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- On the valorization of Arbutus unedo L. Pomace: Polyphenol extraction and development of novel functional cookiesPublication . Duarte, Hugo; Carrera, Ceferino; Aliaño-González, M.J.; Gutiérrez-Escobar, Rocío; Jiménez-Hierro, María Jesús; Palma, Miguel; Galego, Ludovina; Romano, Anabela; Medronho, BrunoThe fruits of Arbutus unedo L. have a crimson colour and are enriched with remarkable concentrations of bioactive compounds such as anthocyanins and polyphenols. These fruits are commonly used in the production of a Portuguese Protected Geographical Indication distillate called “Aguardente de Medronho”. During this process, a solid pomace is generated and presently discarded without valuable applications. In this work, two strategies have been developed for the valorisation of A. unedo pomace. The first approach considers the extraction of polyphenols from this by-product through the optimization of an ultrasound-assisted method using a Box-Behnken design coupled with response surface methodology. The results indicate that the temperature and the percentage of methanol, along with their interaction, significantly influence the total concentration of polyphenols and the antioxidant activity of the extracts obtained. The optimal conditions identified consider the extraction of 0.5 g of sample with 20 mL of a solvent containing 74% MeOH (aq), at a pH of 4.8, maintained at 70 ◦C for 15 min. On the other hand, the second valorisation strategy considered the use of A. unedo pomace in the development of functional cookies. The incorporation of 15–20% pomace in the cookie formulation was well-received by consumers. This incorporation results in an intake of ca. 6.55 mg of polyphenols per gram of cookie consumed, accompanied by an antioxidant activity of 4.54 mg Trolox equivalents per gram of cookie consumed. Overall, these results encourage the employment of A. unedo pomace either as a reliable source of extracts enriched in polyphenols or as a nutraceutical active ingredient in functional cookies, thereby positively impacting human health.
- Engineering novel phenolic foams with lignin extracted from pine wood residues via a new levulinic-acid assisted processPublication . Melro, Elodie; Duarte, Hugo; Antunes, Filipe E.; Valente, Artur J.M.; Romano, Anabela; Norgren, Magnus; Medronho, BrunoPhenolic foams are typically produced from phenolic resins, using phenol and formaldehyde precursors. Therefore, common phenolic foams are non-sustainable, comprising growing environmental, health, and economic concerns. In this work, lignin extracted from pine wood residues using a "green" levulinic acid-based solvent, was used to partially substitute non-sustainable phenol. The novel engineered foams were systematically compared to foams composed of different types of commercially available technical lignins. Different features were analyzed, such as foam density, microstructure (electron microscopy), surface hydrophilicity (contact angle), chemical grafting (infrared spectroscopy) and mechanical and thermal features. Overall, it was observed that up to 30 wt% of phenol can be substituted by the new type of lignin, without compromising the foam properties. This work provides a new insights on the development of novel lignin-based foams as a very promising sustainable and renewable alternative to petrol-based counterparts.
- Poly(butylene succinate)-based composites with technical and extracted lignins from wood residuesPublication . Melro, Elodie; Duarte, Hugo; Eivazi, Alireza; Costa, Carolina; Faleiro, Maria Leonor; Rosa Da Costa, Ana; Antunes, Filipe E.; Valente, Artur J. M.; Romano, Anabela; Norgren, Magnus; Medronho, BrunoPoly(butylene succinate) (PBS) has been drawing attention as a reliable biodegradable and sustainable alternative to synthetic petroleum-based polymers. In this study, PBS-lignin composites were developed using a recently extracted lignin (LA-lignin) from pine wood residues employing an innovative sustainable approach. These composites were systematically compared with PBS-based composites formed with commonly used technical lignins. The molecular weight of the lignins was evaluated, along with various structural and performance-related properties. The LA-lignin/PBS composites display a remarkably low water solubility (ca. < 2%), water uptake (ca. 100 degrees). Moreover, the rigidity and thermal stability of the LA-lignin-PBS composites were higher than those of the systems formed with technical lignins. Although all composites studied present remarkable antioxidant features, the novel LA-lignin-PBS systems stand out in terms of antiadhesion activity against both Gram-positive and Gram-negative bacteria. Overall, the systematic analysis performed in this work regarding the impact of various lignins on the formed PBS composites enables a better understanding of the essential structural and compositional lignin features for achieving biobased materials with superior properties.
- Response of thymus lotocephalus in vitro cultures to drought stress and role of green extracts in cosmeticsPublication . Mansinhos, Inês; Gonçalves, Sandra; Rodríguez-Solana, Raquel; Duarte, Hugo; Ordóñez-Díaz, José Luis; Moreno-Rojas, José Manuel; Romano, AnabelaThe impact of drought stress induced by polyethylene glycol (PEG) on morphological, physiological, (bio)chemical, and biological characteristics of Thymus lotocephalus López and Morales shoot cultures have been investigated, as well as the potential of iron oxide nanoparticles, salicylic acid, and methyl jasmonate (MeJA) as alleviating drought stress agents. Results showed that PEG caused oxidative stress in a dose-dependent manner, raising H2O2 levels and reducing shoots’ growth, photosynthetic pigment contents, and phenolic compounds production, especially phenolic acids, including the major compound rosmarinic acid. Moreover, Fourier Transform Infrared Spectra analysis revealed that PEG treatment caused changes in shoots’ composition, enhancing terpenoids biosynthesis. PEG also decreased the biological activities (antioxidant, anti-tyrosinase, and photoprotective) of the eco-friendly extracts obtained with a Natural Deep Eutectic Solvent. MeJA was the most efficient agent in protecting cells from oxidative damage caused by drought, by improving the biosynthesis of phenolics, like methyl 6-O-galloyl-β-D-glucopyranoside and salvianolic acids, as well as improving the extracts’ antioxidant activity. Altogether, the obtained results demonstrated a negative impact of PEG on T. lotocephalus shoots and an effective role of MeJA as a mitigating agent of drought stress. Additionally, extracts showed a good potential to be used in the cosmetics industry as skincare products.
- On the development of Phenol-Formaldehyde resins using a new type of lignin extracted from pine wood with a Levulinic-Acid based solventPublication . Melro, Elodie; Antunes, Filipe E.; Valente, Artur J. M.; Duarte, Hugo; Romano, A.; Medronho, BrunoResole resins have many applications, especially for foam production. However, the use of phenol, a key ingredient in resoles, has serious environmental and economic disadvantages. In this work, lignin extracted from pine wood using a “green” solvent, levulinic acid, was used to partially replace the non-sustainable phenol. The physicochemical properties of this novel resin were compared with resins composed of different types of commercial lignins. All resins were optimized to keep their free formaldehyde content below 1 wt%, by carefully adjusting the pH of the mixture. Substitution of phenol with lignin generally increases the viscosity of the resins, which is further increased with the lignin mass fraction. The addition of lignin decreases the kinetics of gelification of the resin. The type and amount of lignin also affect the thermal stability of the resins. It was possible to obtain resins with higher thermal stability than the standard phenol-formaldehyde resins without lignin. This work provides new insights regarding the development of lignin-based resoles as a very promising sustainable alternative to petrol-based resins.
- Ultra-/Small angle X-ray scattering (USAXS/SAXS) and static light scattering (SLS) modeling as a tool to determine structural changes and effect on growth in S. epidermidisPublication . Duarte, Hugo; Gummel, Jeremie; Robles, Eric; Berti, Debora; Fratini, EmilianoUsually, to characterize bacterial cells' susceptibility to antimicrobials, basic microbiology techniques such as serial dilutions or disk assays are used. In this work, we present an approach focused on combining static light scattering (SLS) and ultra-/ small angle X-ray scattering (USAXS/SAXS). This approach was used to support microbiology techniques, with the aim of understanding the structural changes caused to bacteria when they are exposed to different stresses like pH, oxidation, and surfactants. Using USAXS/SAXS and SLS data, we developed a detailed multiscale model for a Gram-positive bacterium, S. epidermidis, and we extracted information regarding changes in the overall size and cell thickness induced by different stresses (i.e., pH and hydrogen peroxide). Increasing the concentration of hydrogen peroxide leads to a progressive reduction in cell wall thickness. Moreover, the concomitant use of pH and hydrogen peroxide provides evidence for a synergy in inhibiting the S. epidermidis growth. These promising results will be used as a starting base to further investigate more complex formulations and improve/refine the data modeling of bacteria in the small angle scattering regime.
- Probing cellulose–solvent interactions with self-diffusion NMR: Onium hydroxide concentration and co-solvent effectsPublication . Medronho, Bruno; Pereira, Ana; Duarte, Hugo; Gentile, L.; Rosa Da Costa, Ana; Romano, A; Olsson, U.The molecular self-diffusion coefficients were accessed, for the first time, in solutions of microcrystalline cel-lulose, dissolved in 30 wt% and 55 wt% aqueous tetrabutylammonium hydroxide, TBAH (aq), and in mixtures of 40 wt% TBAH (aq) with an organic co-solvent, dimethylsulfoxide (DMSO), through pulsed field gradient stim-ulated echo NMR measurements. A two-state model was applied to estimate alpha (i.e., average number of ions that "bind" to each anhydroglucose unit) and Pb (i.e., fraction of "bound" molecules of DMSO, TBAH or H2O to cellulose) parameters. The alpha values suggest that TBA+ ions can bind to cellulose within 0.5 TBA+ to 2.3 TBA+/ AGU. On the other hand, the Pb parameter increases when raising cellulose concentration for TBA+, DMSO and water in all solvent systems. Data suggests that TBAH interacts with the ionized OH groups from cellulose forming a sheath of bulky TBA+ counterions which consequently leads to steric hindrance between cellulose chains.
- Sustainable extraction of polyphenols from vine shoots using deep eutectic solvents: influence of the solvent, vitis sp., and extraction techniquePublication . Duarte, Hugo; Aliaño-González, María José; Cantos-Villar, Emma; Faleiro, Leonor; Romano, Anabela; Medronho, BrunoVine shoots are the main by-products of grapevine pruning with no added value. In the present study, deep eutectic solvents (DESs) were used as alternatives to traditional chemical solvents, for the extraction of phyto chemicals from grapevine shoots. Three levulinic acid-based DESs were tested for the first time, and their per formance was compared to methanol (a standard chemical solvent) regarding the extraction of phenolic compounds from thirteen Vitis sp. shoots. Two extraction methods have been applied: ultrasound-assisted extraction and solid-liquid extraction. A total of eleven polyphenols which belongs to four families (proantho cyanins, stilbenes, hydroxycinnamic acids, and flavonols) have been identified and quantified in the extracts. The statistical analysis shows that the levulinic acid-based DES systems are novel and important alternatives to chemical solvents due to favourable eco-friendly properties and remarkable extraction performance of poly phenols. On the other hand, the ultrasound-assisted extraction technique has significantly increased the extraction rate in comparison to the solid-liquid extraction method with p-values lower than 0.05 for most compounds. The genetic factor has been shown to play an important role in the content of extracted polyphenols, being V. riparia pubescente the one that presented the highest concentrations of extracted polyphenols. Finally, the polyphenol-enriched extracts have proven important properties such as antioxidant activity and significant delay in bacteria growth against both gram-positive and gram-negative bacteria. It is important to note that, to the best of our knowledge, this is the first time that deep eutectic solvents have been used for the extraction of bioactive compounds from vine shoot residues.
- Advancements in detection and mitigation strategies for Petroleum-Derived contaminants in aquatic environments: a comprehensive reviewPublication . Duarte, Hugo; Aliaño González, María José; Medronho, BrunoThe exponential increase in the production and transportation of petroleum-derived products observed in recent years has been driven by the escalating demand for energy, textiles, plastic-based materials, and other goods derived from petroleum. Consequently, there has been a corresponding rise in spills of these petroleum derivatives, particularly in water sources utilized for transportation or, occasionally, illegally utilized for tank cleaning or industrial equipment maintenance. Numerous researchers have proposed highly effective techniques for detecting these products, aiming to facilitate their cleanup or containment and thereby minimize environmental pollution. However, many of these techniques rely on the identification of individual compounds, which presents significant drawbacks, including complexity of handling, subjectivity, lengthy analysis times, infeasibility for in situ analysis, and high costs. In response, there has been a notable surge in the utilization of sensors or generalized profiling techniques serving as sensors to generate characteristic fingerprints of these products, thereby circumventing the aforementioned disadvantages. This review comprehensively examines the evolution of techniques employed for detecting petroleum-derived products in water samples, along with their associated advantages and disadvantages. Furthermore, the review examines current perspectives on methods for the removal and/or containment of these products from water sources, to minimize their environmental impact and the associated health repercussions on living organisms and ecosystems.
- On the valorization of olive oil pomace: a sustainable approach for methylene blue removal from aqueous mediaPublication . saoudi hassani, el mokhtar; Duarte, Hugo; Brás, João; Taleb, Abdeslam; Taleb, Mustapha; Rais, Zakia; Eivazi, Alireza; Norgren, Magnus; Romano, Anabela; Medronho, BrunoCurrently, industrial water pollution represents a significant global challenge, with the potential to adversely impact human health and the integrity of ecosystems. The continuous increase in global consumption has resulted in an exponential rise in the use of dyes, which have become one of the major water pollutants, causing significant environmental impacts. In order to address these concerns, a number of wastewater treatment methods have been developed, with a particular focus on physicochemical approaches, such as adsorption. The objective of this study is to investigate the potential of a bio-based material derived from olive oil pomace (OOP) as an environmentally friendly bio-adsorbent for the removal of methylene blue (MB), a cationic dye commonly found in textile effluents. The biobased material was initially characterized by determining the point of zero charge (pHpzc) and using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Subsequently, a comprehensive analysis was conducted, evaluating the impact of specific physicochemical parameters on MB adsorption, which included a thorough examination of the kinetic and thermodynamic aspects. The adsorption process was characterized using Langmuir, Freundlich, Brunauer-Emmett-Teller (BET), and Dubinin Radushkevich (D-R) isotherms. The results suggest that the equilibrium of adsorption is achieved within ca. 200 min, following pseudo-second-order kinetics. The optimal conditions, including adsorbent mass, temperature, bulk pH, and dye concentration, yielded a maximum adsorption capacity of ca. 93% (i.e., 428 mg g−1) for a pomace concentration of 450 mg L−1. The results suggest a monolayer adsorption process with preferential electrostatic interactions between the dye and the pomace adsorbent. This is supported by the application of Langmuir, BET, Freundlich, and D-R isotherm models. The thermodynamic analysis indicates that the adsorption process is spontaneous and exothermic. This work presents a sustainable solution for mitigating MB contamination in wastewater streams while simultaneously valorizing OOP, an agricultural by-product that presents risks to human health and the environment. In conclusion, this approach offers an innovative ecological alternative to synthetic adsorbents.