Centro de Química Estrutural

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Publications

Natural organic matter dynamics in permafrost peatlands: critical overview of recent findings and characterization tools

Publication . Folhas, Diogo; Couture, Raoul-Marie; Laurion, Isabelle; Vieira, Gonçalo; Canário, João

Rising temperatures are destabilizing permafrost in northern latitudes, leading to the mobilization, transformation and cycling of natural organic matter (NOM), nutrients, and contaminants into newly formed aquatic systems. Analyzing the chemical composition of organic matter is crucial for understanding the biogeochemical processes at play. Furthermore, it is essential to investigate how seasonal variations and anoxic conditions influence these processes, as well as their effects on microbial activity and NOM composition. This review provides an overview of northern peatlands, terminal electron acceptor species, and key analytical techniques used to characterize organic matter: UV/Vis and Fluorescence Spectroscopy, FTIR, FT-ICR-MS, and Nuclear Magnetic Resonance. Rather than focusing on the theoretical aspects of these techniques, we emphasize the type of information they offer about NOM and how to interpret these data within the context of biogeochemical transformations in permafrost-affected systems.

2025Journal article

Open access

Chemical Profile and Biological Activities of Brassica rapa and Brassica napus Ex Situ Collection from Portugal

Publication . Serrano, Carmo; Oliveira, M. Conceição; Lopes, V. R.; Soares, Andreia; Molina, Adriana K.; Paschoalinotto, Beatriz H.; Pires, Tânia C. S. P.; Serra, Octávio; Barata, Ana M.

This study aimed to analyse the chemical profile and biological activities of 29 accessions of Brassica rapa (turnips) and 9 of Brassica napus (turnips and seeds) collections, maintained ex situ in Por- tugal. HPLC-HRMS allowed the determination of glucosinolates (GLS) and polyphenolic compounds. The antioxidant and antimicrobial activities were determined by using relevant assays. The chemical profiles showed that glucosamine, gluconasturtiin, and neoglucobrassin were the most abundant GLS in the extracts from the turnip accessions. Minor forms of GLS include gluconapoleiferin, glucobrassicanapin, glucoerucin, glucobrassin, and 4-hydroxyglucobrassin. Both species exhibited strong antioxidant activity, attributed to glucosinolates and phenolic compounds. The methanol extracts of Brassica rapa accessions were assessed against a panel of five Gram-negative bacteria (Enterobacter cloacae, Escherichia coli, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serovar, and Yersinia enterocolitica) and three Gram-positive bacteria (Bacillus cereus, Listeria monocytogenes, and Staphylococcus aureus). The extracts exhibited activity against S. enterica and S. aureus, and two showed inhibitory activity against E. coli and Y. enterocolitica. This study provides valuable insights into the chemical composition and biological properties of Brassica rapa and Brassica napus collections in Portugal. The selected accessions can constitute potential sources of natural antioxidants and bioactive compounds, which can be used in breeding programs and improving human health and to promote healthy food systems.

2024-04Journal article

Open access

Coumarins in spirit beverages: sources, quantification, and their involvement in quality, authenticity and food safety

Publication . Oliveira-Alves, Sheila; Lourenço, Sílvia; Fernandes, Tiago A.; Canas, Sara

This comprehensive review is devoted to an under-exploited family of phenolic compounds, the coumarins, and the most relevant strands in which they are involved in some spirit beverages— wine spirit, brandy, whiskey, sugar-cane spirits (rum and cachaça) and grape marc spirit—with great importance worldwide in terms of production, trade and consumption. It gathers the key discoveries on the topic, considering the production process of each spirit beverage, and the related sources of coumarins (different kinds of wood used in the ageing stage), along with the factors that govern them and can influence the sensory properties of the aged beverages. An overview of the analytical methods available for their identification/quantification is also included, as well as the corresponding trends for the advancement of knowledge in this field. Moreover, the remarkable role of coumarins as nutraceuticals, their importance as chemical markers for authenticity purposes, and their relationship with the food safety of these spirit beverages are also addressed, highlighting the current gaps and issues, and providing clues for future research.

2024-01Journal article

Open access

Optimized metrological and geochemical assessment of trends in estuarine and oceanic systems

Publication . Borges, Carlos; Silva, Ricardo Jorge Neves Bettencourt da; Palma, Carla Maria Ferreira Mesquita

The evaluation of the environmental status and evolution of an ecosystem is a crucial element to support decision-makers in their management. Such evaluation must incorporate the uncertainty of collected information to allow their objective and binding interpretation. However, up to now, there were no tools for the objective interpretation of environmental monitoring data that consider system heterogeneity and the impact of the sampling strategy in system characterization, making these monitoring inefficient. The main goal of this work was to produce tools, implemented in user-friendly software, for the objective assessment of the status, trends and correlations of relevant parameters of vast environmental areas, to produce biding information for the management of these resources. The Monte Carlo Method simulation of the spatial distribution of studied parameters considering sampling positioning and sample analysis uncertainty, and conservative interpolation of information between sampling points, allowed simulating mean compositional values, trends and correlations with known uncertainty. This tool was applied to study a large estuarine system from the Tagus River and an even larger coastal area from the Portuguese Continental Platform. The developed tool was successfully applied to study nutrients and characteristic oceanographic features in the oceanic area. The tool was developed for areas monitored from up to 100 points using prior information from studied quantities while keeping the studied parameter’s correlation. The application of the developed tools to the above-mentioned systems in different seasonal conditions allowed the objective and metrologically sound evaluation of trends and correlations of studied parameters. This work aims to change the paradigm of probably the most demanding analytical challenge, the monitoring of vast environmental areas, contributing to the objectivity ambitioned for these studies.

2025-01-23Doctoral thesis

Open access

First report on the synergistic interaction between essential oils against the pinewood nematode Bursaphelenchus xylophilus

Publication . Faria, Jorge M. S.; Cavaco, Tomás; Gonçalves, Diogo; Barbosa, Pedro; Teixeira, Dora Martins; Moiteiro, Cristina; Inácio, Maria L.

Control of the pinewood nematode (PWN), the causal agent of pine wilt disease, can be achieved through the trunk injection of nematicides; however, many pesticides have been linked to environmental and human health concerns. Essential oils (EOs) are suitable alternatives due to their biodegradability and low toxicity to mammals. These complex mixtures of plant volatiles often display multiple biological activities and synergistic interactions between their compounds. The present work profiled the toxicity of eight EOs against the PWN in comparison to their 1:1 mixtures, to screen for successful synergistic interactions. Additionally, the main compounds of the most synergistic mixtures were characterized for their predicted environmental fate and toxicity to mammals in comparison to emamectin benzoate, a commercial nematicide used against PWN. The mixtures of Cymbopogon citratus with Mentha piperita and of Foeniculum vulgare with Satureja montana EOs showed the highest activities, with half-maximal effective concentrations (EC50) of 0.09 and 0.05 L/mL, respectively. For these, complete PWN mortality was reached after only ca. 15 min or 2 h of direct contact, respectively. Their major compounds had a higher predicted affinity to air and water environmental compartments and are reported to have very low toxicity to mammals, with low acute oral and dermal toxicities. In comparison, emamectin benzoate showed lower nematicidal activity, a higher affinity to the soil and sediments environmental compartments and higher reported oral and dermal toxicity to mammals. Overall, uncovering synergistic activities in combinations of EOs from plants of different families may prove to be a source of biopesticides with optimized toxicity against PWNs.

2023-06Journal article

Open access