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

Carbon dots de síntese única para deteção de espécies reativas de oxigénio

Publication . Almeida, Lícia; Sousa, Cátia A.; Duarte, Abel J.

(Introdução) As espécies reativas de oxigénio (reactive oxygen species – ROS), são um conjunto de radicais livres que derivam do oxigénio e provêm da cadeia respiratória. São de importância vital nos organismos vivos em quantidade muito reduzidas, funcionando como neurotransmissores ou vasodilatadores, no entanto, quando em grandes quantidades provocam o stresse oxidativo causador de inúmeras patologias. A deteção ROS é de grande importância em diversos processos biológicos, diagnóstico de doenças e triagem de drogas quimioterápicas, para isso é importante construir unidades de carbon dots (Cdots) que sejam sensores químicos de ROS por mecanismo de extinção de fluorescência. Existem algumas estratégias de construção dos CDots, as mais vantajosas são as sínteses únicas em micro-ondas.

2024Conference object

Open 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

Synthesis and Antibacterial Activity of Ionic Liquids and Organic Salts Based on Penicillin G and Amoxicillin hydrolysate Derivatives against Resistant Bacteria

Publication . Ferraz, Ricardo; Silva, Dário; Dias, Ana Rita; Dias, Vitorino; Santos, Miguel M.; Pinheiro, Luís; Prudêncio, Cristina; Noronha, João Paulo; Petrovski, Željko; Branco, Luís C.

The preparation and characterization of ionic liquids and organic salts (OSILs) that contain anionic penicillin G [secoPen] and amoxicillin [seco-Amx] hydrolysate derivatives and their in vitro antibacterial activity against sensitive and resistant Escherichiacoli and Staphylococcusaureus strains is reported. Eleven hydrolyzed β-lactam-OSILs were obtained after precipitation in moderate-to-high yields via the neutralization of the basic ammonia buffer of antibiotics with different cation hydroxide salts. The obtained minimum inhibitory concentration (MIC) data of the prepared compounds showed a relative decrease of the inhibitory concentrations (RDIC) in the order of 100 in the case of [C2OHMIM][seco-Pen] against sensitive S. aureus ATCC25923 and, most strikingly, higher than 1000 with [C16Pyr][seco-Amx] against methicillin-resistant Staphylococcus aureus (MRSA) ATCC 43300. These outstanding in vitro results showcase that a straightforward transformation of standard antibiotics into hydrolyzed organic salts can dramatically change the pharmaceutical activity of a drug, including giving rise to potent formulations of antibiotics against deadly bacteria strains.

2020Journal article

Open access