Browsing by Author "Skhiri, Fethia"
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- Incorporation of tocopherol-rich extracts from mushroom mycelia into yogurtPublication . Bouzgarrou, Chaima; Amara, Khira; Reis, Filipa S.; Barreira, João C.M.; Skhiri, Fethia; Chatti, Noureddine; Martins, Anabela; Barros, Lillian; Ferreira, Isabel C.F.R.Consumers are well-informed about food additives and it is likely that they prefer natural additives over their synthetic analogues. Antioxidants represent a major class of food preservatives, among which tocopherols stand out as one of the most important examples. Interestingly, these compounds are present in relevant amounts in the mycelia of in vitro cultured mushrooms. Accordingly, the mycelia from Ganoderma lucidum, Pleurotus ostreatus and Pleurotus eryngii were used as alternative sources of tocopherols. These extracts were incorporated into different yogurt formulations, which were further compared among each other and with yogurts containing commercial α-tocopherol (E307), regarding their nutritional parameters, fatty acid profile and antioxidant activity. The proposed approach was validated as an effective functionalization strategy, particularly in the case of the G. lucidum mycelium, which showed the highest antioxidant potential, most likely as a result of its tocopherol profile. Furthermore, yogurts prepared with each mycelium extract allowed maintaining the nutritional properties observed in the “blank” yogurt formulation.
- Nutritional values, chemical characterization and cytotoxicity in human tumor cell lines of desert trufflesPublication . Amara, Khira; Reis, Filipa S.; Barros, Lillian; Skhiri, Fethia; Martins, Anabela; Ferreira, Isabel C.F.R.Mushrooms are widely appreciated for their nutritional value, as well as for their health promoting properties [1,2]. Due to their proven bioactive potential, their application in food (e.g., incorporation of mushroom extracts in food products and functional foods) and pharmaceutical (e.g., nutraceuticals and food supplements incorporating mushrooms) industries, or the cosmetics industry (e.g., antiaging products) has been explored [3-5]. The present work intends to determine the chemical and nutritional composition, as also to evaluate the cytotoxicity of samples from a mushroom genus commonly known as desert truffles – Terfezia. To this end, three different species were studied, namely Terfezia arenaria (Moris) Trappe, Terfezia magnusii Mattir., and Terfezia leptoderma Tul. The nutritional value (protein, fat, carbohydrates and energetic value) of the species was evaluated following standard procedures, and their content in hydrophilic compounds (e.g., soluble sugars, phenolic and other organic acids) and lipophilic compounds (e.g., fatty acids and tocopherols) was assessed by chromatographic techniques (High Performance Liquid Chromatography and Gas Chromatography). The cytotoxic potential of the samples was also evaluated, testing the mushroom species against a panel of human tumor cell lines (MCF7- breast carcinoma, HeLa- cervical carcinoma, NCI-H460- non-small cell lung carcinoma and HepG2- hepatocellular carcinoma) and against porcine liver primary cells (PLP2). All samples proved to have high contents in carbohydrates and proteins, being low fat products. Mannitol and trehalose were the main sugars found, being also present bioactive phenolic acids. Among the lipophilic compounds, linoleic, oleic and plamitic acids were the major fatty acids present in the samples, together with different tocopherol vitamers. None of the samples showed cytotoxicity against non-tumor cells being in course the bioassays with human tumor cell lines. Overall, desert truffles proved to be highly nutritional species with bioactive compounds and potential to be used as cytotoxic agents.
- A prospective study on bioactive properties of wild mushrooms mycelium grown in vitro under different conditionsPublication . Souilem, Fedia; Barros, Lillian; Skhiri, Fethia; Ferreira, Isabel C.F.R.; Martins, AnabelaWild mushrooms have been extensively studied for their value as sources of high quality nutrients and of powerful physiologically bioactive compounds [1,2]. The present study was designed to evaluate the in vitro development of two wild edible mushroom species: Pleurotus eryngii (DC.) Quél. and Suillus belinii (Inzenga) Watling, by testing different solid (Potato Dextrose Agar medium –PDA and Melin-Norkans medium- MMN) and liquid culture media (Potato dextrose broth- PDB and Melin-Norkans medium- MMN). Each strain of mushroom produces a special type of mycelium and this range of characteristics varies in form, color and growth rate. S. bellinii presents a pigmented and rhizomorphic mycelia, whereas, P. eryngii has depigmented and cottony mycelia. The mycelium isolated and grown in PDA showed a faster radial growth compared to the mycelium isolated and grown in both solid and liquid incomplete MMN medium. P. eryngii exhibited a rapid growth and a higher mycelia biomass in both medium compared to S. belinii. Moreover, the obtained mycelia will be characterized in terms of well-recognized bioactive compounds namely, phenolic acids and mycosterols (mainly ergosterol), by using high performance liquid chromatography coupled to diode array and ultraviolet detectors, respectively. These compounds will be correlated to mycelia bioactivity: i) antioxidant activity, evaluated through free radicals scavenging activity, reducing power and lipid peroxidation inhibition in vitro assays; ii) anti-inflammatory activity, assessed through nitric oxide production inhibition in murine macrophages (RAW 264.7 cell line); iii) cytotoxic activity, evaluated either in human tumor cell lines (MCF-7- breast adenocarcinoma, NCIH460- non-small cell lung cancer, HeLa- cervical carcinoma and HepG2- hepatocellular carcinoma) as also in a non-tumor porcine primary liver cells culture established in-house (PLP2). Overall, our expectation is that the bioactive formulations obtained by in vitro culture can be applied as nutraceuticals or incorporated in functional foods.
- Utilização do micélio de Ganoderma lucidum para obtenção de extratos ricos em tocoferóis para aplicação como antioxidantes alimentaresPublication . Reis, Filipa S.; Caleja, Cristina; Amara, Khira; Barreira, João C.M.; Martins, Anabela; Skhiri, Fethia; Barros, Lillian; Ferreira, Isabel C.F.R.Atualmente, os consumidores estão mais bem informados acerca dos aditivos presentes nas matrizes alimentares e, cada vez mais, se encontra uma preferência por alternativas naturais relativamente aos análogos artificiais [1]. Os cogumelos sao consumidos em todo o mundo e são considerados alimentos funcionais devido a sua constituição química, rica em compostos bioativos, nomeadamente em tocofer6is [2]. Os tocofer6is sao poderosos antioxidantes que podem ser explorados coma aditivos naturais de alimentos, de forma a substituir os análogos artificiais utilizados extensivamente. Com estes aspetos em mente, e com a evidencia de que a cultura in vitro de micélio de cogumelos promove a produção de tocoferóis, o objetivo deste trabalho foi incorporar em iogurte natural, um extrato rico em tocofer6is obtido a partir da espécie Ganoderma lucidum (Curtis) P. Karst. Os níveis de tocofer6is foram determinados por técnicas cromatográficas, nomeadamente por cromatografia liquida de alta eficiência acoplada a um detetor de fluorescência (HPLC fluorescência). Posteriormente, o extrato enriquecido em tocofer6is obtido do micélio foi incorporado em iogurte natural avaliando-se o potencial antioxidante do extrato (antes da incorporação) e dos iogurtes (apóss incorporação), a fim de estudar o seu potencial como antioxidante alimentar. Foram avaliadas a atividade captadora de radicais 2,2-difenil-1-picrilhidrazilo (DPPH) e o poder redutor. Foi também estudada a eficácia do extrato rico em tocoferóis coma antioxidante alimentar, na preservação das propriedades nutricionais da matriz alimentar estudada. Estes estudos foram realizados comparando os parâmetros nutricionais de quatro formulações de iogurtes: i) iogurte controlo; ii) iogurte com sorbato de potássio E202; iii) iogurte com α-tocoferol - E307; e iv) iogurte com extrato rico em tocoferóis obtido do micélio de G. lucidum. A analise química mostrou que o micélio produzido in vitro e particularmente rico em α-tocoferol (272 j..lg/g de extrato) e 6-tocoferol (362 j..lg/g de extrato), apresentando um total de 717 j..lg de tocofer6is/g extrato. 0 micélio apresentou capacidade de captação de radicais DPPH (EC50 = 10,4 mg/ml), demonstrando ainda maior poder redutor (EC50 = 0,32 mg/ml). As formulações de iogurte com maior atividade antioxidante pertenceram ao grupo incorporado com o aditivo atocoferol e com o extrato rico em tocofer6is obtido do micélio de G. lucidum . Contudo, não foram observadas diferenças significativas entre 0 e 7 dias, particularmente no iogurte incorporado com extrato de micélio de G. lucidum. Atendendo aos valores da atividade antioxidante, pode concluir-se que os iogurtes incorporados com α-tocoferol ou com o extrato rico em tocofer6is obtido a partir do micélio de G. lucidum, foram os mais eficazes. Em geral, o micélio de G. lucidum pode, de facto, ser considerado coma uma potencial fonte de tocoferóis que podem ser introduzidos em alimentos como antioxidantes lipofflicos.