59 research outputs found
Monitoring of a slaughterhouse wastewater treatment plant – case study
O presente trabalho teve como objetivo caracterizar as águas residuais produzidas num matadouro, determinar as eficiências do processo de tratamento e propor medidas de melhoria. Da caracterização das águas residuais constatou-se que o efluente final cumpriu com os valores limite de emissão, exceto para o fósforo. De um modo geral, obtiveram-se eficiências de remoção dos poluentes superiores a 73%. Em relação aos parâmetros operacionais, verificou-se que o valor de F/M, entre 0,05 e 0,15 kgCBO5.kg-1MLVSS.d-1, é importante para aumentar a eficiência do processo. Aumentando a quantidade de coagulante e floculante a adicionar nas DAF’s, ocorrerá uma maior produção de lamas e consequente remoção de fósforo. Constatou-se que a manutenção adequada da purga de lamas permite a redução da biomassa no reator e aumenta a razão F/M.The present work aims to characterize the slaughterhouse wastewater treatment, calculate the treatment efficiency and recommend improvement measures. From the wastewater characterization it was noted that the final effluent complies with the emission limit values, except for phosphorus. Overall, removal efficiencies obtained for pollutants were higher than 73%. What concerns the operational parameters, it was found that F/M value, between 0.05 and 0.15 kgCBO5.kg-1MLVSS.d-1, is important to increase efficiency. Increasing the coagulant and flocculant amount in the DAF, the sludge production increases and consequently the phosphorus removal. The sludge purging allows the reduction of biomass in the reactor and increase the F/M ratio.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)
Semi-synthesis of small molecules of aminocarbazoles: tumor growth inhibition and potential impact on p53
The tumor suppressor p53 is inactivated by mutation in approximately 50% of human cancers. Small molecules that bind and stabilize those mutants may represent effective anticancer drugs. Herein, we report the tumor cell growth inhibitory activity of carbazole alkaloids and amino derivatives, as well as their potential activation of p53. Twelve aminocarbazole alkaloids were semi-synthesized from heptaphylline (1), 7-methoxy heptaphylline (2), and 7-methoxymukonal (3), isolated from Clausena harmandiana, using a reductive amination protocol. Naturally-occurring carbazoles 1–3 and their amino derivatives were evaluated for their potential effect on wild-type and mutant p53 activity using a yeast screening assay and on human tumor cell lines. Naturally-occurring carbazoles 1–3 showed the most potent growth inhibitory effects on wild-type p53-expressing cells, being heptaphylline (1) the most promising in all the investigated cell lines. However, compound 1 also showed growth inhibition against non-tumor cells. Conversely, semi-synthetic aminocarbazole 1d showed an interesting growth inhibitory activity in tumor cells expressing both wild-type and mutant p53, exhibiting low growth inhibition on non-tumor cells. The yeast assay showed a potential reactivation of mutant p53 by heptaphylline derivatives, including compound 1d. The results obtained indicate that carbazole alkaloids may represent a promising starting point to search for new mutp53-reactivating agents with promising applications in cancer therapy.The authors thank to national funds provided by FCT—Foundation for Science and Technology and European Regional Development Fund (ERDF) and COMPETE under the Strategic Funding
of CIIMAR UIDB/04423/2020 (Natural Products and Medicinal Chemistry) and LAQV/REQUIMTE
(UID/QUI/50006/2020), the project PTDC/SAU-PUB/28736/2017 (reference POCI-01–0145-FEDER028736), PTDC/DTP-FTO/1981/2014-POCI-01-0145-FEDER-016581). We also thank FCT for the
fellowship SFRH/BD/128673/2017 (J. Loureiro). Ploenthip Puthongking thanks Thailand Research
Fund (DBG6080006), Thailand
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
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
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