activity against three staphylococci (MSSA, MRSA and MRSE) in planktonic and sessile environments. The chitosan nanoparticles produced had an average size of 244 ± 12 nm, an average charge of 17.3 ± 1.4 mV and had a MIC of 1.25 mg/mL for all tested microorganisms. Bactericidal activity was only registered for MSSA and MRSA with the time-inhibition curves showing bactericidal activity within 1 h. Assays regarding chitosan nanoparticles' impact upon sessile populations showed that they were effective in preventing MRSE adhesion and highly effective in reducing MRSA and MSSA biofilm formation.
- Comparison between sensory descriptors and flavour compounds in an ovine Portuguese traditional cheese (Serra da Estrela)Publication . Franco, M. I.; Machado, P.; Teixeira, S.; Monteiro, M. J.; Tavaria, F.; Ferreira, A. C.; Pintado, M. E.; Malcata, F. Xavier
- Development and bioactive potential of films from plant residue enriched with eucalyptus extract and oregano essential oilPublication . Melo, A.; Lopes, A. I.; Barros, L.; Tavaria, F.; Pintado, M.Introduction: Traditional plastic food packaging is typically non-renewable and non- biodegradable, creating a need for new eco-friendly and sustainable alternatives, such as plant- based films. Plant agro-industrial wastes have been explored as sources of polymeric matrices in film development. Additionally, natural compounds from plants, like plant extracts (PEs) and essential oils (EOs) can provide these films with antimicrobial and antioxidant activities. So, this work aimed to produce polymeric films with licorice-based polymers incorporated with eucalyptus extract and oregano EO. Methodology: Licorice residue was characterized using high- performance liquid chromatography (HPLC) and used to develop films with alginate and glycerol. Films were produced with oregano EO (2%), eucalyptus extract (1%), and a combination of both (1% each). The antimicrobial activity was tested against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) using the viable cell method. Antioxidant activity was assessed by 2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-difenil-1-picrilhidrazil (DPPH) scavenging assays. Results: The results showed that the residue consisted mostly of insoluble fibers from approximately 74%, with lignin being the main constituent from approximately 33%. The residue was, then, used to produce films incorporated with eucalyptus extract and oregano EO as bioactive agents. The antimicrobial activity test showed that the films with licorice residue incorporated with eucalyptus extract and oregano oil was able to completely inhibit E. coli after 2 h of exposure; Besides that, the film incorporated with eucalyptus extract was able to completely inhibit S. aureus after 4 h of exposure and the film incorporated with eucalyptus extract and oregano oil inhibited this bacterium after 2 h. Regarding the antioxidant potential of the films, the film with licorice residue (no extract nor oil) was the one with the least antioxidant activity (ABST: 226,7428 Trolox equivalents (μM)/mg film; DPPH: 162,2766 Trolox equivalents (μM)/mg film). The incorporation of eucalyptus extract and oregano EO to the films significantly increased its antioxidant activity. Conclusion: Polymeric films made from licorice residues and incorporated with EOs and PEs, due to their antimicrobial and antioxidant activities, can constitute an alternative to conventional food packaging.
- Effect of alternative technological methodologies on the yeast profile in Serra da Estrela cheesePublication . García-Fontán, M. C.; Tavaria, F.; Reis, P.; Pintado, M. E.; Malcata, F. X.
- A view on polymer-based composite materials for smart wound dressingsPublication . Baptista-Silva, S.; Alves, P.; Guimarães, I.; Borges, S.; Tavaria, F.; Granja, P.; Pintado, M.; Oliveira, A. L.Wound management challenges everyday thousands of health professionals, mainly due to the constant monitoring and difficulties in deciding the correct treatment options. When considering chronic wounds, selecting the ideal dressing defies clinical knowledge, when facing the large amount of different materials, its distinctive properties and the uniqueness of each patient needs. This chapter presents an overview on the challenges and complexity of a chronic wound, exploring the event of awound infection and discussing the large range of polymer-based composite materials and products in use for each specific wound condition, taking into account the key decision aspects defined by the clinicians. Different tissue engineering strategies are also herein addressed with varied reported clinical success, ranging from non-cellularized to considerably sophisticated cellularized products, reproducing the compositional complexity of both dermis and epidermis. Recent advances in smart dressings and sensors are also brought to discussion as sensing the wound can give us new insights about the series of complex biochemical events related to the healing and regeneration process, while contributing for a better wound assessment.
- Wound healing, anti-ulcerogenic, anti-inflammatory and anti-proliferative properties of ChitosanPublication . Tavaria, F.; Jorge, M.; Marchetti, G.; Souza, V.; Ruíz, A. L.; Malcata, F. Xavier; Pintado, M. E.; Carvalho, J.Chitosan, is one of the most abundant, renewable, nontoxic and biodegradable carbohydrate polymers, and is largely available in the exoskeletons of shellfish and insects. It has recently attracted great attention in the pharmaceutical, biomedical and food arenas, due to its favourable physico-chemical and biological properties. In this research effort, we have assessed wound healing, antiulcerogenic and antiinflammatory properties of chitosan in vivo, and the anti-proliferative activity in vitro.We used three chitosans differing in their molecular weight and degree of deacetylation. The wound healing study was performed using healthy adult (250—300 g) maleWistar rats (Rattus norvegicus), n = 5/group. After thiopental anaesthesia, excision wounds sized 1.5cm2 in average were made. Wounds were treated topically for ten days by applying 200_L/wound of each sample (0.2 mg/mL) and protected by a wound curative. On day 11, animals were sacrificed and tissue samples from wound site of each animal were removed for histopathological analysis and for total collagen determination. The anti-ulcerative assay was done in healthy adult (250—300 g) male Wistar rats (R. norvegicus), n = 5/group, using carbenoxolone as a positive control. Compounds were administered orally according to their body weight (1000 mg/kg). After 30 min, each animal received 1mL of absolute ethanol orally. After one hour, animals were sacrificed by cervical displacement and their stomachs were removed, opened along the greater curvature and the ulcerative lesion index was determined. Ear oedema was used to evaluate the anti-inflammatory effect of chitosans in Swiss adult mice (Mus musculus) weighing approximately 30—40 g. Croton oil was used as the inflammatory agent and dexamethazone as positive control. The oedema was measured by subtracting the weight of the ear receiving only acetone (vehicle) by that receiving the irritating agent. The oedema inhibition (%) was determined by the formula: [(wC − wT)/wC] × 100, where wC was the ear weight in the croton oil group and wT was the ear weight in the treatment groups. The anti-proliferative activity of chitosan was evaluated in vitro against eight human tumor cell lines. The Total Growth Inhibition (cytostatic activity) was determined for each compound. The in vitro cytotoxic activity of chitosan was found to be minimal, whereas it showed wound healing ability. The ear oedema assay showed no differences among the croton oil group and chitosan groups, demonstrating no anti-inflammatory activity. High molecular weight chitosan seems to render gut protection, but the medium molecular weight is the best anti-ulcerative compound.