http://hdl.handle.net/10174/208 2026-04-04T05:34:39Z 2026-04-04T05:34:39Z Sebastiao, G. N. C. Alves-Pereira, I. Ferreira, R. M.A. http://hdl.handle.net/10174/39424 2025-10-16T09:54:57Z 2025-08-31T23:00:00Z

Title: Herbicide and Amino Acid Synergy: Effects on Yeast Stress Biomarkers Authors: Sebastiao, G. N. C.; Alves-Pereira, I.; Ferreira, R. M.A. Abstract: Employing biological models to study the combined effects of environmentally circulating xenobiotics offers a sustaina- ble approach to understanding their interaction mechanisms with living organisms. Although the use of atrazine (ATZ) and S-ethyl-N,N-dipropylthiocarbamate (EPTC) has been heavily restricted or not approved for agricultural crops in European Union member states, these herbicides remain widely used in several countries that export food to the EU. Furthermore, ATZ and EPTC residues remain elevated in European soil because of consecutive years of agronomic use. However, studies investigating their combined effects in eukaryotic systems are still limited. On the other hand, proline (Pro) protects living cells from stress by neutralizing reactive oxygen species (ROS), such as hydroxyl radical. This study aimed to assess the response of Saccharomy- ces cerevisiae, a unicellular eukaryotic organism, to individ- uals and combined exposures to EPTC, ATZ, and Pro, with particular emphasis on oxidative stress markers. Combined exposure to ATZ and EPTC triggered distinct responses in S. cerevisiae compared to individual treatments. Notably, it resulted in a decrease in total non-protein thiol content, glutathione (GSH) levels, and the activities of glutathione reductase (GR) and cytoplasmic catalase (Ctt), accompa- nied by an increase in ROS levels. These changes suggest that the dual exposure to EPTC and ATZ induced oxidative stress in S. cerevisiae, likely due to the decrease in the an- tioxidant activities of GR, which regenerates GSH, and Ctt, which scavenges hydrogen peroxide. The presence of Pro in the culture medium reversed the conditions of oxidative stress in terms of non-protein total thiols, ROS, and Ctt ac- tivity.

2025-08-31T23:00:00Z Teixeira, António P. S. Martins, M. Rosário Teixeira, Fátima C. Lopes, Daniela Parente, Helena http://hdl.handle.net/10174/24380 2019-01-31T11:09:58Z 2018-04-09T23:00:00Z

Title: Síntese de fosfonatos e avaliação da sua atividade anti-inflamatória e antioxidante Authors: Teixeira, António P. S.; Martins, M. Rosário; Teixeira, Fátima C.; Lopes, Daniela; Parente, Helena Abstract: Os fosfonatos são uma classe importante de compostos químicos, utilizados na terapia de patologias ósseas, tais como a doença de Paget, hipercalcémia e osteólise associada a tumores, devido à sua capacidade para inibir a perda óssea. Estes compostos têm também demonstrado atividade anticancerígena in vitro com inibição da proliferação celular de várias linhas tumorais [1,2]. Neste trabalho procedeu-se à síntese de ácidos fosfónicos e ésteres monofosfónicos, sintetizados a partir de aldeídos, bem como à avaliação da atividade antioxidante e da atividade anti-inflamatória dos compostos obtidos. A atividade antioxidante foi avaliada por três métodos diferentes, nomeadamente o método do radical DPPH, o sistema β-caroteno/ácido linoleico e o poder redutor total, com vista a inferir sobre o mecanismo de ação. Os estudos de atividade anti-inflamatória in vitro foram também avaliados por diferentes mecanismos de ação, com determinação da capacidade de inibição da desnaturação da albumina e de inibição da atividade de lipoxigenases. A toxidade dos fosfonatos em estudo foi avaliada utilizando o teste de letalidade em Artemia salina. Os compostos em estudo apresentaram atividade antioxidante, tendo-se observado que o composto (E)-3-(2-nitrofenil)-1-hidroxipropen-2-ilfosfonato de dimetilo foi o que apresentou melhor resultados na capacidade para sequestrar radicais, de poder redutor total, bem como na capacidade de proteção do substrato lipídico. Alguns dos compostos apresentaram também elevada capacidade anti-inflamatória, designadamente os ésteres 1-(4-bromofenil)-1-hidroximetilfosfonato de dimetilo e 1-(4-formilfenil)-1-hidroximetilfosfonato de metilo, os quais apresentaram elevado potencial para inibir a atividade da lipoxigenase.

2018-04-09T23:00:00Z Mendes, Paulo J. Pinto, Bebiana Garcia, M. Helena Valente, Andreia http://hdl.handle.net/10174/19854 2017-01-19T13:03:44Z 2016-01-01T00:00:00Z

Title: NEW METAL-BASED MICELLES AS ANTICANCER AGENTS Authors: Mendes, Paulo J.; Pinto, Bebiana; Garcia, M. Helena; Valente, Andreia Abstract: Cancer is a leader cause of death worldwide. One of the problems associated with the current chemotherapeutic options is the noxious side effects caused by the lack of selectivity. In this frame, our research group has been committed to the development of a new Ru and Fe macrometallodrugs.[1] The data obtained so far shows that these compounds present an intrinsic selectivity towards cancer cells (relatively to healthy cells) due to the incorporation of polymeric ligands that promote a passive targeting through the cancer cell membrane. These results prompted us to the development of new macrometallodrugs bearing bioessential metals such as Fe, Zn and Co. We used a ‘M(bipy) 3 ’ scaffold (bipy = 2,2’-bipyridine derivatives) for the synthesis of the new compounds due to the promising cytotoxicity results observed for related compounds.[2] As polymeric ligands we have chosen the polylactide-co-polyethylene glycol amphiphilic copolymer that is able to self-assemble into micelles in water, keeping the metal center hidden, like a Trojan horse. We will present the synthesis and characterization of the new compounds and some preliminary data on their ability to form stable micelles (Figure 1).

2016-01-01T00:00:00Z Mendes, Paulo J. Ramalho, João P. Prates Valente, Andreia Zinck, Philippe Nogueira, Guilherme Favrelle, Audrey http://hdl.handle.net/10174/19747 2017-01-12T16:44:51Z 2016-01-01T00:00:00Z

Title: DFT STUDIES ON THE MECHANISM OF RING-OPENING POLYMERIZATION OF LACTIDE WITH ADENINE Authors: Mendes, Paulo J.; Ramalho, João P. Prates; Valente, Andreia; Zinck, Philippe; Nogueira, Guilherme; Favrelle, Audrey Abstract: The use of organic molecules as catalysts for the ring-opening polymerization (ROP) of cyclic esters has gained much interest last years.[1] The use of a molecule of biological interest, able to initiate ROP of cyclic esters without any cocatalyst is even more interesting, as the resulting material will not contain any catalytic residue. Nucleobase-polymer conjugates development is thus an emerging area envisaging biomedical applications.[2] However, they are usually synthesized by tedious multistep procedures. Recently, adenine was used as organoinitiator for the ROP of L-lactide.[3] Reaction conditions involving short reaction times and relatively low temperatures enable the access to adenine-polylactide(Adn-PLA)conjugates in a simple one-step procedure, without additional catalyst and in the absence of solvent. In this study, computational investigations with density functional theory (DFT) were performed in order to clarify the reaction mechanism leading to the desired Adn-PLA. The results show that a hydrogen bond catalytic mechanism, involving a nucleophilic attack of the activated amine group of adenine onto the carbonyl group of lactide, seem to be plausible.

2016-01-01T00:00:00Z