Loading...
41 results
Search Results
Now showing 1 - 10 of 41
- Cytotoxity induced by extracts of Pisolithustinctorius spores on human cancer and normal cell lines – evaluation of the anticancer potentialPublication . Alves, Ricardo; Preto, Marco; Oliveira, Rui S.; Martins, RosárioCancer is one of the most important causes of death and morbidity worldwide. According to the World Health Organization 8.2 million people have died from cancer in 2012. The treatment of this fast growing disease is regarded as a major challenge in health for the XXI century. Conventional anti-cancer therapy is usually aggressive to the patients due to systemic toxicity caused by lack of specificity of the chemotherapy drugs (Kidd, 2000). This has triggered the interest of the scientific community to search for new and more effective therapies, less aggressive than conventional treatments. Used since antiquity in oriental civilizations, fungi, in particular mushrooms have been shown to limit or reverse tumor growth (Kidd, 2000). Pisolithustinctorius (Basidiomycota) is a soil fungus with world-wide distribution that it known to form ectomycorrhizal symbioses in forest ecosystems (Kope & Fortin, 1990). The sporocarps of this fungus contain Pisosterol, a triterpene that has been shown to have antitumor activity against some cancer cell lines (Montenegro et al., 2004). Nevertheless, no studies have focused on the anticancer potential of other structures such as spores and thus the anticancer potential of P. tinctorius , remains largely unknown.
- Toxicity assessment of crude and partially purified extracts of marine Synechocystis and Synechococcus cyanobacterial strains in marine invertebratesPublication . Martins, Rosario; Fernandez, Nuria; Beiras, Ricardo; Vasconcelos, VítorAmong the Cyanoprokaryota, the genera Synechocystis and Synechococcus have rarely been studied with respect to potential toxicity. This is particularly true with marine environments where studies about the toxicity of cyanobacteria are restricted to filamentous forms at the warmer temperate and tropical regions and also to filamentous forms at cold seas such as the Baltic Sea. In this study, we describe the effects of cyanobacterial strains of the Synechocystis and Synechococcus genera isolated from the marine coast of Portugal, on marine invertebrates. Crude and partially purified extracts at a concentration of 100 mg/ml of freeze-dried material of the marine strains were tested for acute toxicity in nauplii of the brine shrimp Artemia salina, in the rotifer Brachionus plicatillis and in embryos of the sea urchin Paracentrotus lividus and the mussel Mytilus galloprovincialis. The cyanobacterial extracts, especially the crude extract, had an impact on A. salina nauplii. No significant toxic effects were registered against the rotifer. A negative impact of all strains was recorded on the embryonic development of the sea urchin, with toxic effects resulting in an inhibition of embryogenesis or development of smaller larvae. To the mussel embryos, the effects of cyanobacterial extracts resulted in a complete inhibition of embryogenesis. The results of all assays indicate that Synechocystis and Synechococcus marine strains contained toxic compounds to marine invertebrates.
- Hierridin B Isolated from a Marine Cyanobacterium Alters VDAC1, Mitochondrial Activity, and Cell Cycle Genes on HT-29 Colon Adenocarcinoma CellsPublication . Freitas, Sara; Martins, Rosario; Costa, Margarida; Leão, Pedro; Vitorino, Rui; Vasconcelos, Vitor; Urbatzka, RalphHierridin B was isolated from a marine cyanobacterium Cyanobium sp. strain and induced cytotoxicity selectively in HT-29 adenocarcinoma cells. The underlying molecular mechanism was not yet elucidated.
- Structure of Hierridin C, Synthesis of Hierridins B and C, and Evidence for Prevalent Alkylresorcinol Biosynthesis in PicocyanobacteriaPublication . Costa, Margarida; Sampaio-Dias, Ivo E.; Castelo-Branco, Raquel; Scharfenstein, Hugo; Rezende de Castro, Roberta; Silva, Artur; Schneider, Maria Paula C.; Araújo, Maria João; Martins, Rosario; Domingues, Valentina F.; Nogueira, Fátima; Camões, Vera; Vasconcelos, Vitor M.; Leão, Pedro N.Small, single-celled planktonic cyanobacteria are ubiquitous in the world's oceans yet tend not to be perceived as secondary metabolite-rich organisms. Here we report the isolation and structure elucidation of hierridin C, a minor metabolite obtained from the cultured picocyanobacterium Cyanobium sp. LEGE 06113. We describe a simple, straightforward synthetic route to the scarcely produced hierridins that relies on a key regioselective halogenation step. In addition, we show that these compounds originate from a type III PKS pathway and that similar biosynthetic gene clusters are found in a variety of bacterial genomes, most notably those of the globally distributed picocyanobacteria genera Prochlorococcus, Cyanobium and Synechococcus.
- Elucidating the mechanisms Involved in the cytotoxicity induced by marine cyanobacteria strains against the RKO colon carcinoma cell linePublication . Freitas, S.; Urbatzka, R.; Osório, H.; Costa, M.; Barros, Piedade; Vasconcelos, V.; Martins, RosárioCyanobacteria are known to synthesize secondary metabolites that may have potential as drugs for the treatment of human diseases such as cancer. Previous studies on marine cyanobacteria isolated from the Portuguese coast revealed strains of the picoplanktonic genera Cyanobium and Synechocystis as potential sources of anticancer compounds. The ethyl acetate fraction of the strains Cyanobium sp. LEGE06113 and the Synechocystis salina LEGE06155 was found to reduce cell viability of cancer cell lines. This work aimed to elucidate the mechanisms involved in the cytotoxicity of this strains in the colon adenocarcinoma cell line RKO by employing real-time PCR (RT-PCR) for genes involved in cell cycle and apoptosis, by flow cytometry for cell cycle and by two-dimensional gel electrophoresis for protein expression. RT-PCR results revealed differences in mRNA expression of genes CCNB1 (cell cycle) and BCL-2 (apoptosis). Flow cytometry results revealed a decrease in the G0/G1 and S phase and increased its number in the G2/M phase, which is in accordance with the lower expression of CCNB1. The proteomic results demonstrated different protein patterns comparing treatment groups with control. Proteins differentially regulated in exposed RKO cells were involved in cell cycle regulation, apoptosis, cell structure, protein regulation and cell metabolism. Although several of these proteins were identified in cells exposed to both cyanobacterial extracts, the data provides an indication that the cytotoxicity is induced by different toxic mechanisms in LEGE06113 and LEGE06155 fractions.
- Cyanobacterial diversity held in microbial biological resource centers as a biotechnological asset: the case study of the newly established LEGE culture collectionPublication . Ramos, Vitor; Morais, João; Castelo-Branco, Raquel; Pinheiro, Ângela; Martins, Joana; Regueiras, Ana; Pereira, Ana L.; Lopes, Viviana R.; Frazão, Bárbara; Gomes, Dina; Moreira, Cristiana; Costa, Maria Sofia; Brûle, Sébastien; Faustino, Silvia; Martins, Rosario; Saker, Martin; Osswald, Joana; Leão, Pedro N.; Vasconcelos, Vitor M.Cyanobacteria are a well-known source of bioproducts which renders culturable strains a valuable resource for biotechnology purposes. We describe here the establishment of a cyanobacterial culture collection (CC) and present the first version of the strain catalog and its online database (http://lege.ciimar.up.pt/). The LEGE CC holds 386 strains, mainly collected in coastal (48%), estuarine (11%), and fresh (34%) water bodies, for the most part from Portugal (84%). By following the most recent taxonomic classification, LEGE CC strains were classified into at least 46 genera from six orders (41% belong to the Synechococcales), several of them are unique among the phylogenetic diversity of the cyanobacteria. For all strains, primary data were obtained and secondary data were surveyed and reviewed, which can be reached through the strain sheets either in the catalog or in the online database. An overview on the notable biodiversity of LEGE CC strains is showcased, including a searchable phylogenetic tree and images for all strains. With this work, 80% of the LEGE CC strains have now their 16S rRNA gene sequences deposited in GenBank. Also, based in primary data, it is demonstrated that several LEGE CC strains are a promising source of extracellular polymeric substances (EPS). Through a review of previously published data, it is exposed that LEGE CC strains have the potential or actual capacity to produce a variety of biotechnologically interesting compounds, including common cyanotoxins or unprecedented bioactive molecules. Phylogenetic diversity of LEGE CC strains does not entirely reflect chemodiversity. Further bioprospecting should, therefore, account for strain specificity of the valuable cyanobacterial holdings of LEGE CC.
- Isolation of Hierridin B from a culturable Cyanobium sp. strain isolated from the Portuguese coastPublication . Leão, Pedro N.; Pereira, Alban R.; Costa, Margarida; Ramos, Vítor; Martins, Rosário; Gerwick, William H.; Vasconcelos, VitorCyanobacteria are a genetically diverse group of phototrophic prokaryotes. On a secondary metabolite perspective, however, filamentous and benthic forms have been the major sources of compounds isolated from these organisms. Nevertheless, unicellular free-living, planktonic cyanobacteria also contain enzymatic machinery for secondary metabolite biosynthesis.
- A natural oxadiazine isolated from cyanobacteria kills cancer cells in multicellular culture systems by impairing cellular respirationPublication . Sousa, Maria Lígia; Preto, Marco; Martins, Rosário; Vasconcelos, Vítor; Linder, Stig; Urbatzka, RalphCyanobacteria are versatile microorganisms that ubiquitously inhabit terrestrial and aquatic ecosystems. They adapt to external threats by mainly producing secondary metabolites. Therefore, cyanobacteria have been recognized as producer of natural products with potential biotechnological applications, such as bioplastics, antifouling, antibiotics, antiprotozoal or anticancer treatment.
- Cytotoxicity in L929 fibroblasts and inhibition of herpes simplex virus type 1 Kupka by estuarine cyanobacteria extractsPublication . Lopes, Viviana R.; Schmidtke, Michaela; Fernandes, Maria Helena; Martins, Rosario; Vasconcelos, VítorThe cyanobacteria are known to be a rich source of metabolites with a variety of biological activities in different biological systems. In the present work, the bioactivity of aqueous and organic (methanolic and hexane) crude extracts of cyanobacteria isolated from estuarine ecosystems was studied using different bioassays. The assessment of DNA damage on the SOS gene repair region of mutant PQ37 strain of Escherichia coli was performed. Antiviral activity was evaluated against influenza virus, HRV-2, CVB3 and HSV-1 viruses using crystal violet dye uptake on HeLa, MDCK and GMK cell lines. Cytotoxicity evaluation was performed with L929 fibroblasts by MTT assay. Of a total of 18 cyanobacterial isolates studied, only the crude methanolic extract of LEGE 06078 proved to be genotoxic (IF > 1.5) in a dose-dependent manner and other four were putative candidates to induce DNA damage. Furthermore, the crude aqueous extract of LEGE 07085 showed anti- herpes type 1 activity (IC50 = 174.10 μg dry extract mL−1) while not presenting any cytotoxic activity against GMK cell lines. Of the 54 cyanobacterial extracts tested, only the crude methanolic and hexane ones showed impair on metabolic activity of L929 fibroblasts after long exposure (48–72 h). The inhibition of HSV-1 and the strong cytotoxicity against L929 cells observed emphasizes the importance of evaluating the impact of those estuarine cyanobacteria on aquatic ecosystem and on human health. The data also point out their potential application in HSV-1 treatment and pharmacological interest.
- Screening the toxicity of selected personal care products using embryo bioassays: 4-MBC, propylparaben and triclocarbanPublication . Torres, Tiago; Cunha, Isabel; Martins, Rosario; Santos, MiguelRecently, several emerging pollutants, including Personal Care Products (PCPs), have been detected in aquatic ecosystems, in the ng/L or µg/L range. Available toxicological data is limited, and, for certain PCPs, evidence indicates a potential risk for the environment. Hence, there is an urgent need to gather ecotoxicological data on PCPs as a proxy to improve risk assessment. Here, the toxicity of three different PCPs (4-Methylbenzylidene Camphor (4-MBC), propylparaben and triclocarban) was tested using embryo bioassays with Danio rerio (zebrafish) and Paracentrotus lividus (sea urchin). The No Observed Effect Concentration (NOEC) for triclocarban was 0.256 µg/L for sea urchin and 100 µg/L for zebrafish, whereas NOEC for 4-MBC was 0.32 µg/L for sea urchin and 50 µg/L for zebrafish. Both PCPs impacted embryo development at environmentally relevant concentrations. In comparison with triclocarban and 4-MBC, propylparaben was less toxic for both sea urchin (NOEC = 160 µg/L) and zebrafish (NOEC = 1000 µg/L). Overall, this study further demonstrates the sensitivity of embryo bioassays as a high-throughput approach for testing the toxicity of emerging pollutants.