Browsing by Author "Pintado, Manuela E."
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- An eco-friendly and up-scalable approach to extract canthaxanthin from yeast cellsPublication . Pereira, Ana M.; Durão, Joana; Pereira, Joana Odila; Ferreira, Carlos; Faustino, Margarida; Oliveira, Ana Sofia; Pereira, Carla F.; Pintado, Manuela E.; Carvalho, Ana P.Canthaxanthin is a naturally occurring ketocarotenoid pigment present in plants, algae, bacteria and some fungi. In addition to its coloring role, canthaxanthin has an excellent antioxidant activity, thus having additional market demands in the feed, food, cosmetic and pharmaceutical industries. Canthaxanthin can be directly isolated from its natural source or produced by chemical synthesis, but these strategies either result in low yields, or use hazardous solvents, respectively. Therefore, the biosynthesis of canthaxanthin using microbial cell factories is becoming an advantageous alternative. Furthermore, microbial synthesis represents an economic and sustainable approach as it enables the use of agriculture and industrial wastes as substrates. In this work, the extraction, recovery and purification of canthaxanthin from modified yeasts using food grade solvents and up-scalable methodologies was studied. The resulting canthaxanthin-enriched extract was characterized (UV-Vis, PXRD and SEM) and quantified (HPLC), resulting in a canthaxanthin purity of 43.7 % (w/w).
- Anti-inflammatory activity of chitooligosaccharides in vivoPublication . Fernandes, João C.; Spindola, Humberto; Sousa, Vanessa de; Santos-Silva, Alice; Pintado, Manuela E.; Malcata, Francisco Xavier; Carvalho, João E.All the reports to date on the anti-inflammatory activity of chitooligosaccharides (COS) are mostly based on in vitro methods. In this work, the anti-inflammatory activity of two COS mixtures is characterized in vivo (using balb/c mice), following the carrageenan-induced paw edema method. This is a widely accepted animal model of acute inflammation to evaluate the anti-inflammatory effect of drugs. Our data suggest that COS possess anti-inflammatory activity, which is dependent on dose and, at higher doses, also on the molecular weight. A single dose of 500 mg/kg b.w. weight may be suitable to treat acute inflammation cases; however, further studies are needed to ascertain the effect upon longer inflammation periods as well as studies upon the bioavailability of these compounds.
- Antimicrobial activity of edible coatings prepared from whey protein isolate and formulated with various antimicrobial agentsPublication . Ramos, Óscar S.; Santos, Arménia C.; Leão, Mariana V.; Pereira, Joana O.; Silva, Sara I.; Fernandes, João C.; Franco, M. Isabel; Pintado, Manuela E.; Malcata, F. XavierUsing in vitro tests, the efficacy of edible coatings, made using whey protein isolates as a base material and glycerol as a plasticizer, and containing several antimicrobial compounds was assessed upon ubiquitous spoilage microflora in cheese. The formulation that showed the greatest activity was applied onto the surface of experimental cheeses, and their major microbiological and physicochemical features were compared with those of cheese added withcommercial coatings. Chitooligosaccharide (COS) and lactic acid exhibited the highest (P < 0.05) bacteriocidal effect against Gram-negative and Gram-positive bacteria, respectively, whereas sodium benzoate and COS exhibited the highest (P< 0.05) inhibitory effect against the yeast. Combinations of lactic acid and COS yielded the highest (P < 0.05) effect against all microorganisms tested; upon application on the cheese surface, they proved to be more active against bacteria, and less effective against yeasts and moulds (P < 0.05) than their commercial coating counterparts.
- Antimicrobial effects of chitosans and chitooligosaccharides, upon Staphylococcus aureus and Escherichia coli, in food model systemsPublication . Fernandes, João C.; Tavaria, Freni K.; Soares, José C.; Ramos, Óscar S.; Monteiro, M. João; Pintado, Manuela E.; Malcata, F. XavierThe objective of this study was to elucidate the controversial relationship between the molecular weight (MW) of chitosans and their antibacterial activity (upon different inoculum levels, at several concentrations). The influence of food components on the activity was also ascertained, as well as acceptance by a sensory panel. All the compounds tested exhibited antibacterial activity against Staphylococcus aureus and Escherichia coli. This activity was shown to be closely dependent on the inoculum level, MW and concentration used. Within 4 h at 10³ cells/mL, all five compounds, at every concentration (0.5%, 0.25% and 0.1%, w/v), proved to be bactericidal; for higher inocula, 0.1% (w/v) was only bacteriostatic; at 107 or 105 cells/mL, and independently of the inoculum level, 0.25% (w/v) of any chitooligosaccharide (COS) mixture was sufficient to reduce the E. coli initial population by at least 3 log cycles; COS never exhibited bactericidal action over S. aureus, unlike high and medium MW chitosans—which, at 0.5% (w/v), presented a bactericidal effect even against 107 cells/mL. When incorporated in liquid food matrices, medium and high MW chitosans maintained their activity, for both matrices and bacteria, although a slower activity was noticeable in milk; however, COS lost their activity upon both bacteria in milk after 4–8 h. Furthermore, addition of chitosans to apple juice led to several unpleasant off-flavors, such as astringency and after taste—which increased in magnitude with MW.
- Antimicrobial impact of essential oils on human skin colonizers and pathogens: targeting Staphylococcus speciesPublication . Lopes, Ana I.; Oliveira, Cláudia S.; Pintado, Manuela E.; Tavaria, Freni K.Background: Staphylococcus spp., one of the most abundant bacterial genera of the human skin microbiome, comprises commensal microorganisms – Staphylococcus epidermidis (S. epidermidis) – and opportunistic pathogens – Staphylococcus aureus (S. aureus). Staphylococcus-caused diseases are typically treated with antibiotics, but the antimicrobial resistance underscores the need for alternative treatments. Essential oils (EOs) are natural compounds made of terpenes and terpenoid molecules. Their antimicrobial activity results from the effect upon several cell targets, making the appearance of resistances unlikely. Objective: To study the antimicrobial activity of three EOs (eucalyptus, lavender, and thyme) on two Staphylococcus species (S. epidermidis and S. aureus). Methods: To assess the antimicrobial potential of EOs against the selected bacteria, the following assays were performed: i) determination of the minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations; ii) inhibition curves for each oil defined for the MIC, to understand how the bacteria respond to the oils; iii) antibiofilm formation assays using MIC, ½ MIC and ¼ MIC dilutions for each oil; and iv) evaluation of the membrane damage through flow cytometry, by staining the bacterial cells exposed to the oils, with propidium iodide (PI) and thiazole orange (TO). Results: The MIC and MBC values for the selected EOs ranged from 0.078% and 2.5% (v/v). Thyme presented the lower MIC for both bacteria. The inhibition curves corroborated the MIC results for all EOs. However, thyme was the one with a bactericidal effect on both bacteria. Thyme also presented higher antibiofilm activity compared to eucalyptus and lavender. The flow cytometry assay showed that all oils were able to damage the cell membrane of both bacteria (positive PI staining), but S. epidermidis showed less cell damage than S. aureus. Conclusion: The selected EOs presented antibacterial activity against S. epidermidis and S. aureus. Thyme EO was the one with the best antibacterial activity. S. epidermidis is more resistant to the oils than S. aureus.
- Antimicrobial impact of essential oils on human skin colonizers and pathogens: targeting Staphylococcus speciesPublication . Lopes, Ana I.; Oliveira, Cláudia S.; Pintado, Manuela E.; Tavaria, Freni K.Introduction: Staphylococcus spp. is one of the most abundant bacterial genera of the human skin microbiome (Joglekar et al. 2023). It comprises commensal microorganisms – Staphylococcus epidermidis (S. epidermidis) – and opportunistic pathogens – Staphylococcus aureus (S. aureus) (Imam and Luqman 2024). Staphylococci-caused diseases are typically treated with antibiotics, but the antimicrobial resistance underscores the need for alternative treatments. Essential oils (EOs) are natural compounds made of terpenes and terpenoid molecules. Their antimicrobial activity targets multiple cellular components, which reduces the likelihood of resistance development (Zuzarte et al. 2011). Objective: To study the antimicrobial activity of three EOs (eucalyptus, lavender, and thyme) on two Staphylococcus species (S. aureus and S. epidermidis). Conclusions: Eucalyptus, lavender, and thyme EOs present antibacterial activity against S. aureus and S. epidermidis. Thyme possesses the lowest MIC; the inhibition curves corroborated this result. The flow cytometry assay showed that all oils were able to damage bacterial cells; thyme oil presented the highest percentages of dead and injured cells. All EOs also showed anti-biofilm activity; thyme presented the highest anti-biofilm activity when compared to eucalyptus and lavender. S. epidermidis is more resistant to the oils than S. aureus.
- Antioxidant activity evaluation of fermentation distillation residuesPublication . Soares, Ana M. S.; Teixeira, Francisca S.; Pimentel, Lígia L.; Vidigal, Susana S. M. P.; Costa, Paula T.; Pintado, Manuela E.; Rodríguez-Alcalá, Luis M.Nature offers an unlimited variety of molecules with incredible biological activities, such as antioxidants among others, that are valuable for the maintenance of a good health by reducing the damage caused by oxidation [1,2]. This purpose allied to the richness of some wastes and by-products make distillation residues from industrial fermentation (FDRs) potential sources to obtain bioactive compounds. Accordingly the study for both its valorization and integration into a circular economy context was the aim of this work [3,4]. FDRs are known to be rich in several compounds such as phytosterols, triterpenes or fatty alcohols with potential biological activities [3,4]. Thus, two FDRs, from fermentation using sugarcane juice (FDR_SC) or very high polarity sugar (FDR_VHP) and respective extracts obtained by winterization with different solvents (ethanol (EtOH), acetone (AcO) and dichloromethane (DCM)) were used and the evaluation of its antioxidant activity were performed by DPPH, ABTS and ORAC assays. Inhibition percentage, IC 50, TEAC and ORAC Value parameters were determined. The results revealed great antioxidant potential for the studied FDRs, in particular for FDR_SC that had the best performance in most of the measured parameters. Also, the differences on solvents polarity used for the FDRs winterization had an important role in the antioxidant capacity results, which could be related to the selectivity to isolate different compounds.
- Antioxidant activity of chitooligosaccharides upon two biological systems: erythrocytes and bacteriophagesPublication . Fernandes, João C.; Eaton, Peter; Nascimento, Henrique; Gião, Maria S.; Ramos, Oscar. L.; Belo, Luís; Santos-Silva, Alice; Pintado, Manuela E.; Malcata, F. XavierMost of the reports to date on the antioxidant capacity of chitosans and chitooligosaccharides (COS) are based on strictly chemical methods. When studying antioxidants with potential in vivo applications, the method used to evaluate the antioxidant activity should be representative of the conditions in which the antioxidant might have a protective effect. In this work we evaluate the antioxidant activity of two COS mixtures and a low MW chitosan (LMWC) upon two biological oxidizable substrates – erythrocytes and phages, subjected to accelerated oxidation conditions. Our results suggest that COS/LMWC can be used as antioxidants in biological systems. All the tested compounds reduced either the hemolytic and DNA damage, by inhibiting H2O2- and AAPH-radicals. However, the results obtained for these biological assays did not reveal a dose dependence, contrary to the chemical assay, suggesting that the protective concentrations should be established, in order to prevent enhancement of the oxidative damage – i.e. a prooxidant effect.
- Antioxidant activity of sugar molasses, including protective effect against DNA oxidative damagePublication . Guimarães, Carla M.; Gião, Maria S.; Martinez, Sidónia S.; Pintado, Ana I. E.; Pintado, Manuela E.; Bento, Luís S.; Malcata, F. XavierExtracts were obtained from molasses, a byproduct of the sugar industry, via a number of chromatographic steps. Their antioxidant capacity was studied, including the inhibitory effect upon DNA oxidative damage;the phenolic compound profile there of was ascertained as well. Two extracts exhibited significant antioxidant features, expressed by their capacity to decolorize ABTS radical cation and to scavenge hydroxyl free radicals (via deoxyribose assay). Those 2 extracts also brought about protection against induced DNA oxidative damage (via decreasing DNA scission, as assessed by electrophoresis).The phenolic compounds syringic acid,p-hydroxybenzoic acid, vanillic acid, p-hydroxybenzaldehyde, and ferulic acid were positively identified and quantified.
- Antioxidant principles and volatile constituents from the north-western Iberian mint “erva-peixeira”, mentha cervinaPublication . Politi, Matteo; Rodrigues, César L.; Gião, Maria S.; Pintado, Manuela E.; Castro, Paula M. L.Total phenol content determined by the Folin–Ciocalteu assay and total antioxidant capacity measured by the ABTS•+ method were applied for the first time to analyze the aqueous extract prepared from the dried aerial parts of Mentha cervina, a Portuguese mint species traditionally used as a culinary herb in river fish-based dishes and currently commercialized to prepare digestive infusions. LC-MS/MS analysis was performed directly on the crude aqueous extract allowing the identification of seven phenolic compounds. The overall plant aroma was analyzed by the SPME/GC-MS method; this approach allowed the characterization of various constituents, as well as the comparison between the fresh and dried plant material. Such a comparison highlighted several metabolic changes that occur during the drying process of the aerial parts of this plant.