Browsing by Issue Date, starting with "2017-09-19"
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- Synthesis, characterization and biological evaluation of zinc(ii) complexes with phenanthroline derivatives and s-methyl dithiocarbazate schiff basesPublication . Alemu, Yemataw Addis; Cavaco, Isabel; Correia, IsabelThe discovery of novel active compounds with new mechanisms of action, higher efficacy and improved selectivity is a matter of urgency to multi drug resistance and toxicity problems associated with many therapeutic drugs. In the current work S-methyl dithiocarbazate Schiff base: SalSmdt, Mp(Smdt)2, VanSmdt, PySmdt and their Zn(II) complexes: Zn[(SalSmdt)(H2O)]0.5H2O, Zn2[(Mp(Smdt)2)(CH3COO)], Zn[(VanSmdt)(H2O)] and Zn[(PySmdt)(CH3COO)]1.5H2O were synthesized. The Schiff bases were obtained by condensation of S-methyl dithiocarbazate (smdt) with different aromatic aldehydes: salicylaldehyde (sal), o-vanillin (van), pyridoxal (py) and 2,6-diformyl-4-methylphenol (Mp). Additionally, Zn[(phen)2(NO3)2]2H2O, Zn[(aminophen)2(NO3)2]1.5H2O and Zn[(Mephen)2(NO3)2]3.5H2O complexes were developed by reaction of Zn(II) with 1,10- phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (Mephen) and 5-amino-1,10- phenanthroline (aminophen). All compounds were characterized by elemental analysis, FTIR, UV-Vis, NMR, MS and fluorescence spectroscopies. The characterization suggests that the Schiff base ligands coordinate the metal ion through the phenolate–O, the imine-N and the sulfur atom in the thiol form (except in Zn[(PySmdt)(CH3COO)] for which the thione is proposed). The stability of the compounds in buffered aqueous media (5 % DMSO and 95 % PBS, pH 7.4) was evaluated and all compounds are stable at least for three hours. The antioxidant potential was tested using the 2,2-diphenyl-1-picrylhydrazyl assay. All S-methyl dithiocarbazate Schiff bases showed moderate antioxidant activity but the Zn(II) complexes, with the exception of Zn[(PySmdt)(CH3COO)], are inactive. The Zn-phenanthroline complexes were tested for their DNA binding ability by fluorescence spectroscopy. The results indicate that there is interaction between the complexes and calf thymus DNA. Cytotoxicity studies with several tumor cell lines (PC-3, MCF-7 and CACO-2) are ongoing. The results obtained for the Schiff bases are promising since the IC50 values ranged from 4.41 to 28.99 μM. The phenanthroline ligands and their corresponding Zn complexes showed very high cytotoxicity towards A2780 ovarian cancer cells, with the Zn complexes showing slightly higher activity than the ligands.
- Isolation and identification of secondary metabolites from the bryozoan Cryptosula zavjalovensis from Hokkaido, JapanPublication . Gonzaga, Loveille Jun Amarille; Cavaco, Isabel; Fortunato, HelenaThe marine environment is an abundant and diverse source of biologically active compounds, which have great potential in pharmaceutics and medicine. Bryozoans are sessile colonial animals which are common and diverse in shallow waters. Despite their potential for novel biologically active secondary metabolites, there have been very few studies on bryozoans. This work will describe the isolation and identification of secondary metabolites from the marine bryozoan Cryptosula zavjalovensis, which belongs to one of the least studied genera of marine bryozoans. Samples were collected at the Akkeshi Marine Station, Akkeshi, Hokkaido, Japan and were extracted using ethanol. The ethanol extract was evaporated to dryness, dissolved in ethyl acetate and extracted with water to obtain an organic and an aqueous fraction. Preliminary toxicity profiling revealed that the ethyl acetate extract exhibited cytotoxicity toward human MCF7 breast cancer cells. The ethyl acetate extract was separated into three fractions by solid phase extraction using a gradient of methanol and water: E1 80:20 v/v, E2 100:0 v/v, and; E3 methanol and chloroform 50:50 v/v. Toxicity profiling of these extracts revealed E2 and E3 exhibiting toxicity toward human MCF7 breast cancer cells. The secondary metabolites were isolated using liquid chromatography-mass spectrometry and structures were determined by tandem mass spectrometry.
- Study on the different strategies and approaches followed by companies in Portugal and Spain to comply with reach regulationsPublication . Talampas, Shella Ira; Cavaco, Isabel; Sainz, DanielThe implementation of the REACH regulation still experiences significant difficulties in the quality of information provided by companies through their registration dossiers. Given that the success of the REACH process depends primarily on the adequate and reliable information supplied by industries, there is a need to document and manage the knowledge gained and generated since its implementation. This research study documents and examines the issues and concerns experienced as well as the best practices adapted by chemical industries in Spain and Portugal. To accomplish this, the study requested the assistance of chemical industry associations in Spain and Portugal during the period of 2016-2017, before the 2018 deadline for the REACH registration process. Discussion with the Federación Empresarial de la Industria Quimica Española (FEIQUE) in Spain and the Associação Portuguesa das Empresas Químicas (APEQ) in Portugal regarding the necessary data collection for the research study. Online survey questionnaires were then disseminated to member industries of the two associations. The survey questionnaire primarily involved the key processes of REACH – registration, evaluation, authorization and restriction. Out of the chemical industry members of APEQ and FEIQUE, 20 (56%) companies in Portugal participated while in Spain only 6 companies did. Result of the research study is largely based on these respondents. Data from survey questionnaires revealed that major issues and concerns identified by industries were primarily operational issues relating to the implementation of the Substance Information Exchange Forum (SIEF). Among these are communications problems among participants in the implementation of the SIEF, failure to reach an agreement on the sharing of existing data, testing cost and lack of response from suppliers in the use of substance and correction of errors in the SDS as well as difficulties in the use of REACH IT tools. The survey results also revealed that SIEF, where EU-based chemical industries form consortiums and jointly carry out registration and dossier submission, is among the best practices implemented by ECHA and identified by chemical industries. Industries also recognized ECHA’s effort in providing active and good support mechanism in complying with the REACH regulation.
- Assessment of compost for bioremediation of polyaromatic hydrocarbon (pah) and petroleum hydrocarbon soilsPublication . Ferrari, Diana Noemi Guillen; Cavaco, IsabelBioremediation of petroleum and polyaromatic hydrocarbon (PAH) contaminated soils can be a cost effective and efficient treatment approach. The introduction of organic amendments which can provide available nitrogen, and potentially additional microorganisms, can contribute to improve the biodegradation process. However, little work has considered which organic amendments are best in terms of their relative abundance of degraders for specific pollutants. In this work, green waste (GW) composts of different stability were assessed for their bioremediation potential. Twelve compost samples were characterised for parameters including stability (using a modified set up validated in this project), culturable microbial Pseudomonas and Actinomycetes plate counts and degradative gene (alkB, PAH-RHD GP and PAH-RHD GN) abundance. These are important for the degradation of alkanes and PAH respectively. Comparing finished and un-finished green compost from the same site, results showed that the abundance of alkB (encoding alkane monooxygenase) was highest in the less stable compost samples, which corresponds with the higher Pseudomonas counts. Similar results were obtained for PAH-RHD GN (encoding Polycyclic Aromatic Hydrocarbon-Ring Hydroxylating Dioxygenase in Gram negative bacteria), the less stable samples presented higher abundance of degrading genes. For PAH-RHD GP (encoding Polycyclic Aromatic Hydrocarbon-Ring Hydroxylating Dioxygenase in Gram positive bacteria) abundance, it was not possible to see a clear difference between finished and un-finished samples. Given that less stable composts tend to have higher available N this would support the use of these composts for bioremediation of aliphatic petroleum hydrocarbon and Poly aromatic hydrocarbon contaminated soils.