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Mycorrhizal induction of phenolic compounds and antioxidant properties of fungi and seedlings during the early steps of symbiosis.

Publication . Reis, Filipa S.; Ferreira, Isabel C.F.R.; Barros, Lillian; Santos-Buelga, Celestino; Martins, Anabela

Ectomycorrhizal (ECM) symbiosis plays a major role in nutrient cycling and the functioning of forest ecosystems. Trees with well developed ectomycorrhizas are more resistant to environmental stresses such as drought and to biotic stresses such as root pathogens. The establishment of ECM symbiosis is triggered by signals produced by both partners. These signals lead to morphological changes and a complex development of specific structures in both the plant root and the fungus. The development of the ECM fungi, Paxillus involutus and Pisolithus arhizus, in presence and absence of the symbiont – Pinus pinaster- was evaluated, as well as their antioxidant properties and phenolic compounds composition in response to the symbiotic association. ECM fungi grew less in the presence of Pinus pinaster, with Pisolithus arhizus being less affected in growth and thus being more adapted to this association. Protocatechuic acid was found only in Paxillus involutus, while Pinus pinaster roots, both in association and isolated, proved to have other phenolic acids, such as p-hydroxybenzoic and p-coumaric acids. The symbiosis between Paxillus involutus and Pinus pinaster had no major effects on the symbionts, while the association between Pisolithus arhizus and Pinus pinaster seems to generally decrease the antioxidant effects of both symbionts, despite the increase in p-coumaric and cinnamic acids in the ECM fungi.

2011Journal article

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Comparing the composition and bioactivity of Crataegus monogyna flowers and fruits used in folk medicine

Publication . Barros, Lillian; Carvalho, Ana Maria; Ferreira, Isabel C.F.R.

Introduction- Studying local plant foods is of particular interest as they often contain high amounts of bioactive compounds. Furthermore, their nutritional and medicinal impact must be documented and supported with scientific studies. Crataegus monogyna is an example of “functional food” traditionally used all over South European countries. Objective- A complete chemical and bioactive characterization of flower buds, flowers, unripe, ripened and over ripened fruits was performed. Methodology- Chemical characterization included determination of proteins, fats, ash, and carbohydrates, particularly sugars by HPLC-RI, fatty acids by GC-FID, tocopherols by HPLC-fluorescence, phenolics, flavonoids, β-carotene and ascorbic acid, by spectrophotometric techniques. Bioactivity was evaluated through screening of antioxidant properties: radical scavenging effects, reducing power, and inhibition of lipid peroxidation. Results- Flowers revealed the highest tocopherols and ascorbic acid contents, as also the best n-6/n-3 fatty acids ratio. Over ripened fruits showed the highest levels of carbohydrates, sugars and SFA. Unripe fruits presented the highest PUFA contents with the best PUFA/SFA ratio, as also the highest levels of phenolics and the most promising antioxidant properties (EC50 < 20.83 µg/ml; even better than trolox). Conclusion- This study shows the potential of different parts of Crataegus monogyna as sources of several compounds, including nutrients and nutraceuticals. Moreover, it supports the documented nutritional and medicinal impact of this species.

2011Journal article

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Nutritional composition and bioactive properties of commonly consumed wild greens: Potential sources for new trends in modern diets

Publication . Pereira, Carla; Barros, Lillian; Carvalho, Ana Maria; Ferreira, Isabel C.F.R.

Beyond the composition of the usual macronutrients and micronutrients, it is important to provide information on the composition of bioactive compounds and antioxidant capacity of foods, particularly of wild species to regain them for nowadays dietary habits. Many greens are known as excellent sources of natural antioxidants, and consumption of fresh plants in the diet may contribute to the daily antioxidant intake. In the present study five leafy wild greens traditionally consumed (Borago officinalis, Montia fontana, Rorippa nasturtium-aquaticum, Rumex acetosella, Rumex induratus) were studied in order to document macronutrients, micronutrients and non-nutrients composition. R. induratus revealed the highest levels of sugars, ascorbic acid, tocopherols, lycopene, chlorophylls, flavonoids, and one of the highest antioxidant activity expressed as DPPH scavenging activity, B-carotene bleaching inhibition, and TBARS formation inhibition. R. nasturdium-aquaticum showed the healthier PUFA/SFA and n-6/n-3 ratios, and B. officinalis proved to be a source of Y-linolenic acid and other fatty acids from n-6 series that are precursors of mediators of the inflammatory response. The nutritional characteristics and antioxidant potential of these wild greens require reconsideration of their role in traditional as well as in contemporary diets. Furthermore, their extracts might find applications in the prevention of free radical-related diseases, as functional food formulations.

2011Journal article

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Low dose gamma-irradiation as a suitable solution for chestnut (Castanea sativa Miller) conservation: effects on sugars, fatty acids and tocopherols

Publication . Fernandes, Ângela; Antonio, Amilcar L.; Barros, Lillian; Barreira, João C.M.; Bento, Albino; Botelho, M. Luísa; Ferreira, Isabel C.F.R.

Along with dehydration, the development of insects and microorganisms is the major drawback in chestnut conservation. Irradiation has been regaining interest as an alternative technology to increase food products shelf-life. In the present work, the effects of low dose gamma irradiation on sugars, fatty acids and tocopherols composition of chestnuts stored at 4 ºC for different storage periods (0, 30 and 60 days) was evaluated. The irradiations were performed in a 60Co experimental equipment, for 1 h (0.27 +/- 0.04 kGy) and 2 h (0.54 +/- 0.04 kGy). Changes in sugars and tocopherols were determined by high performance liquid chromatography (HPLC) coupled to refraction index (RI) and fluorescence detections, respectively, while changes in fatty acids were analysed by gas-chromatography coupled to flame ionization detection (GC-FID). Regarding sugars composition, storage time proved to have higher effect than irradiation treatment. Fructose and glucose increased after storage, with the corresponding decrease of sucrose. Otherwise, tocopherols content was lower in non-irradiated samples, without a significant influence of storage. Saturated (SFA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids levels were not affected neither by storage nor irradiation. Nevertheless, some individual fatty acids concentrations were influenced by one of both factors, such as the increase of palmitic acid in irradiated samples or the decrease of oleic acid after 60 days of storage. Overall, the assayed irradiation doses seem to be a promising alternative treatment to increase chestnuts shelf-life, without affect the profile and composition in important nutrients.

2011Journal article

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Beef burger patties incorporated with Boletus edulis extracts: lipid peroxidation inhibition effects

Publication . Barros, Lillian; Barreira, João C.M.; Grangeia, Cátia; Batista, Cátia Emanuela Oliveira; Cadavez, Vasco; Ferreira, Isabel C.F.R.

The objective of this study was to analyse the lipid peroxidation inhibition in beef burgers after incorporation of Boletus edulis extracts in different concentrations. Beef burgers samples were stored for 8 days, and chemical and nutritional parameters, including the profile in free fatty acids, were evaluated. Furthermore, the inhibition of thiobarbituric acid reactive substances (TBARS) formation, free radical scavenging activity and reducing power were determined. Polyunsaturated fatty acids arachidonic (C20:4n6) and cis-5,8,11,14,17-eicosapentaenoic (C20:5n3) acids were protected in the presence of mushroom extract. The antioxidant potential increased with the amount of extract added to beef burgers, giving higher radical scavenging properties and TBARS inhibition capacity. These findings indicated that beef burgers patties were protected from lipid peroxidation in the presence of mushroom extract.

2011Journal article

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