Percorrer por autor "Piedade, M. Fatima M."
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- Eco-friendly synthesis of indo dyes mediated by a bacterial laccasePublication . Sousa, Ana Catarina; Piedade, M. Fatima M.; Martins, Ligia O.; Robalo, Maria PaulaSeveral aminoindamine and indoaniline dyes were obtained in good to excellent yields (64-98%) by oxidative cross-coupling between 1,4-phenylenediamine (1), 4-aminophenol (2) or 2,5-diaminotoluene (3) and several meta- and meta, para-substituted couplers (4a-j) using a green biocatalyst, the bacterial enzyme CotA-laccase from Bacillus subtilis, in water and under mild conditions of pH and temperature. Our results show that the enzymatic route described represents an efficient and sustainable alternative to the chemical synthesis of indo dyes, with a potentially high impact in the cosmetic and hair dye industries.
- Novel "ruthenium cyclopentadienyl" - peptide conjugate complexes against human FGFR(+) breast cancerPublication . Machado, João Franco; Machuqueiro, Miguel; Marques, Fernanda; Robalo, M. Paula; Piedade, M. Fatima M.; Garcia, M. Helena; Correia, João D. G.; Morais, TâniaIn this work we explored the possibility of improving the selectivity of a cytotoxic Ru complex [RuCp(PPh3)(2,2'-bipy)][CF3SO3] (where Cp = eta(5)-cyclopentadienyl) TM34 towards FGFR(+) breast cancer cells. Molecular dynamics (MD) simulations of TM34 in a phosphatidylcholine membrane model pinpointed the cyclopentadienyl group as a favorable derivatization position for the peptide conjugation approach. Three new Ru(II) complexes presenting a functionalized eta(5)-cyclopentadienyl were synthesized, namely [Ru(eta(5)-C5H4COOH)(2,2'-bipy)(PPh3][CF3SO3] (TM281) and its precursors, [Ru(eta(5)-C5H4COOCH2CH3)(eta(2)-2,2'-bipy)(PPh3)][CF3SO3] (3) and [Ru(eta(5)-C5H4COOCH2CH3)(PPh3)(2)Cl] (2). Complex TM281 was prepared by the hydrolysis of the ethyl ester group appended to the eta(5)-cyclopentadienyl ligand of complex 3 with K2CO3 in water/acetonitrile, followed by mild protonation using an ion exchange resin. The newly synthesized complexes were fully characterized by NMR, FTIR and UV-vis spectroscopic techniques. Also, electrochemical studies were carried out by means of cyclic voltammetry in order to evaluate the stability of the compounds. Single crystal X-ray diffraction studies were carried out for compounds 3 and TM281 which crystallized in the monoclinic system, space group P21/n. The unprecedented synthesis and characterization of three half-sandwich ruthenium(II)-cyclopentadienyl peptide conjugates and their preliminary biological evaluation against human FGFR(+) and FGFR(-) breast cancer cells are also reported.
- Synthesis of Substituted 4-Arylamine-1,2-naphthoquinones in One-Pot Reactions Using CotA-Laccase as BiocatalystPublication . Sousa, Ana Catarina; Santos, Iolanda; Piedade, M. Fatima M.; Martins, Lígia O.; Robalo, M. PaulaAn efficient and environmentally benign biocatalytic strategy for the synthesis of substituted 4-arylamino-1,2-naphthoquinones was developed, through a cross-coupling reaction in which the 1,2-naphthoquinone nucleus, formed in the biocatalytic process mediated by CotA-laccase from Bacillus subtilis, is the key synthetic intermediate. Electrochemical data and kinetic parameters were determined revealing a significant higher specificity of CotA-laccase for 4-amino-3-hydroxynaphthalene-1-sulfonic acid (AHNSA). This ability of CotA-laccase to discriminate between oxidisable aromatic amines allows the set-up of one-pot reactions in the presence of the enzyme, between AHNSA and a set of appropriate aromatic amines under mild reaction conditions.