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Projeto de investigação
CNC.IBILI - Centro de Neurociências e Biologia Celular
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Secondary metabolites (essential oils) from sand-dune plants induce cytotoxic effects in cancer cells
Publication . Beeby, Ellie; Magalhães, Mariana; Poças, Juliana; Collins, Thomas; Lemos, Marco F.L.; Barros, Lillian; Ferreira, Isabel C.F.R.; Cabral, Célia; Pires, Isabel M.
Ethnopharmacological relevance: Despite advances in modern therapeutic strategies, cancer remains the second
leading cause of death worldwide. Therefore, there is a constant need to develop more efficient anticancer
targeting strategies. The anticancer therapeutic proprieties of medicinal plants and their bioactive compounds
have been reported for several years, making natural extracts and/or compounds derived from these a promising
source of novel anticancer agents. Sand dune plants are subjected to severe environmental stresses, leading to the
development of adaptations, including the production of secondary metabolites with a wide range of bioactivities,
such as: anti-inflammatory, analgesic, antiseptic, hypoglycaemic, hypotensive, antinociceptive, antioxidant
and anticancer.
Aim of the study: The anticancer potential of sand dune plants remains under-investigated, so this research describes
the characterisation of the composition of bioactive EOs from sand-dune plants of Peniche (Portugal), and
assessment of their activity in vitro and potential mechanism of action.
Materials and methods: EOs were extracted from six sand-dune species of plants from Peniche sand dunes: Crithmum
maritimum L., Seseli tortuosum L., Artemisia campestris subsp. maritima (DC.) Arcang., Juniperus phoenicea var. turbinata
(Guss.) Parl., Otanthus maritimus (L.) Hoffmanns. & Link, and Eryngium maritimum L.. EOs composition was fully
characterised chemically using Gas Chromatography-Mass Spectrometry (GC-MS). The assessment of anticancer
activity and mechanism of action was performed in vitro using breast and colorectal cancer 2D and 3D spheroid cell
line models, through cell proliferation assay, western blotting analysis, and cell cycle analysis.
Results: EOs from the majority of the species tested (S. tortuosum, A. campestris subsp. maritima, O. maritimus, and E.
maritimum) were mainly composed by hydrocarbon compounds (sequisterpenes and monoterpenes), showing antiproliferative
activity in both 2D and 3D models. EO extracted from S. tortuosum and O. maritimus were identified as
having the lowest IC50 values for both cell lines when compared with the other species tested. Furthermore, this
antiproliferative activity was associated with increased p21 expression and induction of apoptosis.
Conclusions: The present study suggests that EOs extracted from S. tortuosum and O. maritimus present promising
cytotoxic properties. Further evaluation of the extracts and their key components as potential anticancer agents
should therefore be explored.
The antifungal activity of extracts of Osmundea pinnatifida, an edible seaweed, indicates its usage as a safe environmental fungicide or as a food additive preventing post-harvest fungal food contamination
Publication . Silva, Paulo; Fernandes, Chantal; Barros, Lillian; Ferreira, Isabel C.F.R.; Pereira, Leonel; Gonçalves, Teresa
In the present work, we explored the antifungal activity of the wild edible seaweed Osmundea pinnatifida (Rhodophyta) collected from the Portuguese coast, which is used as a food seasoning in Scotland, Ireland and Portugal. We performed a sequential extraction of the seaweed components with methanol, dichloromethane and n-hexane. These extracts showed an antifungal activity against Alternaria infectoria and Aspergillus fumigatus. The n-hexane fraction of the seaweed inhibited the sporulation of Alternaria infectoria at 30 μg mL −1 and induced a statistically significant decrease in β-glucan content. Furthermore, liquid cultures of Aspergillus fumigatus supplemented with 10 μg mL −1 of the n-hexane fraction showed abnormal conidiophores, completely devoid of phialides and conidia associated with a decrease of 18.3% in the chitin content. The n-hexane fraction analysis by GC-MS revealed that it includes palmitic acid (29.6%), phytol isomer 1 (12.8%), oleic acid (9.6%), stearic acid (6.2%) and D-(−)-tagatofuranose (4.1%), among other compounds present at lower concentrations. The present study reveals Osmundea pinnatifida as a promising source of biologically active compounds inhibiting fungal growth and conidiation, the main dispersal mechanism of filamentous fungi as Aspergillus fumigatus and Alternaria alternata, revealing its utility both as an environmental fungicide against fungal diseases and as a food preservative against fungal post-harvest food contamination.
In vitro macrophage nitric oxide production by Pterospartum tridentatum (L.) Willk. inflorescence polysaccharides
Publication . Martins, Vitor Manuel Ramalheira; Simões, Joana A.; Ferreira, Isabel C.F.R.; Cruz, Maria T.; Domingues, Maria R.M.; Coimbra, Manuel A.
Pterospartum tridentatum (L.) Willk. decoctions of dried inflorescences are used in Portugal due to their claimed beneficial properties for various health disorders. To disclose the potential contribution of its polysaccharides to health benefits, in this work, hot water extracts from P. tridentatum inflorescences were prepared and fractionated by ethanol precipitation and anion exchange chromatography. The fraction rich in acetylated galactomannans evidenced an increase in nitric oxide (NO) production by macrophages. This activity decreased 60–75% after saponification, confirming that acetylation is an important structural feature for this biological property. In addition, the treatment of pectic polysaccharides with endo-polygalacturonase showed that type-I and type-II arabinogalactans, as well as low molecular weight galacturonans and xyloglucans, may also contribute to macrophage NO production. Thus, the polysaccharides present in P. tridentatum dried inflorescences may contribute to the health beneficial properties frequently attributed to the decoctions of this plant.
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.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
5876
Número da atribuição
UID/NEU/04539/2013