O digital storytelling como técnica de marketing : os casos Repetto, Carel e Josefinas

O presente trabalho de investigação tem como objectivo compreender de que forma o storytelling digital pode ser uma mais valia para as marcas. Procuramos circunscrever a análise teórica ao campo do stortytelling, branding, marketing de conteúdos e storytelling digital para que se possa construir uma base científica para posterior análise empírica das marcas Repetto, Carel e Josefinas. Baseando a investigação científica no campo interpretativista, procurou-se perceber como é que storytelling pode ser indissociável da comunicação humana e como pode atuar no contexto publicitário digital. A análise qualitativa de texto é a abordagem escolhida para a análise dos estudos de caso e procurou determinar se as marcas recorrem ao storytelling digital enquanto técnica de marketing de conteúdos. Procurou-se também fazer uma análise comparativa entre as três marcas para averigurar se alguma usa o storytelling de forma mais acentuada do que as restantes.This research work aims at understanding the ways in which digital storytelling can be a valuable asset for brands. Our theoretical analysis focuses on the fields of storytelling, branding, content marketing and digital storytelling in order to build up scientific grounds on which to sustain the empirical analysis of the Repetto, Carel and Josefinas brands. By focusing the scientific research on the interpretative field, we will attempt to understand how can storytelling be connected to human communication and how it can act in a digital advertisement context. Qualitative text analysis is the chosen approach for the case study analysis and it will attempt to show whether brands use digital storytelling as a content marketing technique. A comparative analysis of all three brands is also performed, in order to investigate whether any of them resorts to storytelling more often

Structure and ligand-based design of P-glycoprotein inhibitors: a historical perspective

Computer-assisted drug design (CADD) is a valuable approach for the discovery of new chemical entities in the field of cancer therapy. There is a pressing need to design and develop new, selective, and safe drugs for the treatment of multidrug resistance (MDR) cancer forms, specifically active against P-glycoprotein (P-gp). Recently, a crystallographic structure for mouse P-gp was obtained. However, for decades the design of new P-gp inhibitors employed mainly ligand-based approaches (SAR, QSAR, 3D-QSAR and phar macophore studies), and structure-based studies used P-gp homology models. However, some of those results are still the pillars used as a starting point for the design of potential P-gp inhibitors. Here, pharmacophore mapping, (Q)SAR, 3D-QSAR and homology modeling, for the discovery of P-gp inhibitors are reviewed. The importance of these methods for understanding mechanisms of drug resistance at a molecular level, and design P-gp inhibitors drug candidates are discussed. The examples mentioned in the review could provide insights into the wide range of possibilities of using CADD methodologies for the discovery of efficient P-gp inhibitors.info:eu-repo/semantics/publishedVersio

Multidrug resistance reversal effects of aminated thioxanthones and interaction with cytochrome P450 3A4

Aminated thioxanthones have recently been described as dual-acting agents: growth inhibitors of leukemia cell lines and P-glycoprotein (P-gp) inhibitors. To evaluate the selectivity profile of thioxanthones as inhibitors of multidrug resistance (MDR), their interaction with other ABC transporters, which were found to have a strong correlation with multidrug resistance, such as multidrug resistant proteins 1 (MRP1), 2 (MRP2) and 3 (MRP3) and breast cancer resistance protein (BCRP) was also evaluated. The interaction of thioxanthones with cytochrome P450 3A4 (CYP3A4) together with the prediction of their binding conformations and metabolism sites was also investigated. Methods. The UIC2 monoclonal antibody-labelling assay was performed using P-gp overexpressing leukemia cells, K562Dox, incubated with eight thioxanthonic derivatives, in order to confirm their P-gp inhibitory activity. A colorimetric-based ATPase assay using membrane vesicles from mammalian cells overexpressing a selected human ABC transporter protein (P-gp, MRP1, MRP2, MRP3, or BCRP) was performed. To verify if some of the thioxanthonic derivatives were substrates or inhibitors of CYP3A4, a luciferin-based luminescence assay was performed. Finally, the in silico prediction of the most probable metabolism sites and docking studies of thioxanthones on CYP3A4 binding site were investigated. Results. Thioxanthones interacted not only with P-gp but also with MRP and BCRP transporters. These compounds also interfere with CYP3A4 activity in vitro, in accordance with the in silico prediction. Conclusion. Thioxanthonic derivatives are multi-target compounds. A better characterization of the interactions of these compounds with classical resistance mechanisms may possibly identify improved treatment applications.info:eu-repo/semantics/publishedVersio

New uses for old drugs: pharmacophore‐based screening for the discovery of P‐glycoprotein inhibitors

P-glycoprotein (P-gp) is one of the best character ized transporters responsible for the multidrug resistance phenotype exhibited by cancer cells. Therefore, there is widespread interest in eluci dating whether existing drugs are candidate P-gp substrates or inhibitors. With this aim, a pharma cophore model was created based on known P-gp inhibitors and it was used to screen a database of existing drugs. The P-gp modulatory activity of the best hits was evaluated by several methods such as the rhodamine-123 accumulation assay using K562Dox cell line, and a P-gp ATPase activ ity assay. The ability of these compounds to enhance the cytotoxicity of doxorubicin was assessed with the sulphorhodamine-B assay. Of the 21 hit compounds selected in silico, 12 were found to significantly increase the intracellular accumulation of Rhodamine-123, a P-gp substrate. In addition, amoxapine and loxapine, two tetracy clic antidepressant drugs, were discovered to be potent non-competitive inhibitors of P-gp, causing a 3.5-fold decrease in the doxorubicin GI50 in K562Dox cell line. The overall results provide important clues for the non-label use of known drugs as inhibitors of P-gp. Potent inhibitors with a dibenzoxazepine scaffold emerged from this study and they will be further investigated in order to develop new P-gp inhibitors.info:eu-repo/semantics/publishedVersio

Dual inhibitors of P-glycoprotein and tumor cell growth: (re)discovering thioxanthones

For many pathologies, there is a crescent effort to design multiple ligands that interact with a wide variety of targets. 1-Aminated thioxanthone derivatives were synthesized and assayed for their in vitro dual activity as antitumor agents and P-glycoprotein (P-gp) inhibitors. The approach was based on molecular hybridization of a thioxanthone scaffold, present in known antitumor drugs, and an amine, described as an important pharmacophoric feature for P-gp inhibition. A rational approach using homology modeling and docking was used, to select the molecules to be synthesized by conventional or microwave-assisted Ullmann C–N cross-coupling reaction. The obtained aminated thioxanthones were highly effective at inhibiting P-gp and/or causing growth inhibition in a chronic myelogenous leukemia cell line, K562. Six of the aminated thioxanthones had GI50 values in the K562 cell line below 10 mM and 1-{[2-(diethylamino)ethyl]amino}-4-propoxy-9H-thioxanthen-9-one (37) had a GI50 concentration (1.90 mM) 6-fold lower than doxorubicin (11.89 mM) in the K562Dox cell line. The best P-gp inhibitor found was 1-[2-(1H-benzimidazol-2-yl)ethanamine]-4-propoxy-9H-thioxanthen-9-one (45), which caused an accumulation rate of rhodamine-123 similar to that caused by verapamil in the K562Dox resistant cell line, and a decrease in ATP consumption by P-gp. At a concentration of 10 mM, compound 45 caused a decrease of 12.5-fold in the GI50 value of doxorubicin in the K562Dox cell line, being 2-fold more potent than verapamil. From the overall results, the aminated thioxanthones represent a new class of P-gp inhibitors with improved efficacy in sensitizing a resistant P-gp overexpressing cell line (K562Dox) to doxorubicin.info:eu-repo/semantics/publishedVersio

Design and synthesis of new inhibitors of p53–MDM2 interaction with a chalcone scaffold

The virtual screening of a library of chalcone derivatives led us to the identification of potential new MDM2 ligands. The chalcones with the best docking scores obeying the Lipinski rule of five were subsequently prepared by base-catalyzed aldol reactions. The activity of these compounds as inhibitors of p53–MDM2 interaction was investigated using a yeast-based screening assay. Using this approach two chalcones (3 and 4) were identified as putative small molecule inhibitors of p53–MDM2 interaction. The activity of both chalcones was further investigated in a panel of human tumor cells. Chalcones 3 and 4 revealed a pronounced tumor cell growth inhibitory effect on tumor cell lines. Additionally, chalcone 4 caused alterations in the cell cycle profile, induced apoptosis and increased the levels of p53, p21 and PUMA proteins in NCI-H460 cells. Computational docking studies allowed to predict that, like nutlin-3A (a well-known small-molecule inhibitor of p53–MDM2 interaction), chalcones 3 and 4 bind to the p53-binding site of MDM2. The results here presented will be valuable for the structure-based design of novel and potent p53–MDM2 inhibitors.This research was partially supported by the Strategic Funding UID/Multi/04423/2013 , ERDF , COMPETE , and FCT under the projects PTDC/MAR-BIO/4694/2014, and INNOVMAR – Innovation and Sustainability in the Management and Exploitation of Marine Resources, reference NORTE-01-0145-FEDER-000035 , Research Line NOVELMAR . This work also received financial support from the European Union (FEDER funds POCI/01/0145/FEDER/007265) and National Funds (FCT/MEC, Fundação para a Ciência e Tecnologia and Ministério da Educação e Ciência) under the Partnership Agreement PT2020 UID/QUI/50006/2013 and the FCT project PTDC/DTP-FTO/1981/2014, “PEst-C/SAU/LA0003/2013”, “NORTE-07-0162-FEDER-00018 – Contributos para o reforço da capacidade do IPATIMUP enquanto actor do sistema regional de inovação” and NORTE-07-0162-FEDER-000067 – Reforço e consolidação da capacidade infraestrutural do IPATIMUP para o sistema regional de inovação”, both supported by ON.2 – O Novo Norte, through FEDER funds under the QREN. IPATIMUP integrates the i3S Research Unit, which is partially supported by FCT. The authors also thank FCT for the grants of R.T. Lima ( SFRH/BPD/68787/2010 ), J. Soares ( SFRH/BD/78971/2011 ), and S. Gomes ( SFRH/BD/96189/2013 ; Doctoral Programme BiotechHealth), L. Raimundo ( PD/BI/113926/2015 , Doctoral Programme BiotechHealth)

Insights into the in vitro antitumor mechanism of action of a new pyranoxanthone

Naturally occurring xanthones have been docu mented as having antitumor properties, with some of them presently undergoing clinical trials. In an attempt to improve the biological activities of dihydroxyxanthones, prenylation and other mole cular modifications were performed. All the com pounds reduced viable cell number in a leukemia cell line K-562, with the fused xanthone 3, 4-dihydro-12-hydroxy-2,2-dimethyl-2H,6H-pyrano[3, 2-b]xanthen-6-one (5) being the most potent. The pyranoxanthone 5 was particularly effective in additional leukemia cell lines (HL-60 and BV-173). Furthermore, the pyranoxanthone 5 decreased cel lular proliferation and induced an S-phase cell cycle arrest. In vitro, the pyranoxanthone 5 increased the percentage of apoptotic cells which was confirmed by an appropriate response at the protein level (e.g., PARP cleavage). Using a com puter screening strategy based on the structure of several anti- and pro-apoptotic proteins, it was verified that the pyranoxanthone 5 may block the binding of anti-apoptotic Bcl-xL to pro-apoptotic Bad and Bim. The structure-based screening revealed the pyranoxanthone 5 as a new scaffold that may guide the design of small molecules with better affinity profile for Bcl-xL.info:eu-repo/semantics/publishedVersio

Glycoengineered nanoparticles enhance the delivery of 5-fluoroucil and paclitaxel to gastric cancer cells of high metastatic potential

Gastric cancer is the third leading cause of cancer-related death worldwide, with half of patients developing metastasis within 5 years after curative treatment. Moreover, many patients cannot tolerate or complete systemic treatment due severe side-effects, reducing their effectiveness. Thus, targeted therapeutics are warranted to improve treatment outcomes and reduce toxicity. Herein, poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with 5-fluorouracil (5-FU) and paclitaxel were surface-functionalized with a monoclonal antibody targeting sialyl-Lewis A (sLeA), a known glycan mediating hematogenous metastasis. Nanoparticles, ranging from 137 to 330 nm, enabled the controlled release of cytotoxic drugs at neutral and acid pH, supporting potential for intravenous and oral administration. Nanoencapsulation also reduced the initial toxicity of the drugs against gastric cells, suggesting it may constitute a safer administration vehicle. Furthermore, nanoparticle functionalization significantly enhanced targeting to sLeA cells in vitro and ex vivo (over 40% in comparison to non-targeted nanoparticles). In summary, a glycoengineered nano-vehicle was successfully developed to deliver 5-FU and paclitaxel therapeutic agents to metastatic gastric cancer cells. We anticipate that this may constitute an important milestone to establish improved targeted therapeutics against gastric cancer. Given the pancarcinomic nature of the sLeA antigen, the translation of this solution to other models may be also envisaged.publishe

Discovery of a new small-molecule inhibitor of p53–MDM2 interaction using a yeast-based approach

The virtual screening of a library of xanthone derivatives led us to the identification of potential novel MDM2 ligands. The activity of these compounds as inhibitors of p53–MDM2 interaction was investigated using a yeast phenotypic assay, herein developed for the initial screening. Using this approach, in association with a yeast p53 transactivation assay, the pyranoxanthone (3,4-dihydro-12- hydroxy-2,2-dimethyl-2H,6H-pyrano[3,2-b]xanthen-6-one) (1) was identified as a putative small molecule inhibitor of p53–MDM2 interaction. The activity of the pyranoxanthone 1 as inhibitor of p53–MDM2 interaction was further investigated in human tumor cells with wild-type p53 and overexpressed MDM2. Notably, the pyranoxanthone 1 mimicked the activity of known p53 activators, leading to p53 stabilization and activation of p53- dependent transcriptional activity. Additionally, it led to increased protein levels of p21 and Bax, and to caspase-7 cleavage. By computational docking studies, it was predicted that, like nutlin-3a, a known small-molecule inhibitor of p53–MDM2 interaction, pyranoxanthone 1 binds to the p53-binding site of MDM2. Overall, in this work, a novel small-molecule inhibitor of p53–MDM2 interaction with a xanthone scaffold was identified for the first time. Besides its potential use as molecular probe and possible lead to develop anticancer agents, the pyranoxanthone 1 will pave the way for the structure-based design of a new class of p53–MDM2 inhibitors.info:eu-repo/semantics/publishedVersio

Sulfated small molecules targeting EBV in Burkitt lymphoma: from in silico screening to the evidence of in vitro effect on viral episomal DNA

Epstein–Barr virus (EBV) infects more than 90% of the world population. Following primary infection, Epstein– Barr virus persists in an asymptomatic latent state. Occasionally, it may switch to lytic infection. Latent EBV infection has been associated with several diseases, such as Burkitt lymphoma (BL). To date, there are no available drugs to target latent EBV, and the existing broad-spec trum antiviral drugs are mainly active against lytic viral infection. Thus, using computational molecular docking, a virtual screen of a library of small molecules, including xanthones and flavonoids (described with potential for antiviral activity against EBV), was carried out targeting EBV proteins. The more interesting molecules were selected for further computational analysis, and sub sequently, the compounds were tested in the Raji (BL) cell line, to evaluate their activity against latent EBV. This work identified three novel sulfated small molecules capable of decreasing EBV levels in a BL. Therefore, the in silico screening presents a good approach for the development of new anti-EBV agents.info:eu-repo/semantics/publishedVersio