Química

URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11782

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Biochemical responses of Anticarsia gemmatalis (Lepidoptera: Noctuidae) in Soybean cultivars sprayed with the protease Inhibitor Berenil
(Journal of Agricultural and Food Chemistry, 2013-08-02) Paixão, Gilson P.; Lourenção, André L.; Silva, Camila R.; Mendonça, Eduardo G.; Silva, Paulo L.; Oliveira, Joel A.; Zanuncio, José C.; Oliveira, Maria Goreti A.
The damage caused by Anticarsia gemmatalis motivates this study on the adaptive mechanisms of the insect to soybean. The lipoxygenase pathway produces and releases jasmonic acid, involved in the regulation of the plant defense genes, which encodes protease inhibitor (PI) production. Three soybean cultivars IAC-18, IAC-24, and Foscarin-31 were sprayed with water and berenil, a synthetic inhibitor, at 0.60 and 1.0% (w/v) and then infested with A. gemmatalis larvae. The lipoxygenase (LOX) activity increased in the leaves of Foscarin-31, IAC-18, and IAC-24 by 87, 81, and 78%, respectively, after 24 h of A. gemmatalis damage. IAC-18 revealed the lowest increase in PI when compared to the other cultivars. Protease, amidase, and esterase activities in soybean larvae dropped drastically after berenil application. PIs may be included in the control strategies of A. gemmatalis in soybean by lowering the digestive enzyme activity in the larval midgut, thus affecting insect growth and development.
Calix[n]arene-catalyzed three-component povarov reaction: microwave-assisted synthesis of Julolidines and mechanistic insights
(The Journal of Organic Chemistry, 2018-01-16) Abranches, Paula Aline da Silva; Paiva, Walysson Ferreira de; Fátima, Angelo de; Martins, Felipe Terra; Fernandes, Sergio Antonio
A new one-pot cascade reaction-based application of Povarov reactions with a p-sulfonic acid calix[4]arene catalyst for the synthesis of a series of 34 julolidine derivatives with substituents at C8 or C9 in good to excellent yields is reported. These microwave-assisted reactions proceeded efficiently, had short reaction times, were metal-free, were low cost, and used an inexpensive, easily available and nontoxic catalyst. These advantages, along with a simple workup procedure, make this protocol a very efficient and green alternative to the traditional methods for constructing these types of N- heterocyclic skeletons. In addition, this protocol allows the formation of julolidine structures, which requires the construction of four new C−C bonds and two C−N bonds. A mechanism for the Povarov reaction involving a stepwise sequence via ionic intermediates was proposed and validated.
Effect of 1‐Butyl-3-methylimidazolium halide on the relative stability between sodium Dodecyl Sulfate Micelles and sodium Dodecyl Sulfate−Poly(ethylene oxide) Nanoaggregates
(The Journal of Physical Chemistry B, 2015-11-23) Ferreira, Gabriel M. Dias; Ferreira, Guilherme M. Dias; Agudelo, Álvaro J. Patinõ; Silva, Maria C. Hespanhol da; Rezende, Jaqueline de Paula; Pires, Ana Clarissa dos Santos; Silva, Luis Henrique Mendes da
It is well-known that ionic liquids (ILs) alter the properties of aqueous systems containing only surfactants. However, the effect of ILs on polymer–surfactant systems is still unknown. Here, the effect of 1-butyl-3-methylimidazolium bromide (bmimBr) and chloride (bmimCl) on the micellization of sodium dodecyl sulfate (SDS) and its interaction with poly(ethylene oxide) (PEO) was evaluated using conductimetry, fluorimetry, and isothermal titration calorimetry. The ILs decreased the critical micellar concentration (cmc) of the surfactant, stabilizing the SDS micelles. A second critical concentration (c2thc) was verified at high SDS concentrations, due to the micelle size decrease. The stability of PEO/SDS aggregates was also affected by ILs, and the critical aggregation concentration (cac) of SDS increased. Integral aggregation enthalpy changed from −0.72 in water to 2.16 kJ mol–1 in 4.00 mM bmimBr. IL anions did not affect the SDS micellization or the beginning of PEO/SDS aggregation. Nevertheless, when chloride was replaced with bromide, the amount of SDS bound to the polymer increased. At 100.0 mM IL, the PEO-SDS interaction vanished. We suggest that the effect of ILs comes from participating in the structure of the formed aggregates, interacting with the SDS monomers at the core/interface of the micelles, and promoting preferential solvation of the polymer.
Synthetic analogues of the natural compound cryphonectric acid interfere with photosynthetic machinery through two different mechanisms
(Journal of Agricultural and Food Chemistry, 2013-05-17) Teixeira, Róbson Ricardo; Pereira, Wagner Luiz; Tomaz, Deborah Campos; Oliveira, Fabrício Marques de; Giberti, Samuele; Forlani, Giuseppe
A series of isobenzofuran-1(3H)-ones (phthalides), analogues of the naturally occurring phytotoxin cryphonectric acid, were designed, synthesized, and fully characterized by NMR, IR, and MS analyses. Their synthesis was achieved via condensation, aromatization, and acetylation reactions. The measurement of the electron transport chain in spinach chloroplasts showed that several derivatives are capable of interfering with the photosynthetic apparatus. Few of them were found to inhibit the basal rate, but a significant inhibition was brought about only at concentrations exceeding 50 μM. Some other analogues acted as uncouplers or energy transfer inhibitors, with a remarkably higher effectiveness. Isobenzofuranone addition to the culture medium inhibited the growth of the cyanobacterium Synechococcus elongatus, with patterns consistent with the effects measured in vitro upon isolated chloroplasts. The most active derivatives, being able to completely suppress algal growth at 20 μM, may represent structures to be exploited for the design of new active ingredients for weed control.
Tailoring natural abenquines to inhibit the photosynthetic electron transport through interaction with the D1 protein in photosystem II
(Journal of Agricultural and Food Chemistry, 2017-12-01) Nain-Perez, Amalyn; Barbosa, Luiz C. A.; Maltha, Celia R. A.; Giberti, Samuele; Forlani, Giuseppe
Abenquines are natural N-acetylaminobenzoquinones bearing amino acid residues, which act as weak inhibitors of the photosynthetic electron transport chain. Aiming to exploit the abenquine scaffold as a model for the synthesis of new herbicides targeting photosynthesis, 14 new analogues were prepared by replacing the amino acid residue with benzylamines and the acetyl with different acyl groups. The synthesis was accomplished in three steps with a 68−95% overall yield from readily available 2,5-dimethoxyaniline, acyl chlorides, and benzyl amines. Key steps include (i) acylation of the aniline, (ii) oxidation, and (iii) oxidative addition of the benzylamino moiety. The compounds were assayed for their activity as Hill inhibitors, under basal, uncoupled, or phosphorylating conditions, or excluding photosystem I. Four analogues showed high effectiveness (IC 50 = 0.1− 0.4 μM), comparable with the commercial herbicide diuron (IC 50 = 0.3 μM). The data suggest that this class of compounds interfere at the reducing side of photosystem II, having protein D1 as the most probable target. Molecular docking studies with the plastoquinone binding site of Spinacia oleracea further strengthened this proposal.
Theoretical and experimental study of inclusion complexes formed by isoniazid and modified β-Cyclodextrins: 1H NMR structural determination and antibacterial activity evaluation
(The Journal of Physical Chemistry B, 2013-12-09) Teixeira, Milena G.; Assis, João V. de; Soares, Cássia G. P.; Venâncio, Mateus F.; Lopes, Juliana F.; Nascimento Jr, Clebio S.; Anconi, Cleber P. A.; Carvalho, Guilherme S. L.; Lourenço, Cristina S.; Almeida, Mauro V. de; Fernandes, Sergio A.; Almeida, Wagner B. de
Me-β-cyclodextrin (Me-βCD) and HP-β-cyclodextrin (HP-βCD) inclusion complexes with isoniazid (INH) were prepared with the aim of modulating the physicochemical and biopharmaceutical properties of the guest molecule, a well-known antibuberculosis drug. The architectures of the complexes were initially proposed according to NMR data Job plot and ROESY followed by density functional theory (DFT) calculations of (1)H NMR spectra using the PBE1PBE functional and 6-31G(d,p) basis set, including the water solvent effect with the polarizable continuum model (PCM), for various inclusion modes, providing support for the experimental proposal. An analysis of the (1)H NMR chemical shift values for the isoniazid (H6',8' and H5',9') and cyclodextrins (H3,5) C(1)H hydrogens, which are known to be very adequately described by the DFT methodology, revealed them to be extremely useful, promptly confirming the inclusion complex formation. An included mode which describes Me-βCD partially enclosing the hydrazide group of the INH is predicted as the most favorable supramolecular structure that can be used to explain the physicochemical properties of the encapsulated drug. Antibacterial activity was also evaluated, and the results indicated the inclusion complexes are a potential strategy for tuberculosis treatment.