Associated Laboratory for Green Chemistry - Clean Technologies and Processes

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Publications

Potential of marine macroalgae as a source of iodine and natural antioxidants: their use in inhibiting lipid peroxidation reactions in food products

Publication . Santos, Francisca Filipa Pereira Leite dos; Soares, Cristina Maria Dias

The deterioration of food quality due to lipid peroxidation poses a significant challenge in the food industry. This study evaluates the effectiveness of seaweed extracts as natural antioxidants in preventing lipid oxidation during the accelerated ageing of oils used in canned fish. Ten seaweeds were selected: four brown (Fucus vesiculosus, Himanthalia elongata, Eisenia bicyclis, and Undaria pinnatifida); two green (Ulva Lactuca, and Codium tomentosum); and 4 red (Palmaria palmata, Gracilaria gracilis, Chondrus cripus, and Porphyra dioica). Solid-liquid extraction (SLE) was used to optimize extraction conditions, followed by subcritical water extraction (SWE) at 140°C and 190°C, and ultrasound-assisted extraction (UAE) for 10 and 20 minutes. The extracts were analyzed for phenolic compounds and antioxidant capacity. Olive and sunflower oils were tested for lipid oxidation and accelerated ageing tests were conducted on sunflower oil with the seaweed extracts. The results were compared to a control and BHTtreated oil. Brown seaweeds consistently showed the best antioxidant performance, significantly reducing lipid oxidation, while red seaweeds were less effective. Sensory analysis indicated less rancidity in oils treated with brown macroalgae. These findings suggest that brown seaweeds have strong potential as natural antioxidants, offering a possible replacement for synthetic antioxidants in food preservation. Further research is needed to optimize extract concentration, assess nutritional impacts, and examine long-term effects on the shelf life of canned fish.

2024-10-16Master thesis

Embargoed access

Comparative studies on the photoreactivity, efficacy, and safety of depigmenting agents

Publication . Mota, Sandra; Rosa, Gonçalo P.; Barreto, Maria Carmo; Garrido, Jorge; Sousa, Emília; Cruz, Maria T.; Almeida, Isabel F.; Quintas, Clara

Depigmenting products are increasingly used to counteract skin hyperpigmentation and related psychosocial issues. This study aimed to compare different depigmenting agents—4-butylresorcinol; bakuchiol; tranexamic acid; ascorbyl glucoside; α-arbutin; and ascorbic acid—for photoreactivity; tyrosinase inhibition; and safety. Photoreactivity was assessed using the Reactive Oxygen Species assay. In vitro tyrosinase inhibition was compared, and cell viability was assessed in B-16V melanocytes to evaluate safety. Results showed 4-butylresorcinol, ascorbyl glucoside, and α-arbutin are non-photoreactive, while for ascorbic acid and bakuchiol it was not possible to reach conclusive results due to the lack of specificity of the ROS assay. 4-Butylresorcinol, acting as a competitive inhibitor, displayed potent tyrosinase inhibition, followed by ascorbic acid and bakuchiol. Both 4-butylresorcinol and bakuchiol reduced cell viability in a concentration-dependent manner. The insights obtained in this work support the development of depigmenting products by providing useful scientific guidance on the photostability, tyrosinase inhibitory efficacy, and skin safety of depigmenting agents.

2023Journal article

Open access

Recent advances in biological properties of brown algae-derived compounds for nutraceutical applications

Publication . Silva, Aurora; Cassani, Lucia; Grosso, Clara; Garcia-Oliveira, Paula; Morais, Stephanie; Echave, Javier; Carpena, Maria; Xiao, Jianbo; Barroso, M. Fátima; Simal-Gandara, Jesus; Prieto, Miguel A.

The increasing demand for nutraceuticals in the circular economy era has driven the research toward studying bioactive compounds from renewable underexploited resources. In this regard, the exploration of brown algae has shown significant growth and maintains a great promise for the future. One possible explanation could be that brown algae are rich sources of nutritional compounds (polyunsaturated fatty acids, fiber, proteins, minerals, and vitamins) and unique metabolic compounds (phlorotannins, fucoxanthin, fucoidan) with promising biological activities that make them good candidates for nutraceutical applications with increased value-added. In this review, a deep description of bioactive compounds from brown algae is presented. In addition, recent advances in biological activities ascribed to these compounds through in vitro and in vivo assays are pointed out. Delivery strategies to overcome some drawbacks related to the direct application of algae-derived compounds (low solubility, thermal instability, bioavailability, unpleasant organoleptic properties) are also reviewed. Finally, current commercial and legal statuses of ingredients from brown algae are presented, considering future therapeutical and market perspectives as nutraceuticals.

2022Journal article

Restricted access

Nanostructured label–free electrochemical immunosensor for detection of a Parkinson's disease biomarker

Publication . Carneiro, Pedro; Loureiro, Joana A.; Delerue-Matos, Cristina; Morais, Simone; Pereira, Maria do Carmo

Aggregation of α-synuclein has been recognized as a critical event in the pathogenesis of Parkinson's disease whose prevalence is increasing with great socio-economic challenges for future generations. Here, we developed a sensitive and specific electrochemical immunosensor for the detection and quantification of this biomarker, based on the voltammetric study of a redox indicator signal, which decreases upon the analyte recognition by the antibody due to the electronic resistance increase. The proposed immunosensor is based on a screen-printed carbon electrode modified in a layer-by-layer approach, which through extensive characterization led to the successful nanostructuration of the transducer, through the drop-cast of 3.0 μL of a 0.1 mg mL−1 single-walled carbon nanotubes suspension followed by electrodeposition of gold nanoparticles in a 3 mM HAuCl4 solution under a −0.2 V potential for 150 s. Monoclonal antibodies were immobilized on the gold nanoparticles surface through chemical modification at an optimal concentration of 200 μg mL−1. Using the proposed immunosensor, α-synuclein was detected in the range of 0.01–10 ng mL−1 with a 4.1 and 12.6 pg mL−1 limits of detection and quantification, respectively. Recovery values of 96.7, 106.2 and 102.9% were attained for the tested concentrations spiked in fetal bovine serum while also presenting excellent specificity and stability throughout one month. The nanostructured immunosensor provided a great interface for electronic transduction and biological recognition events, which enabled fast, sensitive and specific detection of α-synuclein while being based on a simple and inexpensive technology requiring small sample volumes, crucial characteristics for application in point-of-care testing.

2023Journal article

Restricted access

Association of 3-Phenoxybenzoic Acid Exposure during Pregnancy with Maternal Outcomes and Newborn Anthropometric Measures: Results from the IoMum Cohort Study

Publication . Guimarães, Juliana; Bracchi, Isabella; Pinheiro, Cátia; Moreira, Nara Xavier; Coelho, Cláudia Matta; Pestana, Diogo; Prucha, Maria do Carmo; Martins, Cristina; Domingues, Valentina F.; Delerue-Matos, Cristina; Dias, Cláudia C.; Azevedo, Luís Filipe R.; Calhau, Conceição; Leite, João Costa; Ramalho, Carla; Keating, Elisa; Fernandes, Virgínia Cruz

The aims of this study were to characterize the exposure of pregnant women living in Portugal to 3-phenoxybenzoic acid (3-PBA) and to evaluate the association of this exposure with maternal outcomes and newborn anthropometric measures. We also aimed to compare exposure in summer with exposure in winter. Pregnant women attending ultrasound scans from April 2018 to April 2019 at a central hospital in Porto, Portugal, were invited to participate. Inclusion criteria were: gestational week between 10 and 13, confirmed fetal vitality, and a signature of informed consent. 3-PBA was measured in spot urine samples by gas chromatography with mass spectrometry (GC-MS). The median 3-PBA concentration was 0.263 (0.167; 0.458) μg/g creatinine (n = 145). 3-PBA excretion was negatively associated with maternal pre-pregnancy body mass index (BMI) (p = 0.049), and it was higher during the summer when compared to winter (p < 0.001). The frequency of fish or yogurt consumption was associated positively with 3-PBA excretion, particularly during the winter (p = 0.002 and p = 0.015, respectively), when environmental exposure is low. Moreover, 3-PBA was associated with levothyroxine use (p = 0.01), a proxy for hypothyroidism, which could be due to a putative 3-PBA—thyroid hormone antagonistic effect. 3-PBA levels were not associated with the anthropometric measures of the newborn. In conclusion, pregnant women living in Portugal are exposed to 3-PBA, particularly during summer, and this exposure may be associated with maternal clinical features.

2023Journal article

Open access