Browsing by Issue Date, starting with "2015-09-25"
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- Optimizing physicochemical properties of naturalantioxidants and geroprotectors: L-carnosine and melatoninPublication . Shemchuk, Oleksii; Grepioni, Fabrizia; Duarte, TeresaThe issue of “Healthy Ageing” has become a significant challenge due to the continuous grow of World Population Ageing. Advancing health and well-being into old age and ensuring supportive environments is a main objective of NATO’s Department of Economic and Social Affairs Population Division [1]. Natural antioxidants such as L-carnosine and melatonin have been successfully used as geroprotectors. They reduce the risk of developing ageing-related diseases which is one the main aspects of healthy ageing. New formulation of the existing APIs is a widely used approach to optimize their physicochemical properties. Carnosine underwent reactions with a number of organic acids resulting in the discovery of seven new salts. The obtained salts were characterized by X-ray powder diffraction and thermal analyses. The structures were determined using X-ray Powder Diffraction (XRPD). The carnosine salts with glycolic and succinic acids might be of higher interest since both components possess antioxidant activity and carnosine, when used as a nutraceutical is usually combined with other antioxidants. Thus, the new formulation of carnosine as a salt with an acid possessing antioxidant activity can enhance its biological activity. Melatonin was co-crystallized with a number of coformers from various chemical groups. Two new co-crystals of melatonin with DABCO and piperazine were obtained by using mechanochemical technique (kneading). The structure of melatonin-DABCO co-crystal was established from a single crystal obtained by recrystallization from dichloromethane. The structure of melatonin-piperazine was solved using XRPD. Though only one of the obtained co-crystals can find a direct application in Pharmaceutical industry (DABCO does not belong to the GRAS list), our results confirm the reactivity of melatonin in co-crystallization processes, and emphasizes the need to continue the search for an improved formulation.
- Estratégias para o aumento do rendimento em biomassa e lípidos na levedura Rhodosporidium toruloidesPublication . Martins, Laura Isabel Tangerino; Raposo, Sara; Costa, Maria Emília LimaEsta dissertação focou-se na otimização das condições de crescimento e de acumulação de lípidos pela levedura R. toruloides CECT 1499, usando resíduos de alfarroba como fonte de carbono, como uma alternativa mais sustentável para a produção de biodiesel de segunda geração. Estudos iniciais revelaram que o melhor meio YPD para a produção de biomassa no inóculo é o meio constituído por 15 g/L de açúcares de alfarroba, com uma biomassa máxima de 9,22 g/L. De seguida foram testados diferentes rácios C/N, em o rácio C/N 330, com 70 g/L de açúcares e 0,1 g/L de sulfato de amónio apresentou os melhores resultados. Avaliou-se o efeito do arejamento na produção de biomassa e lípidos, verificando-se que o caudal de arejamento de 0,3 vvm é insuficiente para induzir o metabolismo lipídico, havendo apenas produção de biomassa. Com o caudal de arejamento de 0,75 vvm já foi possível chegar a uma concentração de lípidos de 1,25 g/L. De modo a aumentar a produção de lípidos e biomassa avaliou-se o efeito do uso de n-dodecano. A adição de 1 % (v/v) de n-dodecano melhora as condições de transferência de massa, aumentando cerca de 20 % o valor de KLa do meio. O uso do vetor aumentou a concentração de lípidos de para 2,57 g/L e o rendimento lipídico sofreu um incremento para 33 % (p/p). Foi ainda feito um ensaio em modo fed-batch, conseguindo-se produzir elevadas quantidades de biomassa, 25,23 g/L e uma concentração de lípidos de 1,40 g/L. Contudo esta produção lipídica foi inferior, à obtida em batch com adição do vetor e com idêntico caudal de arejamento, sugerindo que neste caso o arejamento foi insuficiente para induzir acumulação de lípidos. O estudo do perfil em ácidos gordos sugere que o óleo produzido pela levedura R. toruloides, usando a alfarroba como fonte de carbono, é adequado para a produção de biodiesel de segunda geração.
- Biomaterials from renewable sources: biosurfactants and biopolymersPublication . Ajao, Victor Olusola; Galletti, PaolaSurfactants are a wide class of compounds used in a broad spectrum of household and industrial applications. However, two of their main concerns lie in their non-biodegradability and the fact that they are low-dose permanent toxicants in the water ecosystem, arising from the widespread usage. An aspect of this thesis involves the synthesis and biodegradability assessment of a new family of biobased surfactants that could be potential green alternatives to traditional anionic and non-ionic surfactants (e.g. alkylphenol ethoxylate, APE). They were prepared from itaconic acid and fatty amines (molecules industrially obtained from renewable resources) under mild conditions (solventless) and in excellent yields. Biodegradability tests confirmed that many of them are biodegradable. The second part of this thesis is focused on the production of polyhydroxyalkanoates (PHAs) from organic renewable resources: paper wastes and microalgae. PHAs are biodegradable, immunological inert and very versatile bioplastics with properties similar to worldwide used petro-based plastics. They have broad applications in many industrial fields: pharma and biomedical, food and beverage packaging, fibres, electronics and automobiles. Recent research on PHAs has focused on developing cost-effective production using low-value or industrial waste as carbon source for PHA-producing bacteria. In this study, pyrolysis oil from paper waste (bio-oil) and aqueous phase obtained from hydrothermal liquefaction of two microalgae species (Scenedesmus almeriensis and Nannochloropsis gaditana) were investigated as substrates for microbial conversions with the aim of PHA production. Both substrates were first upgraded via acidogenic fermentation to obtain liquid streams enriched with volatile fatty acids (VFAs, which are considered excellent platforms for PHA production) and di/triethylcitrates (DEC and TEC, which are value-added chemicals with wide range of applications, e.g. plasticizers). After this step, acidogenic products were extracted and used for PHA production in a subsequent aerobic fermentation.
- Structure, dynamics, and substituent effects of sulfa-drugs and their model compounds by free jet rotational spectroscopy and model calculationsPublication . Nonato, Maybel; Melandri, Sonia; Maris, AssimoSulfa-drug derivatives, such as Benzenesulfonamide (BSA), para-Toluenesulfonamide (p-TSA), ortho-Toluenesulfonamide (o-TSA), and Sulfanilamide (SAM), are widely used in the chemical industry. However, these polar organic compounds constitute emerging environmental concerns. Unfortunately, there is lack of eco-toxicological data for these substances but some insight can be obtained by analyzing the molecular structure and conformational properties of the compounds which can aid with the understanding of their biological mechanisms. Rotational spectroscopy coupled with high level theoretical calculations can supply these data. In this dissertation, the structural information and conformational properties of the sulfa-drug derivatives were obtained by a combined study of rotational spectroscopy in free jet expansions and quantum chemical calculations (B3LYP and MP2 at 6-311++G** level of theory). The effect of the added substituents (ortho/para-CH3 and para-NH2), in terms of structural parameters, were investigated as well since BSA is the molecular backbone of o-TSA, p-TSA, and SAM. Results showed that the four sulfa-drug derivatives favour the eclipsed conformation of the –NH2 and –SO2 groups but rationalization behind this preference varies among the compounds. Conversely, addition of –CH3 and –NH2 in the para position has no significant effects on the structural parameters of BSA but addition of ortho-CH3 brought some dramatic changes in the bond angles.