Juliana Alves Pereira Sato

Structural characterization of LASSBio-1289: a new vasoactive N-methyl-N-acylhydrazone derivative

LASSBio-1289 compound has been found to promote intense vasodilation and antihypertensive activity. It is an innovative compound, without structural similarities to the three main classes of calcium antagonists (1,4-dihydropyridines, benzothiazepines and phenylalkylamines) commonly used. A complete knowledge of the structure, including stereochemistry, is essential to lead optimization in drug discovery. For this reason, in this work we determined the crystal structure of this novel vasoactive N-methyl-N-acylhydrazone derivative by means of X-ray powder diffraction data and an ab initio simulating annealing approach, allowing us to observe the relative configuration E of the imine double bond and its conformation as well as its most relevant intermolecular interactions. These findings were also checked by a FTIR analysis and confirmed in solution by NMR. The compound crystallized under a monoclinic crystal system with space group P21/c and unit cell parameters a = 14.5118(3) A, b = 12.1374(2) A, c = 7.5498(1) A, β = 91.113(1)°, V = 1329.53(4) A3, Z = 4, Z′ = 1 and ρcalc = 1.44042(4) g cm−3. Moreover, a crystal morphology prediction, experimentally compared with SEM inferred images, allowed a direct comparison of the microcrystalline habit and quality, allowing a study of the potential solvent effect on the crystal growth.

Photobiosynthesis of stable and functional silver/silver chloride nanoparticles with hydrolytic activity using hyperthermophilic β-glucosidases with industrial potential

The β-glucosidases are important enzymes employed in a large number of processes and industrial applications, including biofuel production from biomass. Therefore, in this study, we reported for the first time the photobiosynthesis of stable and functional silver/silver chloride nanoparticles (Ag/AgCl-NPs) using two hyperthermostable bacterial β-glucosidases with industrial potential. The syntheses were straightforward and rapid processes carried out by mixing β-glucosidase and silver nitrate (in buffer 10mM Tris-HCl, pH 8) under irradiation with light (over a wavelength range of 450-600nm), therefore, compatible with the green chemistry procedure. Synthesized Ag/AgCl-NPs were characterized using a series of physical techniques. Absorption spectroscopy showed a strong absorption band centered at 460nm due to surface plasmon resonance of the Ag-NPs. X-ray diffraction analysis revealed that the Ag/AgCl-NPs were purely crystalline in nature. Under electron microscopy, Ag/AgCl-NPs of variable diameter ranging from 10 to 100nm can be visualized. Furthermore, electron microscopy, zeta potential and Fourier transform infrared spectroscopy results confirmed the presence of β-glucosidases coating and stabilizing the Ag/AgCl-NPs. Finally, the results showed that the enzymatic activities were maintained in the β-glucosidases assisted Ag/AgCl-NPs. The information described here should provide a useful basis for future studies of β-glucosidases assisted Ag/AgCl-NPs, including biotechnological applications.

Systematic studies of the interactions between a model polyphenol compound and microbial β-glucosidases

Lignin is a major obstacle for cost-effective conversion of cellulose into fermentable sugars. Non-productive adsorption onto insoluble lignin fragments and interactions with soluble phenols are important inhibition mechanisms of cellulases, including β-glucosidases. Here, we examined the inhibitory effect of tannic acid (TAN), a model polyphenolic compound, on β-glucosidases from the bacterium Thermotoga petrophila (TpBGL1 and TpBGL3) and archaeon Pyrococcus furiosus (PfBGL1). The results revealed that the inhibition effects on β-glucosidases were TAN concentration-dependent. TpBGL1 and TpBGL3 were more tolerant to the presence of TAN when compared with PfBGL1, while TpBGL1 was less inhibited when compared with TpBGL3. In an attempt to better understand the inhibitory effect, the interaction between TAN and β-glucosidases were analyzed by isothermal titration calorimetry (ITC). Furthermore, the exposed hydrophobic surface areas in β-glucosidases were analyzed using a fluorescent probe and compared with the results of inhibition and ITC. The binding constants determined by ITC for the interactions between TAN and β-glucosidases presented the same order of magnitude. However, the number of binding sites and exposed hydrophobic surface areas varied for the β-glucosidases studied. The binding between TAN and β-glucosidases were driven by enthalpic effects and with an unfavorable negative change in entropy upon binding. Furthermore, the data suggest that there is a high correlation between exposed hydrophobic surface areas and the number of binding sites on the inhibition of microbial β-glucosidases by TAN. These studies can be useful for biotechnological applications.

Rapid Synthesis via Green Route of Plasmonic Protein-Coated Silver/Silver Chloride Nanoparticles with Controlled Contents of Metallic Silver and Application for Dye Remediation

The use of proteins for surface modifications of hybrid silver nanoparticles (NPs) is still poorly explored. In this study, we report a rapid green route synthesis of plasmonic protein-coated silver/silver chloride NPs (Ag/AgCl NPs) with controlled contents of metallic Ag (Ag0) using a modified photo-irradiation method. The contents of Ag0 were easily controlled varying the proportion between Ag+ and Cl− in the syntheses reactions. Interestingly, the Ag0 content in the protein-coated Ag/AgCl NPs increased with increasing of Cl− concentration. The synthesized plasmonic protein-coated Ag/AgCl NPs exhibited significant photocatalytic activity in the reduction of methylene blue dye under light irradiation due to the synergy between the metallic plasmonic effect and the semiconducting AgCl. However, a significant decrease in the content of semiconducting AgCl resulted in an undesirable synergistic effect. In our green route syntheses, all the properties of Ag/AgCl NPs were maintained with the addition of the advantages of the protein layer, which facilitates the dye adsorption and could contribute, along with Ag0, to reduce the electron–hole pairs recombination rate. Thus, with a simple and fast synthesis strategy these organic–inorganic hybrid NPs have the potential for applications for environmental remediation.

CRYSTAL STRUCTURE DETERMINATION OF A N-ACYLHYDRAZONE DERIVATIVE: LASSBIO-1733

The methodology of structure determination from X-ray diffraction data has been employed as a tool able to define the configurational and conformational aspects of the new bioactive compounds, which are directly related to the biological activity. In this work, X-ray powder diffraction (XRPD) was used to carry out the crystal structure determination of LASSBio-1733, which was initially obtained as part of a project of synthesis of novel anti-inflammatory and analgesic leads with a N-acylhydrazone scaffold. The measurements were performed at room temperature on a Stoe STADI-P powder diffractometer in transmission geometry by using a CuKα 1 (λ = 1.54056 A) wavelength. LASSBio-1733 crystallizes in an orthorhombic crystal system, space group P2 1 2 1 2 1 , with unit-cell dimensions a = 25.2049(13) A, b = 10.2952(6) A, c = 5.2333(3) A, α = β = γ = 90 °, V = 1357.99(13) A 3 . The structure was energy-minimised with dispersion-corrected density functional theory (DFT-D). 1 Additionally, other experimental techniques were employed in characterization of this compound.

Structure Determination of LASSBio-1289: A New Antihypertensive Lead-Compound

Hypertension is considered a multi-factorial disease being an important worldwide public-health challenge due to its high frequency and concomitant risks of cardiovascular and other diseases. It has been identified as the leading risk factor for mortality, and is ranked as the third cause of disability-adjusted life-years[1]. The LASSBio-1289 compound was designed from the lead compound LASSBio294 through the use of medicinal chemistry strategy of bioisosteric replacement of aromatic rings[2]. Many factors are involved in the task of describing the relationship between chemical structure and pharmacological activity of a prototype of a new drug. Among these factors the study of atomic-level structure can be included. The aim of this work is to carry out the structural characterization of LASSBio-1289, in solid-state. Since many NAH derivatives, as LASSBio-1289, do not form single crystals for proper structure determination, this task was overcome by using X-ray powder diffraction data and an ab initio simulated annealing procedure. This study can contribute to better understand the full pharmacodynamic profiles and physicochemical properties of this class of compounds. The LASSBio-1289 compound was synthesized following the procedure described in literature[3]. The sample was sofly hand-grinded in an agate mortar in order to get a fine powder suitable for X-ray powder diffraction analysis. The final refined values for the unit-cell parameters after the Rietveld fit were: a = 14.5119(3) Å, b = 12.1375(2) Å, c = 7.5498(1) Å, β = 91.113(1) Å, Z = 4, Z’ = 1 and ρcalc = 1.44039(5) g.m-3. The goodness-of-fit indicator and R-factors were: χ2 = 1.290, RBragg = 1.749%, Rwp = 4.903%, Rexp = 3.802% and Rp = 3.661%. The crystal structure of LASSBio-1289 compound consists of four formula units per unit cell (Z = 4), accommodating one molecule in the asymmetric unit (Z’ = 1). The sample was indexed as monoclinic space group (P21/c).