IMPROVING SECONDARY METABOLITES PRODUCTION THROUGH IN VITRO CULTURE TECHNIQUE: CHEMICAL AND GENETIC CHARACTERIZATION OF EDIBLE PLANTS, BIOACTIVE PROPERTIES AND MICROENCAPSULATION OF PHENOLIC FRACTIONS

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Pyomelanin synthesis in alternaria alternata inhibits DHN-Melanin synthesis and decreases cell wall chitin content and thickness

Publication . Fernandes, Chantal; Mota, Marta; Barros, Lillian; Dias, Maria Inês; Ferreira, Isabel C.F.R.; Piedade, Ana P.; Casadevall, Arturo; Gonçalves, Teresa

The genus Alternaria includes several of fungi that are darkly pigmented by DHNmelanin. These are pathogenic to plants but are also associated with human respiratory allergic diseases and with serious infections in immunocompromised individuals. The present work focuses on the alterations of the composition and structure of the hyphal cell wall of Alternaria alternata occuring under the catabolism of L-tyrosine and L-phenylalanine when cultured in minimal salt medium (MM). Under these growing conditions, we observed the released of a brown pigment into the culture medium. FTIR analysis demonstrates that the produced pigment is chemically identical to the pigment released when the fungus is grown in MM with homogentisate acid (HGA), the intermediate of pyomelanin, confirming that this pigment is pyomelanin. In contrast to other fungi that also synthesize pyomelanin under tyrosine metabolism, A. alternata inhibits DHN-melanin cell wall accumulation when pyomelanin is produced, and this is associated with reduced chitin cell wall content. When A. alternata is grown in MM containing L-phenylalanine, a L-tyrosine percursor, pyomelanin is synthesized but only at trace concentrations and A. alternata mycelia display an albino-like phenotype since DHN-melanin accumulation is inhibited. CmrA, the transcription regulator for the genes coding for the DHN-melanin pathway, is involved in the down-regulation of DHN-melanin synthesis when pyomelanin is being synthetized, since the CMRA gene and genes of the enzymes involved in DHN-melanin synthesis pathway showed a decreased expression. Other amino acids do not trigger pyomelanin synthesis and DHN-melanin accumulation in the cell wall is not affected. Transmission and scanning electron microscopy show that the cell wall structure and surface decorations are altered in L-tyrosine- and L-phenylalanine-grown fungi, depending on the pigment produced. In summary, growth in presence of L-tyrosine and L-phenylalanine leads to pigmentation and cell wall changes, which could be relevant to infection conditions where these amino acids are expected to be available.

2021Journal article

Open access

Nutritional and chemical characterization of edible petals and corresponding infusions: Valorization as new food ingredients

Publication . Pires, Tânia C.S.P.; Dias, Maria Inês; Barros, Lillian; Ferreira, Isabel C.F.R.

Edible flowers provide new colours, textures and vibrancy to any dish, and apart from the “glam” factor, they can constitute new sources of bioactive compounds. In the present work, the edible petals and infusions of dahlia, rose, calendula and centaurea, were characterized regarding their nutritional value and composition in terms of hydrophilic and lipophilic compounds. Carbohydrates were the most abundant macronutrients, followed by proteins and ash. Fructose, glucose and sucrose were identified in all the petals and infusions. Rose petals and calendula infusions gave the highest content of organic acids, mainly due to the presence of malic and quinic acids, respectively. Polyunsaturated fatty acids predominated over saturated fatty acids, mainly due to the contr ibution of linoleic acid. Calendula presented the highest content in tocopherols, with a-tocopherol as the most abundant. These results highlight the interest of edible petals “as” and “in” new food products, representing rich sources of bioactive nutrients.

2017Journal article

Open access

Development of a new nutraceutical formulation containing microencapsulated polyphenolic extracts from wild Fragaria vesca L. vegetative parts

Publication . Dias, Maria Inês; Barros, Lillian; Oliveira, Beatriz; Santos-Buelga, Celestino; Barreiro, M.F.; Ferreira, Isabel C.F.R.

The microencapsulation of bioactive compounds and its applicability in food matrices arises to overcome many problems related with the use of free bioactives [l]. Natural bioactive extracts are increasingly used in this technique due to their synergistic and additive effects that can provide higher beneficiai effects [2]. The vegetative parts of Fragaria vesca L., wild strawberry, are being used as infüsion or decoction for their detoxifying and diuretic properties; the bioactivities reported for this plant could be correlated with the presence of several families of phenolic compounds such as, ellagic acid derivatives, flavonols and flavan 3-ols [3,4]. In the present study, the individual phenolic profile of hydroalcoholic and aqueous extracts ofwild F. vesca vegetative parts was established using HPLC-DAD/ESI-MS, and related to their antioxidant activity evaluated through several in vitro assays. Furthermore, the most bioactive extract, the infüsion form, was protected by microencapsulation through the atomization/coagulation technique using alginate as the wall material. Also, an applicability experiment was developed using k-carrageeaan gelatine as food matrix, in arder to explore new nutraceutical formulations for food applications. The aqueous preparations presented higher antioxidant activity that the hydromethanolic extracts in DPPH scavenging activity, reducing power, p-carotene bleaching inhibition and TBARS inhibition assays. It gave higher content of phenolic compounds, mainly flavonols and flavan-3-ols: (+)-catechin and quercetin 0-glucuronide, respectively, which can be correlated with the higher bioactivity observed m these extracts. The production of microspheres enriched with the infusion form of wild F. vesca was achieved with success using the atomization/coagulation techaique. The microspheres obtained showed, after FTIR analysis, the desired shape and size. The HPLC-DAD analysis of the coagulation water evidenced encapsulation efficiency dose to 95%. For the incorporation into the gelatme food matrix, high temperatures were used (dissolution of the k-carrageenan), but without affecting the shape and size ofthe enriched microspheres, preserving the bioactive extract. The antioxidant properties of the extract were preserved after microencapsulation, when compared with the free form that loses activity when incorporated in the gelatine matrix without protection. This is an innovative study on the development of nutraceuticals based on F. vesca extracts. Further studies will be required to establish a controlled release ofthe bioactive extract within the organism, using an in vitro gastrointestinal model.

2015Conference object

Open access

Flores comestíveis como fonte de nutrientes e compostos bioativos

Publication . Pires, Tânia C.S.P.; Dias, Maria Inês; Barros, Lillian; Ferreira, Isabel C.F.R.

Hoje em dia assiste-se a uma preocupação generalizada por parte dos consumidores em torno de uma alimentação mais cuidada que combine novos ingredientes com possíveis efeitos benéficos na saúde [1]. As flores comestíveis providenciam novas cores, texturas e um carisma próprio a variadíssimos pratos e, para além do seu efeito glamoroso, podem constituir fontes alternativas de compostos bioativos [2]. No presente trabalho, as pétalas comestíveis das plantas Dahlia mignon, Rosa canina L., Calendula officinalis L. e Centaurea cyanus L. (Fig. 1), fornecidas pela empresa RBR Foods (Portugal), foram caracterizadas em termos de macronutrientes, valor energético e perfil individual em ácidos gordos e tocoferóis (GC-FID e HPLCfluorescência, respetivamente). As pétalas e respetivas infusões foram ainda caracterizadas relativamente à sua composição em açúcares solúveis e ácidos orgânicos (HPLC-RI e HPLC-DAD, respetivamente). Os hidratos de carbono foram os macronutrientes mais abundantes, seguidos das proteínas e cinzas. Os ácidos gordos polinsaturados predominaram sobre os ácidos gordos saturados, principalmente devido à presença de ácido linoleico. As pétalas de C. officinalis apresentaram a maior concentração em tocoferóis, principalmente α-tocoferol. Relativamente aos açúcares, frutose, glucose e sacarose foram identificadas em todas as pétalas e respetivas infusões. As pétalas de rosa e a infusão de calêndula apresentaram maiores teores de ácidos orgânicos, principalmente devido à presença dos ácidos málico e quínico, respetivamente. Estes resultados demonstram o potencial de flores comestíveis para serem regularmente introduzidas na dieta alimentar.

2016Conference object

Open access

Nutritional and chemical characterization of food products enriched with biological produced fruits of Vaccinum myrtillus L

Publication . Pires, Tânia C.S.P.; Dias, Maria Inês; Barros, Lillian; Ferreira, Isabel C.F.R.

Vaccinum myrtillus L. belongs to Ericaceae family, being commonly known for its sweet small fruits: the blueberries. Widely consumed in fresh, these fruits are also used in jams and marmalades due to their digestive and hypoglycemic properties and also due to the presence of several bioactive compounds [!]. Therefore, it has become a very appealing matrix in the development of functional products that, beyond their nutritional properties, will add a long-term beneficial physiological/health effect [2]. In the present work, three novel blueberry based products developed by RBR Foods Company (Portugal), were characterized in terms of their nutritional and chemical properties: carbohydrates, ash, proteins, fat and energetic value (following official methods of food analysis), fatty acids profile (by CG-FID), soluble sugars (by HPLCRI), organic acids (by HPLC-DAD) and tocopherols (by HPLC-fluorescence). The products result from a mixture of the fruits with rose petals (PI), marigold petals (P2) and apple and goji berries (P3). The blueberry fruits were used as control sample. The nutritional profile of the novel products was very similar to the control sample: the carbohydrates were the most abundant macronutrient, followed by proteins and total fat. Regarding sugars, fructose, glucose and sucrose were identified in all the samples. P 1 and P2 didn't show significant differences in comparison to the control, however, P3 revealed a lower concentration of sugars. In terms of fatty acids composition, all the studied samples presented higher contents in polyunsaturated fatty acids, especially due to the contribution of linoleic and alinolenic acids. The results of tocopherols revealed that the control sample only presented two isoforrns of tocopherols, a- and y-tocopherol, being the same observed in P3. However, P 1 revealed the presence of all the isoforrns of tocopherols, while P2 was lacking otocopherol; which is related with the contribution of rose and marigold petals, respectively. The a-tocopherol isoforrn was the most abundant in all the studied samples. Overall, this work contributed to the nutritional characterization of novel blueberry based products and is a part of a wider project that aims the detailed study of these products, namely their potential to be used as functional foods.

2016Conference object

Open access