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  • Antileishmanial activity of meroditerpenoids from the macroalgae Cystoseira baccata
    Publication . Sousa, Carolina Bruno de; Gangadhar, Katkam N.; Morais, Thiago R.; Conserva, Geanne A. A.; Vizetto-Duarte, C; Pereira, H.; Laurenti, Marcia D.; Campino, Lenea; Levy, Debora; Uemi, Miriam; Barreira, Luísa; Custódio, L.; Passero, Luiz Felipe D.; Lago, Joao Henrique G.; Varela, João
    The development of novel drugs for the treatment of leishmaniases continues to be crucial to overcome the severe impacts of these diseases on human and animal health. Several bioactivities have been described in extracts from macroalgae belonging to the Cystoseira genus. However, none of the studies has reported the chemical compounds responsible for the antileishmanial activity observed upon incubation of the parasite with the aforementioned extracts. Thus, this work aimed to isolate and characterize the molecules present in a hexane extract of Cystoseira baccata that was found to be bioactive against Leishmania infantum in a previous screening effort. A bioactivity-guided fractionation of the C. baccata extract was carried out and the inhibitory potential of the isolated compounds was evaluated via the MIT assay against promastigotes and murine macrophages as well as direct counting against intracellular amastigotes. Moreover, the promastigote ultrastructure, DNA fragmentation and changes in the mitochondrial potential were assessed to unravel their mechanism of action. In this process, two antileishmanial meroditerpenoids, (3R)- and (3S)-tetraprenyltoluquinol (1a/1b) and (3R)- and (3S)-tetraprenyltoluquinone (2a/2b), were isolated. Compounds 1 and 2 inhibited the growth of the L. infantum promastigotes (IC50 = 44.9 +/- 4.3 and 94.4 +/- 10.1 mu M, respectively), inducing cytoplasmic vacuolization and the presence of coiled multilamellar structures in mitochondria as well as an intense disruption of the mitochondrial membrane potential. Compound 1 decreased the intracellular infection index (IC50 = 25.0 +/- 4.1 mu M), while compound 2 eliminated 50% of the intracellular amastigotes at a concentration > 88.0 mu M. This work identified compound 2 as a novel metabolite and compound 1 as a biochemical isolated from Cystoseira algae displaying antileishmanial activity. Compound 1 can thus be an interesting scaffold for the development of novel chemotherapeutic molecules for canine and human visceral leishmaniases studies. This work reinforces the evidence of the marine environment as source of novel molecules. (C) 2017 Elsevier Inc. All rights reserved.
  • Isolation of a euryhaline microalgal strain, Tetraselmis sp CTP4, as a robust feedstock for biodiesel production
    Publication . Pereira, Hugo; Gangadhar, Katkam N.; Schulze, Peter S.C.; Santos, Tamara; de Sousa, Carolina Bruno; Schueler, Lisa; Custódio, Luísa; Malcata, F. Xavier; Gouveia, Luísa; Varela, J.; Barreira, Luísa
    Bioprospecting for novel microalgal strains is key to improving the feasibility of microalgae-derived biodiesel production. Tetraselmis sp. CTP4 (Chlorophyta, Chlorodendrophyceae) was isolated using fluorescence activated cell sorting (FACS) in order to screen novel lipid-rich microalgae. CTP4 is a robust, euryhaline strain able to grow in seawater growth medium as well as in non-sterile urban wastewater. Because of its large cell size (9-22 mu m), CTP4 settles down after a six-hour sedimentation step. This leads to a medium removal efficiency of 80%, allowing a significant decrease of biomass dewatering costs. Using a two-stage system, a 3-fold increase in lipid content (up to 33% of DW) and a 2-fold enhancement in lipid productivity (up to 52.1 mg L-1 d(-1)) were observed upon exposure to nutrient depletion for 7 days. The biodiesel synthesized from the lipids of CTP4 contained high levels of oleic acid (25.67% of total fatty acids content) and minor amounts of polyunsaturated fatty acids with >= 4 double bonds (< 1%). As a result, this biofuel complies with most of the European (EN14214) and American (ASTM D6751) specifications, which commonly used microalgal feedstocks are usually unable to meet. In conclusion, Tetraselmis sp. CTP4 displays promising features as feedstock with lower downstream processing costs for biomass dewatering and biodiesel refining.
  • Assessment and comparison of the properties of biodiesel synthesized from three different types of wet microalgal biomass
    Publication . Gangadhar, Katkam N.; Pereira, Hugo; Diogo, Herminio P.; Borges dos Santos, R. M.; Devi, B. L. A. Prabhavathi; Prasad, R. B. N.; Custódio, Luísa; Xavier Malcata, F.; Varela, João; Barreira, Luísa
    In recent years, microalgae-based carbon-neutral biofuels (i.e., biodiesel) have gained considerable interest due to high growth rate and higher lipid productivity of microalgae during the whole year, delivering continuous biomass production as compared to vegetable-based feedstocks. Therefore, biodiesel was synthesized from three different microalgal species, namely Tetraselmis sp. (Chlorophyta) and Nannochloropsis oculata and Phaeodactylum tricornutum (Heterokontophyta), and the fuel properties of the biodiesel were analytically determined, unlike most studies which rely on estimates based on the lipid profile of the microalgae. These include density, kinematic viscosity, total and free glycerol, and high heating value (HHV), while cetane number (CN) and cold filter plugging point (CFPP) were estimated based on the fatty acid methyl ester profile of the biodiesel samples instead of the lipid profile of the microalgae. Most biodiesel properties abide by the ASTM D6751 and the EN 14214 specifications, although none of the biodiesel samples met the minimum CN or the maximum content of polyunsaturated fatty acids with a parts per thousand yen4 double bonds as required by the EN 14214 reference value. On the other hand, bomb calorimetric experiments revealed that the heat of combustion of all samples was on the upper limit expected for biodiesel fuels, actually being close to that of petrodiesel. Post-production processing may overcome the aforementioned limitations, enabling the production of biodiesel with high HHV obtained from lipids present in these microalgae.
  • A comparative study of the in vitro enzyme inhibitory and antioxidant activities of Butea monosperma (Lam.) Taub. and Sesbania grandiflora (L.) Poiret from Pakistan: New sources of natural products for public health problems
    Publication . Baessa, M.; Rodrigues, Maria João; Pereira, Catarina; Santos, T.; Neng, N. da Rosa; Nogueira, J. M. F.; Barreira, Luísa; Varela, J.; Ahmed, H.; Asif, S.; Boukhari, S. A.; Kayani, W. K.; Ahmad, Khawaja Shafique; Zengin, G.; Mollica, A.; Custódio, Luísa
    Infusions, decoctions and tinctures were prepared from flowers of Butea monosperma (Lam.) Taub. and Sesbania grandiflora (L.) Poiret and evaluated for in vitro inhibition of enzymes implicated on the onset of neurological diseases (acetylcholinesterase: AChE and butyrylcholinesterase: BuChE), diabetes (alpha-glucosidase and alpha-amylase), obesity (lipase) and skin hyperpigmentation (tyrosinase). Extracts were also appraised for radical scavenging activity (RSA) on 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radicals, and for metal chelating activity on copper and iron ions. Samples were evaluated for their total contents in different phenolics groups by spectrophotometric methods, for phenolic profile by high performance liquid chromatography e diode array detection (HPLC-DAD) and for mineral contents by microwave plasma-atomic emission spectrometry (MP-AE). Regarding B. monosperma, the tincture allowed for a moderate inhibition of AChE, the decoction was able to inhibit alpha-glucosidase and no activity was observed towards BuChE, alpha-amylase or lipase. All extracts had a low or moderate inhibition towards tyrosinase, and significant RSA and metal chelating potential. As for S. grandiflora, only the decoction inhibited AChE, none of the extracts was able to inhibit BuChE, all samples inhibited alpha-glucosidase and infusions and decoctions had similar inhibitory properties towards alpha-amylase. None of the extracts was active against lipase, but all were able to inhibit tyrosinase. Extracts had also significant RSA, moderate copper chelation and decoctions had the capacity to chelate iron. The most abundant macroelements in both species were potassium and calcium, while iron was the prevalent microelement, especially in B. monosperma. Both species had significant levels of phenolic compounds, and the main components in decoctions and infusions of B. monosperma were syringic and salicylic acids, while the major compound identified in tinctures was the flavonoid luteolin-7-O-glucoside. In S. grandiflora the most abundant were chlorogenic and neochlorogenic acids and catechin hydrate. Molecular docking studies on the most abundant molecules in S. grandiflora, (+)-catechin, chlorogenic acid and neochlorogenic acid, indicate that these compounds are able to dock to alpha-glucosidase in a similar manner than acarbose. Our results suggest that flowers of both species are a promising source of high value-added compounds with enzyme inhibitory and antioxidant properties. (c) 2018 SAAB. Published by Elsevier B.V. All rights reserved.
  • First report of the nutritional profile and antioxidant potential of Holothuria arguinensis, a new resource for aquaculture in Europe
    Publication . Roggatz, Christina C.; Gonzalez-Wanguemert, Mercedes; Pereira, Hugo; Rodrigues, Maria Joao; F. G. M. Silva, Manuela; Barreira, Luísa; Varela, João; Custódio, Luísa
    This work reports for the first time the nutritional profile and antioxidant potential of the edible sea cucumber Holothuria arguinensis from the North-eastern Atlantic. H. arguinensis has high levels of protein, with the amino acids profile dominated by alanine, glycine and proline and low lysine/arginine ratios. Its carbohydrate and energetic contents are also low as well as the total lipid levels, although its lipid profile is rich in polyunsaturated fatty acids (PUFA), especially arachidonic, eicosapentaenoic and docosahexaenoic acids. In addition, H. arguinensis has high levels of calcium. The water and ethanol extracts show ability to scavenge free radicals and to chelate copper and iron ions. Our results indicate that H. arguinensis has a balanced nutritional quality suitable for human consumption. In addition, it contains compounds with antioxidant potential; thus its intake can contribute for a healthy and well-balanced diet.
  • Proximate biochemical composition and mineral content of edible species from the genus Cystoseira in Portugal
    Publication . Vizetto-Duarte, C; Custódio, Luísa; Barreira, Luísa; da Silva, Manuela Moreira; Rauter, Amelia P.; Albericio, Fernando; Varela, J.
    Macroalgae are valuable resources for human consumption in many countries. This work reports for the first time a comparative evaluation of the nutritional properties of five edible macroalgae from the genus Cystoseira, namely C. humilis, C. tamariscifolia, C. nodicaulis, C. compressa and C. baccata. For this purpose, their proximate composition was determined in terms of moisture, ash, and total contents of protein, lipids, carbohydrates and mineral profile. Cystoseira tamariscifolia and C. baccata were the species that in general had the higher ash, protein and lipid contents, while the highest levels of moisture and total carbohydrates were detected in C. nodicaulis and C. compressa. Cystoseira species had also high amounts of minerals, especially of potassium, calcium and iron, and a favorable Na/K ratio. The present study shows that Cystoseira has a balanced nutritional composition, suitable for human consumption, and that its intake can contribute to a healthy and well-balanced diet.
  • Coupling sea lavender (Limonium algarvense Erben) and green tea (Camellia sinensis (L.) Kuntze) to produce an innovative herbal beverage with enhanced enzymatic inhibitory properties
    Publication . Rodrigues, Maria João; Oliveira, M.; Neves, V.; Ovelheiro, Andreia; Pereira, C. A.; Neng, N. R.; Nogueira, J. M. F.; Varela, J.; Barreira, Luísa; Custódio, Luísa
    Herbal beverages containing mixtures of L. algarvense (LA) flowers and C. sinensis (CS) were prepared and their inhibitory properties towards enzymes related with Alzheimer's (acetyl-and butyrylcholinesterase) and Type-2 diabetes mellitus (alpha-amylase and alpha-glucosidase) were evaluated for the first time. Samples were also appraised for antioxidant capacity and phenolic contents by high-performance liquid chromatography with diode-array detection (HPLC-DAD). Both synergistic and antagonistic interactions were observed: LA samples (infusion: IC50 = 0.22 mg/mL; decoction: 0.39 mg/mL) had higher acetylcholinesterase inhibition than CS and mixtures resulted in stronger enzymatic inhibition. CS had the highest rat alpha-glucosidase inhibition (infusion: IC50 = 3.91 mg/mL; decoction: IC50 = 2.50 mg/mL), which decreased when combined with LA. LA and CS samples had strong antioxidant activity, whereas LA and CS mixtures exhibited higher OH center dot radical-scavenging (0.56 <= SE <= 1.07) and anti-lipid peroxidation capacity (0.39 <= SE <= 0.81). CS had higher phenolic contents (infusion: 209 mg/g DW; decoction: 169 mg/g DW) and its combination with LA increased the phenolic diversity of the mixtures. Our results indicate that LA and CS infusions and decoctions and their combinations have relevant in vitro neuroprotective, antidiabetic and antioxidant properties and could be further explored as potential innovative functional beverages able to reduce the progression of neurodegenerative diseases and diabetic complications, and to prevent oxidative stress and lipid oxidation related diseases. (c) 2017 SAAB. Published by Elsevier B.V. All rights reserved.
  • A comparative evaluation of biological activities and bioactive compounds of the seagrasses Zostera marina and Zostera noltei from southern Portugal
    Publication . Custódio, Luísa; Laukaityte, Simona; Engelen, Aschwin; Rodrigues, Maria Joao; Pereira, Hugo; Vizetto-Duarte, C; Barreira, Luísa; Rodriguez, Hortensia; Albericio, Fernando; Varela, João
    This work assessed the antioxidant potential, acetylcholinesterase (AChE) inhibition and the in vitro cytotoxic activity of extracts of the seagrasses Zostera marina and Zostera noltei collected from southern Portugal. The total phenolic contents (TPCs), the rosmarinic acid (RA) concentration (HPLC/DAD) and the fatty acid (FA) profile (GC/MS) are also described. Z. marina had the highest TPC, radical scavenging activity against DPPH radicals and copper chelating activity. Z. noltei had metal chelation capacity to copper and iron ions. None of the species was able to inhibit AChE. Both seagrasses had high levels of polyunsaturated FAs. Z. marina significantly and selectively reduced the viability of tumorous neuronal cells. Z. noltei was highly toxic for the three cell lines tested and was selective against hepatocarcinoma cells at the concentration of 100g/mL. RA was the main compound identified in Z. marina, but not in Z. noltei.
  • Biological activities and chemical composition of methanolic extracts of selected Autochthonous microalgae strains from the Red Sea
    Publication . Pereira, Hugo; Custodio, Luisa; Rodrigues, Maria Joao; Bruno De Sousa, Carolina; Oliveira, Marta; Barreira, Luísa; Neng, Nuno da Rosa; Florencio Nogueira, Jose Manuel; Alrokayan, Salman A.; Mouffouk, Fouzi; Abu-Salah, Khalid M.; Ben-Hamadou, Radhouan; Varela, João
    Four lipid-rich microalgal species from the Red Sea belonging to three different genera (Nannochloris, Picochlorum and Desmochloris), previously isolated as novel biodiesel feedstocks, were bioprospected for high-value, bioactive molecules. Methanol extracts were thus prepared from freeze-dried biomass and screened for different biological activities. Nannochloris sp. SBL1 and Desmochloris sp. SBL3 had the highest radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl, and the best copper and iron chelating activities. All species had potent butyrylcholinesterase inhibitory activity (>50%) and mildly inhibited tyrosinase. Picochlorum sp. SBL2 and Nannochloris sp. SBL4 extracts significantly reduced the viability of tumoral (HepG2 and HeLa) cells with lower toxicity against the non-tumoral murine stromal (S17) cells. Nannochloris sp. SBL1 significantly reduced the viability of Leishmania infantum down to 62% (250 mu g/mL). Picochlorum sp. SBL2 had the highest total phenolic content, the major phenolic compounds identified being salicylic, coumaric and gallic acids. Neoxanthin, violaxanthin, zeaxanthin, lutein and -carotene were identified in the extracts of all strains, while canthaxanthin was only identified in Picochlorum sp. SBL2. Taken together, these results strongly suggest that the microalgae included in this work could be used as sources of added-value products that could be used to upgrade the final biomass value.
  • Searching for new sources of innovative products for the food industry within halophyte aromatic plants: In vitro antioxidant activity and phenolic and mineral contents of infusions and decoctions of Crithmum maritimum L.
    Publication . Pereira, Catarina Guerreiro; Barreira, Luísa; Neng, Nuno da Rosa; Florencio Nogueira, Jose Manuel; Marques, Catia; Santos, Tamara; Varela, J.; Custódio, Luísa
    Aromatic halophyte plants are an outstanding source of bioactive compounds and natural products with potential use in the food industry. This work reports the in vitro antioxidant activity, toxicity, poly phenolic profile and mineral contents of infusions and decoctions from stems, leaves and flowers of Crithmum maritimum L, an aromatic and edible maritime halophyte (sea fennel). Aspalathus linearis (Burm.f.) Dahlg. (rooibos) herbal tea was used as a reference. Sea fennel's tisanes, particularly from leaves, were rich in phenolic compounds and five of them (p-hydroxybenzoic and ferulic acids, epicatechin, pyrocatechol and 4-hydroxybenzaldehyde) were here described in C maritimum for the first time. Chlorogenic acid was the dominant phenolic determined. Na was the most abundant mineral in all tisanes followed by Ca and Mg in leaves' tisanes and K in flowers. Sea fennel's samples had a similar antioxidant activity than those from A. linearis, and had no significant toxicity towards four different mammalian cell lines. Altogether, our results suggest that sea fennel can be a source of products and/or molecules for the food industry with antioxidant properties and minerals in the form, for example, of innovative health-promoting herbal beverages.