Browsing by Author "Nunes, Cláudia"
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- Chrysotila pseudoroscoffensis as a source of high-value polar lipids with antioxidant activity: A lipidomic approachPublication . Moreira, Ana S. P.; Gonçalves, Joana; Conde, Tiago A.; Couto, Daniela; Melo, Tânia; Maia, Inês Beatriz; Pereira, Hugo; Silva, Joana; Domingues, M. Rosário; Nunes, CláudiaMicroalgae are emerging as sustainable sources of a wide range of high-value compounds. However, the knowledge about microalgae polar lipids is still limited, despite their interest due to their chemical diversity and bioactivity. This study shows, for the first time, the polar lipidome of the haptophyte microalga Chrysotila pseudoroscoffensis unveiled by using hydrophilic interaction liquid chromatography-high resolution mass spectrometry (HILIC-HRMS and MS/MS) and gas chromatography-mass spectrometry (GC-MS). Freeze-dried C. pseudoroscoffensis biomass has a lipid content of 6.4 %, containing higher amounts of ash (45.5 %), proteins (11.6 %), and sugars (11.0 %). Uronic acids (53.8 mol%) are the sugars present in higher content, followed by glucose (13.7 mol%) and galactose (12.7 mol%). The polar lipid species identified by HILIC-MS/MS included betaine lipids, glycolipids, and phospholipids, some of them with recognised bioactive properties. Among the lipid classes found from C. pseudoroscoffensis, some are less reported in algae: betaine lipids diacylglycerylcarboxyhydroxymethylcholine (DGCC) and monoacylglycerylcarboxyhydroxymethylcholine (MGCC) (characteristic of haptophyte microalgae); acid glycolipid class glucuronosyldiacylglycerol (GlcADG) (mainly reported in plants with protective effects in phosphate-deprivation conditions); and phospholipid classes monomethylphosphatidylethanolamine (MMPE) and lysomonomethylphosphatidylethanolamine (MMLPE). As estimated by colorimetric assays, glycolipids and phospholipids accounted for 64 and 3 % of the total lipid extracts, respectively. Fatty acid profiling by GC-MS showed that total esterified fatty acids accounted for about 32 % of the total lipid extracts, of which 23 % were omega-3 polyunsaturated fatty acids (PUFA). Four lipid extract concentrations (12.5, 62.5, 125 and 250 mu g mL-1 in ethanol) were tested and displayed antioxidant capacity toward 2,2 & PRIME;-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals. A dose-dependent behaviour was observed with IC50 of 111.9 mu g mL(-1) for ABTS and IC35 of 234.8 mu g mL(-1) for DPPH assay. In conclusion, the lipid extracts of C. pseudoroscoffensis may be a source of high-value lipids for the development of novel microalgae-based products, namely nutraceuticals and cosmeceuticals.
- Nutritional potential and toxicological evaluation of tetraselmis sp. CTP4 microalgal biomass produced in industrial photobioreactorsPublication . Pereira, Hugo; Silva, Joana; Santos, Tamara; Gangadhar, Katkam N.; Raposo, Ana; Nunes, Cláudia; Coimbra, Manuel A.; Gouveia, Luísa; Barreira, Luísa; Varela, JoãoCommercial production of microalgal biomass for food and feed is a recent worldwide trend. Although it is common to publish nutritional data for microalgae grown at the lab-scale, data about industrial strains cultivated in an industrial setting are scarce in the literature. Thus, here we present the nutritional composition and a microbiological and toxicological evaluation of Tetraselmis sp. CTP4 biomass, cultivated in 100-m3 photobioreactors at an industrial production facility (AlgaFarm). This microalga contained high amounts of protein (31.2 g/100 g), dietary fibres (24.6 g/100 g), digestible carbohydrates (18.1 g/100 g) and ashes (15.2 g/100 g), but low lipid content (7.04 g/100 g). The biomass displayed a balanced amount of essential amino acids, n-3 polyunsaturated fatty acids, and starch-like polysaccharides. Significant levels of chlorophyll (3.5 g/100 g), carotenoids (0.61 g/100 g), and vitamins (e.g., 79.2 mg ascorbic acid /100 g) were also found in the biomass. Conversely, pathogenic bacteria, heavy metals, cyanotoxins, mycotoxins, polycyclic aromatic hydrocarbons, and pesticides were absent. The biomass showed moderate antioxidant activity in several in vitro assays. Taken together, as the biomass produced has a balanced biochemical composition of macronutrients and (pro-)vitamins, lacking any toxic contaminants, these results suggest that this strain can be used for nutritional applications.
- Potential of Coccolithophore microalgae as fillers in starch-based films for active and sustainable food packagingPublication . Moreira, Ana S. P.; Gonçalves, Joana; Sousa, Francisco; Maia, Inês Beatriz; Pereira, Hugo; Silva, Joana; Coimbra, Manuel A.; Ferreira, Paula; Nunes, CláudiaCoccolithophore microalgae, such as Emiliania huxleyi (EHUX) and Chrysotila pseudoroscoffensis (CP), are composed of calcium carbonate (CaCO3) and contain bioactive compounds that can be explored to produce sustainable food packaging. In this study, for the first time, these microalgae were incorporated as fillers in starch-based films, envisioning the development of biodegradable and bioactive materials for food packaging applications. The films were obtained by solvent casting using different proportions of the filler (2.5, 5, 10, and 20%, w/w). For comparison, commercial CaCO3, used as filler in the plastic industry, was also tested. The incorporation of CaCO3 and microalgae (EHUX or CP) made the films significantly less rigid, decreasing Young’s modulus up to 4.7-fold. Moreover, the incorporation of microalgae hydrophobic compounds as lipids turned the surface hydrophobic (water contact angles > 90°). Contrary to what was observed with commercial CaCO3, the films prepared with microalgae exhibited antioxidant activity, increasing from 0.9% (control) up to 60.4% (EHUX 20%) of ABTS radical inhibition. Overall, the introduction of microalgae biomass improved hydrophobicity and antioxidant capacity of starch-based films. These findings should be considered for further research using coccolithophores to produce active and sustainable food packaging material.
- Simple and effective chitosan based films for the removal of Hg from waters: Equilibrium, kinetic and ionic competitionPublication . Rocha, Luciana S.; Almeida, Ângela; Nunes, Cláudia; Henriques, Bruno; Coimbra, Manuel A.; Lopes, Cláudia B.; Silva, Carlos M.; Duarte, Armando C.; Pereira, EduardaThe efficiency of chitosan cross-linked with genipin (Chg) and cross-linked with genipin and grafted with caffeic acid (Ch(g+car)) to remove Hg(II) from waters was investigated. An optimal dose of 50 mg L-1 for both chitosan films was selected based on the equilibrium removal percentage and on the contact time required to attain the equilibrium. The sorption extent was dependent on the initial Hg(II) concentration (C-Hg,C-0), with removal efficiencies varying between 79% and 82% for C-Hg,C-0 = 0.05 mg L-1 and between 89% and 94% for C-Hg,C-0 = 0.50 mg L-1. Under ion competition, the Ch(g) and Ch(g+caf) films showed to be effective and selective for mercury in multimetallic solutions containing also cadmium and lead. In the case of natural river and seawaters, the mercury speciation played an important role in the overall sorption process, reducing the percentage removal of Hg. In terms of modeling, the kinetic data were well described by pseudo-first and pseudo-second order models, depending on the experimental conditions. The diffusion models suggested that the entire sorption process of Hg(II) by both Chg and Chg+caf films was essentially controlled by pore diffusion. The equilibrium data were well described by the Sips isotherm, and the estimated capacity was 2.2 and 4.0 mg g(-1) for Chg and Ch(g+caf) films, respectively. In the whole, the results showed that the sorption efficiency was improved by grafting caffeic acid to the polymeric chains of chitosan cross-linked with genipin. (C) 2016 Elsevier B.V. All rights reserved.
- The polar lipidome of cultured Emiliania huxleyi: a source of bioactive lipids with relevance for biotechnological applicationsPublication . Aveiro, Susana S.; Melo, Tânia; Figueiredo, Ana; Domingues, Pedro; Pereira, Hugo; Maia, Inês Beatriz; Silva, Joana; Domingues, M. Rosário; Nunes, Cláudia; Moreira, Ana S. P.Polar lipids from microalgae have aroused greater interest as a natural source of omega-3 (n-3) polyunsaturated fatty acids (PUFA), an alternative to fish, but also as bioactive compounds with multiple applications. The present study aims to characterize the polar lipid profile of cultured microalga Emiliania huxleyi using hydrophilic interaction liquid chromatography coupled with high-resolution mass spectrometry (HILIC-MS) and fatty acids (FA) analysis by gas chromatography (GC-MS). The lipidome of E. huxleyi revealed the presence of distinct n-3 PUFA (40% of total FA), namely docosahexaenoic acid (22:6n-3) and stearidonic acid (18:4n-3), which give this microalga an increased commercial value as a source of n-3 PUFA present in the form of polar lipids. A total of 134 species of polar lipids were identified and some of these species, particularly glycolipids, have already been reported for their bioactive properties. Among betaine lipids, the diacylglyceryl carboxyhydroxymethylcholine (DGCC) class is the least reported in microalgae. For the first time, monomethylphosphatidylethanolamine (MMPE) has been found in the lipidome of E. huxleyi. Overall, this study highlights the potential of E. huxleyi as a sustainable source of high-value polar lipids that can be exploited for different applications, namely human and animal nutrition, cosmetics, and pharmaceuticals.