A wide array of lignin-related phenolics are oxidized by an evolved bacterial dye-decolourising peroxidase

Lignin is the second most abundant natural polymer next to cellulose and by far the largest renewable source of aromatic compounds on the planet. Dye-decolourising peroxidases (DyPs) are biocatalysts with immense potential in lignocellulose biorefineries to valorize emerging lignin building blocks for environmentally friendly chemicals and materials. This work investigates the catalytic potential of the engineered PpDyP variant 6E10 for the oxidation of 24 syringyl, guaiacyl and hydroxybenzene lignin-phenolic derivatives. Variant 6E10 exhibited up to 100-fold higher oxidation rates at pH 8 for all the tested phenolic substrates compared to the wild-type enzyme and other acidic DyPs described in the literature. The main products of reactions were dimeric isomers with molecular weights of (2 × MWsubstrate - 2 H). Their structure depends on the substitution pattern of the aromatic ring of substrates, i.e., of the coupling possibilities of the primarily formed radicals upon enzymatic oxidation. Among the dimers identified were syringaresinol, divanillin and diapocynin, important sources of structural scaffolds exploitable in medicinal chemistry, food additives and polymers.info:eu-repo/semantics/publishedVersio

Design and anticancer properties of new water-soluble ruthenium–cyclopentadienyl complexes

Ruthenium complexes are emerging as one of the most promising classes of complexes for cancer therapy. However, their limited aqueous solubility may be the major limitation to their potential clinical application. In view and to contribute to the progress of this field, eight new water-soluble Ru(II) organometallic complexes of general formula [RuCp(mTPPMS)n(L)] [CF3SO3], where mTPPMS = diphenylphosphane-benzene-3-sulfonate, for n = 2, L is an imidazole-based ligand (imidazole, 1-benzylimidazole, 1-butylimidazole, (1-(3 aminopropyl)imidazole), and (1-(4-methoxyphenyl)imidazole)), and for n = 1, L is a bidentate heteroaromatic ligand (2-benzoylpyridine, (di(2-pyridyl)ketone), and (1,2-(2-pyridyl)benzo-[b]thiophene)) were synthesized and characterized. The new complexes were fully characterized by NMR, FT-IR, UV–vis., ESI-HRMS, and cyclic voltammetry, which confirmed all the proposed molecular structures. The antiproliferative potential of the new Ru(II) complexes was evaluated on MDAMB231 breast adenocarcinoma, A2780 ovarian carcinoma, and HT29 colorectal adenocarcinoma cell lines, showing micromolar (MDAMB231 and HT29) and submicromolar (A2780) IC50 values. The interaction of complex 6 with human serum albumin (HSA) and fatty-acid-free human serum albumin (HSAfaf) was evaluated by fluorescence spectroscopy techniques, and the results revealed that the ruthenium complex strongly quenches the intrinsic fluorescence of albumin in both cases.info:eu-repo/semantics/publishedVersio

New iron(II) cyclopentadienyl derivative complexes: synthesis and antitumor activity against human leukemia cancer cells

A new family of 'FeII(h5-C5H5)' half sandwich compounds bearing a N-heteroaromatic ligand coordinated to the iron center by a nitrile functional group has been synthesized and fully characterized by NMR and UVeVis spectroscopy. X-ray analysis of single crystal was achieved for complexes 1 and 3, which crystallized in the monoclinic P21/c and monoclinic P21/n space groups, respectively. Studies of interaction of these five new complexes with plasmid pBR322 DNA by atomic force microscopy showed very strong and different types of interaction. Antiproliferative tests were examined on human leukemia cancer cells (HL-60) using the MTT assay, and the IC50 values revealed excellent antiproliferative activity compared to cisplatin

Compostos Organometálicos Contendo Derivados de Tieno[3,2-b]tiofeno com Potencial Comutação das Propriedades de Óptica Não Linear

A comutação das propriedades ópticas não-lineares (NLO) é de grande interesse na área da optoelectrónica e fotónica. O conceito de comutação molecular com base nas propriedades de NLO baseia-se na possibilidade de conseguir uma mudança na resposta óptica não linear entre duas formas ('on' e 'off'), desde que essas duas formas moleculares possuam uma grande diferença na magnitude das respectivas hiperpolarizabilidades. [1] Para conseguir este efeito, podem ser aplicados diversos tipos de estímulos, como o químico, óptico ou electroquímico. [2] Os compostos organometálicos tem um potencial considerável para este fim e os resultados obtidos têm sido motivadores. [3] Neste estudo, apresentam-se compostos organometálicos de ferro(II) e ruténio(II) contendo derivados de tieno[3,2-b]tiofeno que foram estudados com vista à potencial aplicação como comutadores moleculares baseados nas propriedades de óptica não linear de 2ª ordem. Os compostos foram sintetizados e caracterizados pelas técnicas espectroscópicas usuais. O estímulo da alteração de pH foi usado para promover a obtenção das duas formas (‘on’ e ‘off’). A avaliação da possibilidade de comutação molecular foi efectuada por estudos de UV-Vis que mostraram que o intercâmbio reversível entre duas formas moleculares com diferenças visíveis nos seus espectros electrónicos poderá indiciar potenciais aplicações destes compostos como comutadores moleculares com base nas propriedades de óptica não linear de 2ª ordem

Finite element schemes for a class of nonlocal parabolic systems with moving boundaries

The aim of this paper is to study the convergence, properties and error bounds of the discrete solutions of a class of nonlinear systems of reaction–diffusion nonlocal type with moving boundaries, using the finite element method with polynomial approximations of any degree and some classical time integrators. A coordinate transformation which fixes the boundaries is used. Some numerical tests to compare our Matlab code with a moving finite element method are investigated.CAPES – Brazil, Grant BEX 2478-12-9info:eu-repo/semantics/publishedVersio

The Crank–Nicolson–Galerkin Finite Element Method for a Nonlocal Parabolic Equation with Moving Boundaries

The aim of this article is to establish the convergence and error bounds for the fully discrete solutions of a class of nonlinear equations of reaction–diffusion nonlocal type with moving boundaries, using a linearized Crank–Nicolson–Galerkin finite element method with polynomial approximations of any degree. A coordinate transformation which fixes the boundaries is used. Some numerical tests to compare our Matlab code with some existing moving finite element methods are investigated.info:eu-repo/semantics/publishedVersio

A reaction-diffusion model for a class of nonlinear parabolic equations with moving boundaries: Existence, uniqueness, exponential decay and simulation

The aim of this paper is to establish the existence, uniqueness and asymptotic behaviour of a strong regular solution for a class of nonlinear equations of reaction–diffusion nonlocal type with moving boundaries:where is a bounded non-cylindrical domain defined byMoreover, we study the properties of the solution and implement a numerical algorithm based on the Moving Finite Element Method (MFEM) with polynomial approximations of any degree, to solve this class of problems. Some numerical tests are investigated to evaluate the performance of our Matlab code based on the MFEM and illustrate the exponential decay of the solution.info:eu-repo/semantics/publishedVersio