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- Molybdenum(VI) complexes with ligands derived from 5-(2-pyridyl)-2H-tetrazole as catalysts for the epoxidation of olefinsPublication . Nunes, Martinique S.; Gomes, Ana C.; Neves, Patrícia; Mendes, Ricardo F.; Almeida Paz, Filipe A.; Lopes, André; Pillinger, Martyn; Gonçalves, Isabel S.; Valente, Anabela A.The development of effective catalytic epoxidation processes that are an alternative to stoichiometric non-selective oxidation routes is important to meet environmental sustainability goals. In this work, molybdenum (VI) compounds bearing 5-(2-pyridyl)-2H-tetrazole derivatives as organic components, namely the ionic and neutral mononuclear complexes (H2ptz)[MoO2Cl2(ptz)] (1) and [MoO2Cl2(tBu-ptz)] (2), and the new Lindqvist-type polyoxometalate (POM) [tBu-Hptz]2[Mo6O19] (3), where Hptz = 5-(2-pyridyl)tetrazole and tBu-ptz = 2-tert- butyl-5-(2-pyridyl)- 2H-tetrazole, were studied as epoxidation catalysts using readily available and relatively ecofriendly hydroperoxide oxidants, namely hydrogen peroxide and tert-butyl hydroperoxide (TBHP). The pre-pared catalysts were very active. For example, 100% cis-cyclooctene conversion and 100% epoxide selectivity were reached at 1 h for 1 and 3, and 10 min for 2 (with TBHP). Catalytic and characterization studies indicated that the mononuclear complexes suffered chemical transformations under the reaction conditions, whereas 3 was structurally stable. This POM acted as a homogeneous catalyst and could be recycled by employing an ionic liquid solvent. The POM can be synthesized from 2 under different conditions, including those used in the catalytic process. Moreover, 3 was an effective epoxidation catalyst for a biobased substrate scope that included fatty acid methyl esters and the terpene dl-limonene.
- Effects of dietary curcumin in growth performance, oxidative status and gut morphometry and function of gilthead seabream postlarvaePublication . Xavier, Maria João; Navarro-Guillén, Carmen; Lopes, André; Colen, R.; Teodósio, Rita; Mendes, Rodrigo; Oliveira, Beatriz; Valente, Luisa M.P.; Conceição, Luís E.C.; Engrola, SofiaAn imbalance in the production and detoxification of reactive oxygen species and other oxidants can disrupt a l l types of cellular compounds, and lead to a state of oxidative stress. Preventing this state is essential to improve growth and health in animal production. Therefore, the aim of this work was to assess i f the dieta r y supple-mentation of curcumin cou l d improve the antioxidant status and intestine structu r e and functionalit y of gilthead seabream postlarvae, with the global objective of improving fish growth performance and robustness. Two experimental diets supplemented with different doses of curcumin (LOW and HIGH diets), and a commercial diet were fed to quadruplicate groups of postlarvae, for 20 days. At the end of the feeding trial fish fed the supple-mented diets significantly improved their antioxidant status compared to CTRL fed fish. LOW and HIGH fed fish presented lower protein oxidative damage (P < 0.05) and higher total antioxidant capacity (P < 0.05). Moreover, postlarvae fed curcumin supplemented diets also presented an upregulation of nuclear factor erythroid 2 - related factor 2 (nrf2) and glutathione-disulfide reductase (gr) in HIGH (P < 0.05) and heat shock protein 70 (hsp70) in LOW treatments (P < 0.05). No differences were observed in growth performance, intestine morphome t r y , and digestive enzymes activities among treatments (P > 0.05). In conclusion, dieta r y curcumin supplementation was able to enhance gilthead seabream postlarvae robustness through a modulation of the oxidative status, increasing total antioxidant capacity and decreasing protein oxidative damage. This data pro-vide evidence that curcumin can be a suitable feed additive to promote heath status and robustness of fish at early stages of development, therefore contributing for the development and sustainabilit y of marine fish hatchery production.
- Exploring the potential of wine industry by-products as source of additives to improve the quality of aquafeedPublication . Camara, Jose S.; Lourenco, Silvia; Silva, Catarina; Lopes, André; Andrade, Carlos; Perestrelo, RosaThe recent growing concern driven by consumer interest in the safety and quality of seafood, has boosted the search for healthy and functional aquafeeds. The current study represents the first approach to assess the potential of volatile composition of the wine industry by products (e.g., grape pomace, grape stems, lees), as additives for improving the quality of fish feeds in terms of organoleptic characteristics (e.g., aroma and flavor) and health benefits. Headspace solid-phase microextraction followed by gas chromatography-mass spectrometry (HS-SPME/GC-MS) was used to establish the volatile profile of wine industry by-products. A total of 153 volatile organic compounds (VOCs), which belong to different chemical families, comprising 36 esters, 31 carbonyl compound, 20 alcohols, 18 terpenoids, 17 acids, 11 furanic compounds, four volatile phenols, two lactones, and 14 miscellaneous, were identified. Esters and terpenoids showed a positive contribution to the aquafeeds aroma with fruity, sweet, green, fresh, and berry notes, whereas some acids (e.g., hexanoic acid) and terpenoids (e.g., limonene) could be used as antimicrobial, antioxidant and antiproliferative agents. Our findings confirmed the potential of wine industry by-products as a rich source of essential compounds to enhance the quality of aquafeeds towards the valorization of winery waste based on the concept of circular economy. Further investigation on the extraction, isolation and purification of VOCs from a natural bio-source will guarantee the safety of the aquafeed and compliance with the requirements of the animal feed industry.