Associated Laboratory for Green Chemistry - Clean Technologies and Processes

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Publications

Roots and rhizomes of wild Asparagus: nutritional composition, bioactivity and nanoencapsulation of the most potent extract

Publication . Adouni, Khaoula; Júlio, Ana; Santos-Buelga, Celestino; González-Paramás, Ana M.; Filipe, Patrícia; Rijo, Patricia; Costa Lima, Sofia A.; Reis, Salette; Fernandes, Ângela; Ferreira, Isabel C.F.R.; Fernández-Ruiz, Virginia; Morales, Patricia; Flamini, Guido; Achour, Lotfi; Fonte, Pedro

The nutritional composition and bioactive properties of roots and rhizomes of Asparagus stipularis were evalu- ated. Antioxidant activity of extracts obtained by infusion was evaluated using free radicals scavenging and reducing power methods. Porcine liver primary cell was used to check the hepatotoxicity of infusions. Results revealed that Asparagus samples are likely a source of nutrients, such as dietary fibre and essential fatty acids. HPLC-DAD-ESI/MS characterization of infusions allowed the identification and quantitation of 7 phenolic compounds, all hydroxycinnamoyl derivatives, with caffeic acid as the most abundant. Roots infusion contained the highest amounts of these compounds. It also exhibited the highest antioxidant activity in all assays, with EC50 values of 0.44 ± 0.01, 0.98 ± 0.03 and 0.64 ± 0.01 mg/mL for DPPH, ABTS and FRAP assays, respectively, with no toxicity towards PLP2 primary cell cultures (GI50 > 400 μg/mL). PLGA nanoparticles loaded with root extract were prepared using solvent-evaporation double emulsion method. Nanoparticles size was about 260 nm and a polydispersity index around 0.1, with a zeta potential of about -36 mV, as well as a good encapsulation efficiency of approximately 83%. Their morphology was analysed by SEM and spherical polymeric nanoparticles with a smooth surface were observed. FTIR and DSC were also performed, which allowed corroborating the efficacy of the encapsulation and to confirm the production of a stable and robust system to load Asparagus extracts. The developed nanoparticles are expected to be used as delivery systems for bioactive compounds of A. stipularis and they could be used as an innovative dietary supplement.

2022Journal article

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A silicododecamolybdate/pyridinium-tetrazole hybrid molecular salt as a catalyst for the epoxidation of bio-derived olefins

Publication . Nunes, Martinique S.; Neves, Patricia; Gomes, Ana C.; Cunha-Silva, Luis; Lopes, Andre D.; Valente, Anabela A.; Pillinger, Martyn; Goncalves, Isabel S.

The hybrid polyoxometalate (POM) salt (Hptz)(4)[SiMo12O40].nH(2)O (1) (ptz = 5-(2-pyridyl)tetrazole) has been prepared, characterized by X-ray crystallography, and examined as a catalyst for the epoxidation of cis-cyclooctene (Cy) and bio-derived olefins, namely dl-limonene (Lim; a naturally occurring monoterpene found in the rinds of citrus fruits), methyl oleate and methyl linoleate (fatty acid methyl esters (FAMEs) obtained by transesterification of vegetable oils). The crystal structure of 1 consists of alpha-Keggin-type heteropolyanions, [SiMo12O40](4-), surrounded by space-filling and charge-balancing 2-(tetrazol-5-yl)pyridinium (Hptz(+)) cations, as well as by a large number of water molecules of crystallization (n = 9). The water molecules mediate an extensive three-dimensional (3D) hydrogen-bonding network involving the inorganic anions and organic cations. For the epoxidation of the model substrate Cy in a nonaqueous system (tert-butylhydroperoxide as oxidant), the catalytic performance of 1 (100% epoxide yield at 24 h, 70 degrees C) was superior to that of the tetrabutylammonium salt (Bu4N)(4) [SiMo12O40] (2) (63% epoxide yield at 24 h), illustrating the role of the counterion Hptz(+) in enhancing catalytic activity. The hybrid salt 1 was effective for the epoxidation of Lim (69%/85% conversion at 6 h/24 h) and the FAMEs (87-88%/100% conversion at 6 h/24 h), leading to useful bio-based products (epoxides, diepoxides and diol products).

2021-02Journal article

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Evaluation of the antitumour and antiproliferative effect of Xanthohumol-Loaded PLGA nanoparticles on melanoma

Publication . Fonseca, Magda; Macedo, Ana S.; Lima, Sofia A. Costa; Reis, Salette; Soares, Raquel; Fonte, Pedro

Cutaneous melanoma is the deadliest type of skin cancer and current treatment is still inadequate, with low patient survival rates. The polyphenol xanthohumol has been shown to inhibit tumourigenesis and metastasization, however its physicochemical properties restrict its application. In this work, we developed PLGA nanoparticles encapsulating xanthohumol and tested its antiproliferative, antitumour, and migration effect on B16F10, malignant cutaneous melanoma, and RAW 264.7, macrophagic, mouse cell lines. PLGA nanoparticles had a size of 312 ± 41 nm and a PdI of 0.259, while achieving a xanthohumol loading of about 90%. The viability study showed similar cytoxicity between the xanthohumol and xanthohumol-loaded PLGA nanoparticles at 48 h with the IC50 established at 10 µM. Similar antimigration effects were observed for free and the encapsulated xanthohumol. It was also observed that the M1 antitumor phenotype was stimulated on macrophages. The ultimate anti-melanoma effect emerges from an association between the viability, migration and macrophagic phenotype modulation. These results display the remarkable antitumour effect of the xanthohumol-loaded PLGA nanoparticles and are the first advance towards the application of a nanoformulation to deliver xanthohumol to reduce adverse effects by currently employed chemotherapeutics.

2021-10-26Journal article

Open Access

Effects of outdoor and indoor cultivation on the polar lipid composition and antioxidant activity of Nannochloropsis oceanica and Nannochloropsis limnetica: A lipidomics perspective

Publication . Couto, Daniela; Conde, Tiago A.; Melo, Tânia; Neves, Bruna; Costa, Margarida; Cunha, Pedro; Guerra, Inês; Correia, Nádia; Silva, Joana T.; Pereira, Hugo; Varela, João; Silva, Joana; Domingues, Rosário; Domingues, Pedro

Nannochloropsis is a genus of eicosapentaenoic acid-rich microalgae with high levels of value-added polar lipids. However, the polar lipid composition of microalgal biomass is highly dependent on culture conditions (e.g., light or temperature), which are significantly different under indoor and outdoor culture conditions. In this study, we sought to investigate the plasticity of the polar lipid profile of a marine (N. oceanica) and a freshwater (N. limnetica) species of Nannochloropsis grown in indoor and outdoor photobioreactors. To this end, the polar lipidome and fatty acid profiles were characterized by liquid chromatography-mass spectrometry (LC-MS), and gas chromatography-mass spectrometry (GC-MS), respectively. In addition, the antioxidant activity of their lipid extracts was assessed. The highest lipid contents were obtained for the two species grown indoors. LC-MS analysis identified 239 different polar lipid species, of which 220 were shared by all experimental groups. Candidate lipid biomarkers from both culture systems were proposed, including MGDG(34:2), MGDG(34:1) and PG(36:6). For both species, indoor conditions lead to lipid extracts rich in glycolipids and higher in oleic acid content. In contrast, outdoor conditions lead to higher proportions of phospholipids and betaine lipids and a higher relative content of eicosapentaenoic acid (EPA). The polar lipid profile of the two Nannochloropsis species differed primarily in the relative amounts of certain betaine lipids, mainly DGTS (which was increased in N. oceanica) and lysolipids (LPC, and LPE) (increased in N. limnetica), although the majority of lipids were observed in both species. The lipid extracts showed antioxidant activity (IC15) ranging from 30.4 +/- 1.8 to 45.7 +/- 1.6 mu mol Trolox g-1 of lipid extract. Overall, this study provides insight into the lipid metabolic adaptation of two Nannochloropsis species, providing the know-how to obtain a healthy polar lipid-rich biomass useful for novel applications in pharmaceutical, nutraceutical, or novel foods.

2022-05Journal article

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Light modulates the lipidome of the photosynthetic sea slug Elysia timida

Publication . Rey, Felisa; Cartaxana, Paulo; Aveiro, Susana; Greenacre, Michael; Melo, Tânia; Domingues, Pedro; Domingues, M. Rosário; Cruz, Sónia

Long-term kleptoplasty, the capability to retain functional stolen chloroplasts (kleptoplasts) for several weeks to months, has been shown in a handful of Sacoglossa sea slugs. One of these sea slugs is Elysia timida, endemic to the Mediterranean, which retains functional chloroplasts of the macroalga Acetabularia acetabulum. To understand how light modulates the lipidome of E. timida, sea slug specimens were subjected to two different 4-week light treatments: regular light and quasi-dark conditions. Lipidomic analyses were performed by HILIC-HR-ESIMS and MS/MS. Quasi-dark conditions caused a reduction in the amount of essential lipids for photosynthetic membranes, such as glycolipids, indicating high level of kleptoplast degradation under sub-optimal light conditions. However, maximum photosynthetic capacities (Fv/Fm) were identical in both light treatments (≈0.75), showing similar kleptoplast functionality and suggesting that older kleptoplasts were targeted for degradation. Although more stable, the phospholipidome showed differences between light treatments: the amount of certain lipid species of phosphatidylethanolamine (PE), phosphatidylinositol (PI), and phosphatidylglycerol (PG) decreased under quasi-dark conditions, while other lipid species of phosphatidylcholine (PC), PE and lyso-PE (LPE) increased. Quasi-dark conditions promoted a decrease in the relative abundance of polyunsaturated fatty acids. These results suggest a light-driven remodelling of the lipidome according to the functions of the different lipids and highlight the plasticity of polar lipids in the photosynthetic sea slug E. timida.

2023Journal article

Open Access