► NaOH-activated carbon produced from flamboyant pods. ► Characteristics of the activated carbon allows that it adsorbs high amount of food dyes. ► Studies of adsorption isotherms and kinetic models ...for dyes.
The adsorption of food dyes, Acid Yellow 6 (AY-6), Acid Yellow 23 (AY-23), and Acid Red 18 (AR-18) onto activated carbon obtained from flamboyant pods (Delonix regia) under optimized conditions (ACop) was performed in this work. According to the pH study, the three dyes best adsorbed in acidic solutions (pH=2). Ten isotherm models, four kinetic models, and the intraparticle diffusion model were applied to fit the experimental data. The Vieth–Sladek isotherm explained the adsorption of the three dyes very well, and the maximum adsorption amounts (Qm) found for AY-6, AY-23, and AR-18 were 673.687, 643.041, and 551.799mgg−1, respectively. The pseudo-second order model gave the best experimental data fit, although its k2 parameter indicated that other mechanisms were involved in the adsorption of AY-6 and AY-23. Similarly, the intraparticle diffusion model indicated that adsorption was governed by several mechanisms. ACop was shown to be a fast and effective adsorbent for the removal of AY-6, AY-23, and AR-18 from aqueous solutions.
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•Design arylcarbamate-N-acylhydrazones derivatives were BuChE selective inhibitors.•The compounds were synthesized using low-cost and simple methodologies.•Compounds 10a-d are potent ...BuChE inhibitors, with IC50 values of 0.07–0.56 µM.•Best inhibitor 10c is non-competitive type of BuChE.•Docking studies confirmed important interactions of 10c with hBuChE active site.
A novel series of arylcarbamate-N-acylhydrazones derivatives have been designed and synthesized as potential anti-cholinesterase agents. In vitro studies revealed that these compounds demonstrated selective for butyrylcholinesterase (BuChE) with potent inhibitory activity. The compounds 10a-d, 12b and 12d were the most potent BuChE inhibitors with IC50 values of 0.07–2.07 µM, highlighting the compound 10c (IC50 = 0.07 µM) which showed inhibitory activity 50 times greater than the reference drug donepezil (IC50 = 3.54 µM). The activity data indicates that the position of the carbamate group in the aromatic ring has a greater influence on the inhibitory activity of the derivatives. The enzyme kinetics studies indicate that the compound 10c has a non-competitive inhibition against BuChE with Ki value of 0.097 mM. Molecular modeling studies corroborated the in vitro inhibitory mode of interaction and show that compound 10c is stabilized into hBuChE by strong hydrogen bond interaction with Tyr128, π-π stacking interaction with Trp82 and CH⋯O interactions with His438, Gly121 and Glu197. Based on these data, compound10cwas identified as low-cost promising candidate for a drug prototype for AD treatment.
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•Pyrimido4,5-dpyridazinone-N-acylhydrazones were synthesized by simple methodologies.•Antifungal activity of compounds was evaluated against P.brasiliensis and Candida spp.•Six ...compounds showed inhibition against Pb18 with MIC of 0.125 to 64 µg.mL−1.•N-acylhydrazone 5a showed potent fungicidal profile with MFC of 0.5 µg mL−1.•Compound 5a showed good synergic effect with amphotericin B and not showed toxicity.
Paracoccidioidomycosis is an endemic mycosis in Latin America for which there is a high mortality rate and limited treatment options. There are no specific drugs to treat the systemic disease. Thus, there is a need for further studies focused on the development of specific drugs. In this work we synthesized new hybrids pyrimido4,5-dpyridazinone-N-acylhydrazone (5a-p) by simple methodologies with good yields. The antifungal activity of compounds was evaluated against P. brasiliensis (Pb18) and Candida spp. Compounds 5a, 5f, 5i, 5 k, 5m and 5n showed significant inhibition against Pb18 with MIC of 0.125 to 64 µg mL−1. Compound 5a is the most promising, showing potent fungicidal profile with MFC of 0.5 µg mL−1, synergic effect with amphotericin B, besides showing no toxicity against HeLa and Vero cells.
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To evaluate (i) the in vitro activity of eugenol (EUG) and three derivatives against Mycobacterium tuberculosis (Mtb), nontuberculous mycobacteria (NTM) and other bacteria, (ii) the EUG and ...antituberculosis drugs combinatory effect and (iii) the EUG and its derivatives cytotoxicity.
Minimum inhibitory concentration of the compounds were determined by resazurin microtiter or broth microdilution assay and the drug interaction between EUG and antituberculosis drugs by resazurin drug combination microtiter. The cytotoxicity was carried out in macrophages, HeLa and VERO cells. Results: EUG and derivatives displayed activity and synergic effect of EUG combined with rifampicin, isoniazid, ethambutol, and pyrazinamide in Mtb including multidrug-resistant isolates, with more selectivity to bacillus than macrophages, HeLa and VERO cells (selective index from 0.65 to 31.4). EUG derivatives (4-allyl-2-methoxyphenyl acetate, 4-allyl-2-methoxyphenyl benzoate, and 4-allyl-2-methoxyphenyl 4-nitrobenzoate) were more active against nontuberculous mycobacteria than EUG. EUG and derivatives exhibited low activity in other Gram-positive and -negative bacteria.
EUG and its derivatives show activity against Mycobacterium spp. and synergic effect of EUG combined with antituberculosis drugs against Mtb.
The presence of strong stereoelectronic interactions involving the substituents in
-2-substituted cyclohexanes may lead to results different from those expected. In this work, we studied the ...conformational behavior of
-2-fluoro- (
),
-2-chloro- (
),
-2-bromo- (
) and
-2-iodocyclohexylamine (
) by dynamic NMR and theoretical calculations. The experimental data pointed to an equilibrium strongly shifted toward the
conformer (equatorial amine group and axial halogen), with populations greater than 90% for
,
and
in both dichloromethane-
and methanol-
. Theoretical calculations (M06-2X/6-311++G(2df,2p)) were in agreement with the experimental, with no influence of the solvent or the halogen on the equilibrium. A principal component analysis of natural bond orbital energies pointed to the σ*
and σ
orbitals and the halogen lone pairs (LP
) as the most significant for the hyperconjugative interactions that influenced the equilibrium. The σ
→ σ*
hyperconjugation and the interactions involving the LP
counterbalance each other, explaining the non-influence of the halogen on the conformational equilibrium. These interactions are responsible for the strong preference for the
conformer in
-2-halocyclohexylamines, being strong enough to restrain the shift in the equilibrium due to other factors such as steric repulsion or solvent effects.
Novel 4-methoxy-naphthalene derivatives were synthesized based on
structures in order to evaluate the antifungal activity against
spp.
Antifungal activity of compounds was evaluated against
.
and ...most promising compounds
and
were tested against eight clinically important fungal species.
Compound
was the more active compound with MIC 8 to 32 μg.ml
for
spp without toxicity monkey kidney and murine macrophagecells. Carbohydrazide
showed good synergistic antifungal activity with amphotericin B against
specie. Titration assay of carbohydrazide
with
HSD enzyme demonstrates the binding ligand-protein. Molecular dynamics simulations show that ligand
let the
HSD protein more stable.
New carbohydrazide
is an attractive lead for drug development to treat paracoccidioidomycoses.
Obtaining a new precursor enamino diketone with five electrophilic centers is reported, along with theoretical and experimental studies of its reactivity against mono- or dinucleophiles. The Fukui ...function showed that the β-carbon is the most electrophilic center, followed by the carbonyl ketone and the carbonyl ester, respectively. The reaction of enamino diketone with aniline and hydrazines allowed for the synthesis of a new enamino diketone and 1,4-disubstituted pyrazoles-5-carboxylates, respectively. The regiochemistry and mechanism of syntheses of 1,4-disubstituted pyrazoles-5-carboxylates were determined from reaction monitoring by ESI-MS, NMR analysis and crystallographic data, and fully agreed with the theoretical results. The versatility and efficiency of the enamino diketone was demonstrated by the reaction with hydrazines furnishing multi-functionalized pyrazoles and pyrazolo3,4-
d
pyridazinone derivatives with high regioselectivity.
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8.
The conformational analysis of 2-halocyclooctanones Rozada, Thiago C.; Gauze, Gisele F.; Rosa, Fernanda A. ...
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy,
02/2015, Volume:
137
Journal Article
Peer reviewed
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•Conformational analysis of 2-halocyclooctanones was fully investigated.•The study was performed through IR and theoretical calculations.•The conformational preferences were very ...sensitive to the solvent polarity.•Stereoelectronic effects, like hyperconjugation and steric effects are also important.
The establishment of the most stable structures of eight membered rings is a challenging task to the field of conformational analysis. In this work, a series of 2-halocyclooctanones were synthesized (including fluorine, chlorine, bromine and iodine derivatives) and submitted to conformational studies using a combination of theoretical calculation and infrared spectroscopy. For each compound, four conformations were identified as the most important ones. These conformations are derived from the chair-boat conformation of cyclooctanone. The pseudo-equatorial (with respect to the halogen) conformer is preferred in vacuum and in low polarity solvents for chlorine, bromine and iodine derivatives. For 2-fluorocyclooctanone, the preferred conformation in vacuum is pseudo-axial. In acetonitrile, the pseudo-axial conformer becomes the most stable for the chlorine derivative. According to NBO calculations, the conformational preference is not dictated by electron delocalization, but by classical electrostatic repulsions.
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Conformational problems often involve very small energy differences, even low as 0.5 kcal mol−1. This accuracy can be achieved by theoretical methods in the gas phase with the appropriate accounting ...of electron correlation. The solution behavior, on the other hand, comprises a much greater challenge. In this study, we conduct and analysis for cis-2-fluoro-, cis-2-chloro-, and cis-2-bromocyclohexanol using low temperature NMR experiments and theoretical calculations (DFT, perturbation theory, and classical molecular dynamics simulations). In the experimental part, the conformers’ populations were measured at 193 K in CD2Cl2, acetone-d 6, and methanol-d 4 solutions; the preferred conformer has the hydroxyl group in the equatorial and the halogen in the axial position (ea), and its population stays at about 60−70%, no matter the solvent or the halogen. Theoretical calculations, on the other hand, put the ae conformer at a lower energy in the gas phase (MP2/6-311++G(3df,2p)). Moreover, the theoretical calculations predict a markedly increase in the conformational energy on going from fluorine to bromine, which is not observed experimentally. The solvation models IEF-PCM and C-PCM were tested with two different approaches for defining the atomic radii used to build the molecular cavity, from which it was found that only with explicit consideration of hydrogens can the conformational preference be properly described. Molecular dynamic simulations in combination with ab initio calculations showed that the ea conformer is slightly favored by hydrogen bonding.
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This study reports the results of ab initio and density functional theory (DFT) electronic structure calculations as well as 3 J HH experimental and calculated coupling constant data obtained in the ...investigation of the conformational equilibrium of 3-halo-derivatives of 1-methylpyrrolidin-2-one. The five-membered ring assumes an envelope conformation owing to the plane of formation of the OC–N–R bond, with C4 forming the “envelope lid”. When the conformation changes, the “lid” alternates between positions above and below the amide plane. The α-carbonyl halogen assumes two positions: a pseudo-axial and a pseudo-equatorial. In the gaseous phase, the calculations indicate that the pseudo-axial conformer is more stable and preferable going down the halogen family. Natural bond orbital analysis showed that electronic delocalization is significant only for the iodo derivative. In the other derivatives, the electrostatic repulsion between oxygen and the halogen determines the conformational equilibrium. When the solvated molecule was taken into account, the pseudo-equatorial conformer population increased with the relative permittivity of the solvent. This variation was strong in the fluoro derivative, and the preference was inverted. In the chlorine derivative, the two populations became closer in methanol and acetonitrile. In the bromine and iodine derivatives, the percentage of pseudo-equatorial conformer increased only slightly owing to the dipole moment of the conformation: the pseudo-equatorial conformation has a greater dipole moment and thus is stable in media with high relative permittivity.
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