Synthesis and luminescence properties of analogues of the green fluorescent protein chromophore

The green fluorescent protein (GFP) is extensively used as a biomarker for fluorescence biological imaging. The chromophore in GFP is only fluorescent when confined into the β–barrel of the protein. Similarly, synthetic analogues of the fluorophore of GFP are usually non-emissive in solution, due to free rotation around the aryl-alkene bond and (Z/E)-isomerization of the double bond. Here, the synthesis and characterization of three analogues of the fluorophore of GFP are reported. The introduction of more electron donating substituents induces a red-shift in the absorption and emission. The fluorophores are more emissive in the solid state than in solution, and a study of their crystal structure reveals that the (Z/E)-isomerization is efficiently blocked in the crystals.publishe

New complexes of manganese (II) and copper (II) derived from the two new furopyran-3, 4-dione ligands: synthesis, spectral characterization, ESR, DFT studies and evaluation of antimicrobial activity

A total of four new metal complex derivatives of two new ligands 2-(hydroxy(phenyl)-6-methyl-2H-furo [3,2-c]pyran-3,4-dione (L1) and 2-(hydroxyl (2-hydroxyphenyl) -6-methyl-2H-furo [3,2-c]pyran-3,4-dione (L2) with the metal ions Mn(II) and Cu(II) have been successfully prepared in alcoholic medium. The complexes obtained are investigated by spectral studies with the use of FT-IR and UV–vis techniques, ESR and magnetic measurements. The IR spectra suggest that the oxygen atoms of the two ligands are engaged in the bond with the central metal. The electronic spectra of the complexes and their magnetic moments provide information about geometries. The molar conductance measurements showed that the complexes are non-electrolytes. Theoretical calculations invoking geometry optimization and molecular orbital description HOMO and LUMO are done using DFT density functional theory. The experimental results and the calculated structural parameters, bond distances and angles, revealed a distorted octahedral geometries around the manganese and copper center through the oxygen of the furan ring for the synthesized complexes ([M(L)2(H2O)2]nH2O; M: metal; L: ligand). The antimicrobial activity of the ligands and their complexes was evaluated in vitro against different bacteria and fungi using agar diffusion method. The ligands and their complexes of manganese (II) and copper (II) exhibited a strong antifungal activity. Copper and manganese complexes have different antibacterial properties against bacteria. The ligand L1 and there complexes were found to be more active against Gram-positive than Gram-negative bacteria.publishe

Synthesis, characterisation, estimation of ground-and excited-state dipole moments using solvatochromic shift and theoretical studies of new iminocoumarin derivatives

The study on the fluorescence and UV–Vis absorption of some iminocoumarins at ambient temperature in several solvents showed a bathochromic shift with the increase of the solvent polarity. The use of the solvathochromic method allowed us to determine the dipole moment in both ground and excited states. The studied molecules exhibit much higher dipole moments in the excited state than in the ground state, which can be due to the redistribution of π-electron densities in the excited state making molecules more polar with higher dipole moments. Furthermore, HOMO–LUMO gap were also estimated theoretically using B3LYP/6–311 + G (d,p) level of theory; the low energy gap indicated the eventual charge transfer interaction occurring in the molecules, and responsible for their light emitting properties.publishe

Salicornia ramosissima: Secondary metabolites and protective effect against acute testicular toxicity

AbstractSalicornia ramosissima J. Woods is a salt tolerant plant currently used in the human diet, whose genus not only displays great potential as a crop plant in deserts and highly saline soils, but also has value in traditional medicine and exhibits promising biological activities. The present study was designed to evaluate the effect of S. ramosissima ethanolic extract on carbon tetrachloride (CCl4)-induced testicular damage in a mouse model and identify secondary metabolites present in the tested extract. The histopathological analysis showed that the treatment with the ethanolic extract prior to CCl4 administration prevented significantly the architectural disorder of seminiferous epithelium and germ cell exfoliation. The phytochemical study allowed the identification of known phenolic and aliphatic compounds [ethyl linolenoate (1), sitostanol (2), octadecyl (3) and eicosanyl (4) (E)-ferulates, ethyl (E)-2-hydroxycinnamate (5), scopoletin (6), a triacylglycerol of tetracosanoic acid (7)], and three new compounds: saliramoester, a long chain triester (8), saliramophenone, a propiophenone derivative (9) and saliramopyrrole a pyrrole-3-carbaldehyde derivative (10). Their chemical structures were elucidated using detailed spectroscopic studies (1D and 2D NMR and MS). These results enhance the value of S. ramosissima as an excellent source of structurally interesting phytochemicals and as protective agent against testicular toxicity

Green synthesis, characterization, structure, biological activity, theoretical calculations and drug-likeness analysis of coumarins

Condensation of salicylaldehydes and 2-hydroxynaphthaldehyde with various β−dicarbonyl derivatives 2a-c, in the presence of KF-Al2O3, leads to the synthesis of a series of coumarins 3-8 and benzo[f]coumarins 10 respectively by a solvent free reaction under microwave irradiation. The catalyst is recovered by a simple filtration and reused in subsequent reactions. The structure of all synthesized compounds has been established by using analytical techniques such as IR, 1H and 13C NMR spectroscopic spectra and elemental analysis. Most of the coumarins exhibited significant antibacterial activity against S. aureus Gram-positive bacteria compared to Cefotaxime as positive control. The compounds 4a and 7a demonstrated moderate antimicrobial activity against compound 8a is extremely sensitive.. In addition, the compounds showed moderate to good antiradical (DPPH) activity. Theoretical calculations let us to confirm the reaction mechanism. Parameters drug-likeness and physicochemical properties including pharmacokinetic analysis of the synthesized compounds was performed using DruliTo program.publishe

Multicomponent and 1,3-dipolar cycloaddition synthesis of triazole- and isoxazole-acridinedione/xanthenedione heterocyclic hybrids: cytotoxic effects on human cancer cells

A new series of diverse 1,2,3-triazole-acridinedione/xanthenedione and 1,2-isoxazole-acridinedione/xanthenedione heterocyclic hybrids have been synthesized via 1,3-dipolar coupling reaction of N/O-substituted-acridinedione-alkyne or O-substituted-xanthenedione-alkyne substrates with various aromatic azides or oximes. In all cases, the cycloaddition is totally regioselective. The chemical structures of the synthesized compounds are determined using 2D NMR and are further confirmed by single-crystal X-ray diffraction analysis. Preliminary in vitro cytotoxic assays on two human breast cancer cell lines (MDA-MB-231, T47-D) and one prostate cancer cell line (PC3) are performed on some selected compounds. The most active O-1,2,3-triazole-xanthenedione hybrid displays the best cytotoxicity effects with IC50 ≤ 20 μM in breast cancer and IC50 = 10 μM in prostate cancer cell lines.publishe

Structural signatures of water-soluble organic aerosols in contrasting environments in South America and Western Europe

This study describes and compares the key structural units present in water-soluble organic carbon (WSOC) fraction of atmospheric aerosols collected in different South American (Colombia – Medellín and Bogotá, Peru – Lima, Argentina – Buenos Aires, and Brazil – Rio de Janeiro, São Paulo, and Porto Velho, during moderate (MBB) and intense (IBB) biomass burning) and Western European (Portugal – Aveiro and Lisbon) locations. Proton nuclear magnetic resonance (1H NMR) spectroscopy was employed to assess the relative distribution of non-exchangeable proton functional groups in aerosol WSOC of diverse origin, for the first time to the authors’ knowledge in South America. The relative contribution of the proton functional groups was in the order H-C > H–C–C= > H-C-O > Ar-H, except in Porto Velho during MBB, Medellín, Bogotá, and Buenos Aires, for which the relative contribution of H-C-O was higher than that of H-C-C=. The 1H NMR source attribution confirmed differences in aging processes or regional sources between the two geographic regions, allowing the differentiation between urban combustion-related aerosol and biological particles. The aerosol WSOC in Aveiro, Lisbon, and Rio de Janeiro during summer are more oxidized than those from the remaining locations, indicating the predominance of secondary organic aerosols. Fresh emissions, namely of smoke particles, becomes important during winter in Aveiro and São Paulo, and in Porto Velho during IBB. The biosphere is an important source altering the chemical composition of aerosol WSOC in South America locations. The source attribution in Medellín, Bogotá, Buenos Aires, and Lima confirmed the mixed contributions of biological material, secondary formation, as well as urban and biomass burning emissions. Overall, the information and knowledge acquired in this study provide important diagnostic tools for future studies aiming at understanding the water-soluble organic aerosol problem, their sources and impact at a wider geographic scale.Fil: Duarte, Regina M.B.O.. Universidade de Aveiro; PortugalFil: Matos, João T.V.. Universidade de Aveiro; PortugalFil: Paula, Andreia S.. Universidade de Aveiro; PortugalFil: Lopes, Sónia P.. Universidade de Aveiro; PortugalFil: Pereira, Guilherme. Universidade de Sao Paulo; BrasilFil: Vasconcellos, Pérola. Universidade de Sao Paulo; BrasilFil: Gioda, Adriana. Universidade Federal do Rio de Janeiro; BrasilFil: Carreira, Renato. Universidade Federal do Rio de Janeiro; BrasilFil: Silva, Artur M.S.. Universidade de Aveiro; PortugalFil: Duarte, Armando C.. Universidade de Aveiro; PortugalFil: Smichowski, Patricia Nora. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rojas, Nestor. Universidad Nacional de Colombia; ColombiaFil: Sanchez Ccoyllo, Odon. No especifíca

A step-by-step synthesis of triazole-benzimidazole-chalcone hybrids: Anticancer activity in human cells+

Novel series of triazole-benzimidazole-chalcone hybrid compounds have been synthesized via click chemistry, between different azide derivatives and substituted benzimidazole terminal alkynes bearing a chalcone moiety. The starting alkynes are prepared via base-catalysed nitrogen alkylation of pre-synthetized benzimidazole-chalcone substrates. All the intermediates as well as the final products are fully characterized by 1D and 2D NMR and mass spectrometry techniques. HMBC correlations permits the identification of a unique 1,4-disubstitued triazole-benzimidazole-chalcone isomer. Evaluation of the anti-proliferative potential in breast and prostate cancer cell lines showed that the presence of chloro substituents at the chalcone ring of the triazole-benzimidazole-chalcone skeleton enhanced the cytotoxic effects. The benzyl group linked to the 1,2,3-triazole moiety provides more antiproliferative potential.publishe

Identification of phenolic constituents of cytisus multiflorus

The phenolic composition of the ethanolic extract obtained from the flowers of the medicinal plant Cytisus multiflorus has been elucidated by high performance liquid chromatography, electrospray mass spectrometry and nuclear magnetic resonance analysis. The extract was mainly composed of flavones, including the common chrysin, orientin, luteolin-5-O-glucoside, luteolin-7-O-glucoside, apigenin and apigenin-7-O-glucoside, which appeared as minor components. The major flavone in the extract was chrysin-7-O-B-D-glucopyranoside, and it also contained moderate amounts of a dihydroxyflavone isomer of chrysin, as well as of 2''-O-pentosyl-6-C-hexosyl-luteolin, 2''-O-pentosyl-8-C-hexosyl-luteolin and 6''- O-(3-hydroxy-3-methylglutaroyl)-2''-O-pentosyl-C-hexosyl-apigenin, which are not commonly found in the Fabaceae family. Other novel phenolic compounds found in the ethanolic extract of C. multiflorus comprised the flavones 2''-O-pentosyl-6-C-hexosyl-apigenin, 2''-O-pentosyl-8-C-hexosyl-apigenin and 6''-O-(3-hydroxy-3-methylglutaroyl)-200-O-pentosyl-C-hexosyl-luteolin. The assessment of the biological activities of the main compounds of this extract are now keen, in order to determine their relevance in the beneficial properties of the plant

A post-synthetic modification strategy for the synthesis of pyrene-fused azaacene covalent organic frameworks

Post-synthetic modification strategy is presented to extend the π-system of covalent organic framework (COF) backbone giving access to boronic ester based pyrene-fused azaacene COFs. Optimized catalyst-free reaction conditions yield COFs post-synthetically modified with up to 33% conversion and corresponding intriguing optical properties. The presented chemistry is expected to find application in post-synthetic tailoring of the optical properties of COFs.S.P.S.F. acknowledges the FCT − Fundação para a Ciência e Tecnologia for the Ph.D. scholarship SFRH/BD/131791/2017. This work received funding from the COFforH2 project (UTA-EXPL/NPN/0055/2019) through the Portuguese Foundation for Science and Technology funds under UT Austin Portugal, Charm project (PTDC/QUI-OUT/2095/2021) through the Portuguese Foundation for Science and Technology funds, The Excellence Clusters ‘Nanosystems Initiative Munich (NIM)’, and from the Free State of Bavaria through the Research Network ‘Solar Technologies go Hybrid’.Peer reviewe